Magdalena Prusik - Academia.edu (original) (raw)

Papers by Magdalena Prusik

Medycyna Weterynaryjna, 2008

The pineal organs of 14-week-old domestic geese were investigated with light and electron microsc... more The pineal organs of 14-week-old domestic geese were investigated with light and electron microscopy. The pineals consisted of a wide distal part and a narrow middle-proximal one. The glands were attached to the intercommissural region via the choroid plexus. The pineal parenchyma was formed by round or elongated follicles. The follicular wall was composed predominantly by cells immunoreactive with antibodies against hydroxyindolo-O-methyltransferase (HIOMT) or glial fibrillary acid protein (GFAP). They formed two or more layers. HIOMT-positive elements were represented by elongated cells bordering the follicular lumen and oval cells located in the external layer of the follicular wall. These cells were identified in ultrastructural studies as rudimentary-receptor pinealocytes and secretory pinealocytes, respectively. Among rudimentary-receptor pinealocytes two types of cells, designed as A and B, were distinguished due to structural differences. Type A cells extended through the wh...

Anatomical, histological, and ultrastructural studies of the European beaver stomach revealed sev... more Anatomical, histological, and ultrastructural studies of the European beaver stomach revealed several unique morphological features. The prominent attribute of its gross morphology was the cardiogastric gland (CGG), located near the oesophageal entrance. Light microscopy showed that the CGG was formed by invaginations of the mucosa into the submucosa, which contained densely packed proper gastric glands comprised primarily of parietal and chief cells. Mucous neck cells represented,0.1 % of cells in the CGG gastric glands and 22–32 % of cells in the proper gastric glands of the mucosa lining the stomach lumen. These data suggest that chief cells in the CGG develop from undifferentiated cells that migrate through the gastric gland neck rather than from mucous neck cells. Classical chief cell formation (i.e., arising from mucous neck cells) occurred in the mucosa lining the stomach lumen, however. The muscularis around the CGG consisted primarily of skeletal muscle tissue. The cardiac ...

Folia Histochemica et Cytobiologica, 2004

The study was conducted to investigate diurnal changes in pinealocyte ultrastructure, pineal sero... more The study was conducted to investigate diurnal changes in pinealocyte ultrastructure, pineal serotonin content and plasma melatonin concentration in the domestic pig. The immature pigs (n=24) were kept under a cycle of 12 h light : 12 h dark, with a photophase between 0800 and 2000. During the photophase the animals were exposed to direct sunlight. After four weeks the gilts were slaughtered at 0900, 1400, 2100 and 0200. The pineals were removed and divided into two parts - one for quantitative ultrastructural study (by a point count method) and one for serotonin assay. Simultaneously, blood samples were taken for melatonin assay. The relative volume of mitochondria in pinealocyte perikarya was significantly higher at 1400 than at 0200 and 0900 as well as at 2100 than at 0200. The relative volume of Golgi apparatus was higher at 0900 and 1400 than at 0200. The relative volume of dense bodies of the MBB-1 type in pinealocyte perikarya was significantly lower at 1400 and 2100 than at ...

serotonin content and plasma melatonin level in the

Bulletin of The Veterinary Institute in Pulawy, 2010

The aim of this study was to describe plasma melatonin (MLT) profiles in mares from spring equino... more The aim of this study was to describe plasma melatonin (MLT) profiles in mares from spring equinox to summer solstice. Two experiments were performed on 19 warm-blood mares: the first in a veterinary clinic and the second in a stable without electricity and located outside a village. In the first experiment, blood samples were collected at 2-h intervals during 50-h periods in March, April, May, June, and July. In the second experiment blood samples were drawn at 2-h intervals for 26 h in March. Plasma concentrations of MLT were measured by direct RIA. The mean plasma MLT level showed significant (P≤0.05) time-dependent changes in horses sampled in March, April, May, June, and July. In experiment I, the mean level of MLT was significantly elevated (compared to the day-time values at 12.00, 16.00, and 18.00) between 20.00 and 04.00 in March, and between 22.00 and 04.00 in April and May, between 24.00 and 04.00 in June and July. Therefore it could be concluded that the duration of the ...

Neuro endocrinology letters, 2005

OBJECTIVES Cell-permeable and specific inhibitors of melatonin secretion are sill lacking among t... more OBJECTIVES Cell-permeable and specific inhibitors of melatonin secretion are sill lacking among tools of the pineal research. Recently, a large effort has been made in the development of arylalkylamine N-acetyltransferase inhibitors, but in most cases the new drugs were tested exclusively using cell-free assays or non-pineal cells. The aim of the present study was to characterize the effect of N-bromoacetyltryptamine (BAT), the first synthesized cell-permeable inhibitor of arylalkylamine N - acetyltransferase, on melatonin secretion from rat and pig pineal glands. METHODS The studies were performed in the superfusion cultures of rat and pig pineal explants. Melatonin secretion was determined by radioimmunoassay (RIA). RESULTS BAT strongly inhibited the non-stimulated and norepinephrine - stimulated melatonin secretion from the pig and rat pineal explants, with ED50 0.3 - 0.7 microM. The adrenergic stimulation did not modify significantly the inhibitory potency of BAT on the melatoni...

Journal of Elementology, 2007

Summary Retinal dysplasia is an abnormal growth and differentiation of the retina during the†embr... more Summary Retinal dysplasia is an abnormal growth and differentiation of the retina during the†embryonic and early postnatal life. It is characterized by linear folds of the sensory retina and the formation of rosettes composed of variable numbers of neuronal cells. The morphologic classification of retinal dysplasia in dogs includes single or multiple folds, geographic retinal dysplasia, and retinal dysplasia accompanied by retinal detachment and by other systemic abnormalities. There are multiple potential etiologies for retinal dysplasia, including genetic mutations, viruses, toxins and irradiation. Heritable forms of retinal dysplasia have been reported in many breeds of dogs. Mutations that induce retinal dysplasia have not yet been identified. The aim of this paper was to present selected aspects of retinal dysplasia in dogs and cats.

OBJECTIVE The study was performed to analyze structural changes of the turkey pineal during the p... more OBJECTIVE The study was performed to analyze structural changes of the turkey pineal during the post-hatching development. MATERIAL AND METHODS The pineals were collected from male turkeys at the age of 1 day, 2, 8, 22, 56 weeks and subjected to histological investigations including morphometrical analyses. The pinealocytes were identified immunohistochemically using antiserum against hydroxyinolo-O-methyltransferase (HIOMT). RESULTS AND CONCLUSIONS Independently of age, the pineal consisted of a narrow proximal part and a club-shaped top. The narrow part extended into the stalk attached to the diencephalon. The pineal parenchyma was formed by the follicles, surrounded by the connective tissue. The caudal part of the organ contained the pineal lumen, which prolonged into the stalk lumen. Up to the age of two weeks the stalk lumen was open to the third ventricle, later--closed. The proximal part of the stalk showed age-dependent reduction. During the investigated period of life, the ...

ABSTRACT The avian pineal gland releases melatonin in a cyclic manner, with the highest level at ... more ABSTRACT The avian pineal gland releases melatonin in a cyclic manner, with the highest level at night and the lowest level during the daytime. Mechanisms regulating melatonin secretion in birds are very complex, probably due to the phylogenetic position of the avian pineal gland as an intermediate form between the pineals of lower vertebrates and mammals. Avian pinealocytes possess an endogenous oscillator, formed by a self-regulated system of cock genes, that controls the transcription of several enzymes, among them arylalkylamine N-acetyltransferase (AA-NAT), the enzyme limiting melatonin synthesis. These cells are also directly photosensitive due to the presence of photopigments, pinopsin and melanopsin, as well as corresponding signal transduction systems. Light acting via pinopsin induces a cascade of events that leads to the decrease in cGMP and cAMP levels, AA-NAT activity and melatonin secretion. Melanopsin is probably involved in an entrainment of the circadian oscillator to the environmental light conditions. The function of the avian pineal gland is also regulated by light acting indirectly via the retina as well as by the extrapineal oscillator located in the suprachiasmatic nucleus. Both structures influence the pinealocyte activity via a common multisynaptic pathway, which ends in the gland as the sympathetic nerve fibers. Norepinephrine released from these fibers stimulates á2-adrenoreceptors in pinealocyte plasmalemma and inhibits adenylate cyclase activity and melatonin secretion. The significance of direct and indirect routes of light perception as well as intra- and extra-pineal oscillators in the regulation of melatonin secretion may differ between species, but this problem is poorly recognized. Keywords: pineal gland, birds, melatonin, circadian oscillator, photoreception

Animals, Apr 13, 2020

Environmental light regulates a wide range of phenomena in almost all organisms on Earth. Daily a... more Environmental light regulates a wide range of phenomena in almost all organisms on Earth. Daily and seasonal changes in the photoperiod duration are the most important factors controlling the secretion of melatonin (MLT), a pineal hormone that affects many physiological processes in birds. The results of previous studies on the effect of MLT on the productivity and health of poultry have been promising. However, there are very few studies on the daily profiles of plasma MLT concentrations in domestic birds; therefore, we decided to examine plasma MLT levels in 10-week-old domestic turkeys exposed to different light conditions. The results demonstrated that plasma MLT concentration in turkeys kept under a 12 h light: 12 h dark cycle showed a prominent diurnal rhythm. Night-time light exposure caused a rapid decrease in plasma MLT concentrations. The housing of turkeys in continuous dim red light revealed endogenously generated diurnal rhythm of MLT secretion. The rhythm of the plasma MLT level in a reversed cycle of 12 h dark: 12 h light adapted quickly to the new lighting condition.

Medycyna Weterynaryjna, 2018

In birds many life processes runs in diurnal (e.g. locomotor activity, feeding, melatonin secreti... more In birds many life processes runs in diurnal (e.g. locomotor activity, feeding, melatonin secretion) and seasonal rhythms (e.g. reproduction, song, feathering, migration) depending on the environmental light and the activity of their central clock system (CCS). The structure and mechanisms of the activity of the avian CCS are the most complex among vertebrates. CCS consists of three oscillators (in the retina, SCN and pineal gland) possessing their own sensory input system (photopigments) and effective output system (products for direct biological effects). So far, 14 forms of photopigments (

Micron

The avian pineal organ is photosensitive because of the presence of photopigments, of which pinop... more The avian pineal organ is photosensitive because of the presence of photopigments, of which pinopsin seems to be one of the most important. This organ is subject to far-reaching changes during post-hatching development, but evidence regarding pinopsin presence and direct photoreception during this time is lacking. This study was carried out to demonstrate the following: 1) the structures showing immunoreactivity to pinopsin in the turkey pineal organ, 2) the changes of these structures during development, 3) the pinopsin localization in pinealocytes in monolayer cultures, and 4) the role of direct photoreception in the regulation of melatonin secretion in pineal organs in adult turkeys. Pinopsin immunoreactivity was localized in the apical extensions of columnar cells limiting the follicular lumen, in fiber-like structures located between columnar cells in the inner part of follicle wall, in string-shapes or small spherical structures distributed in the outer part of follicle wall and in amorphous material inside the follicle lumen. In young birds, immunoreactivity was also sporadically noted in cell bodies of rudimentary receptor pinealocytes. The distribution of pinopsin showed prominent age-dependent changes, including a subsequent increase in pinopsin-positive structures in the outer part of the follicle wall and a prominent reduction in the number and size of positive apical extensions in 40- and 56-week-old turkeys. These data demonstrate that the role of secretory pinealocytes in pineal photoreception increases with age. In monolayer cultures, all pinealocytes showed strong reactions in club- or bulbous-shaped prolongations. The pineal organs of adult birds were less sensitive to light exposition at night than those of young turkeys, which points to differences in light sensitivity between rudimentary receptor and secretory pinealocytes. However, direct photoreception could play an important role in the regulation of melatonin secretion in adult turkeys.

International Journal of Molecular Sciences

The regulation of melatonin secretion in the avian pineal organ is highly complex and shows promi... more The regulation of melatonin secretion in the avian pineal organ is highly complex and shows prominent interspecies differences. The aim of this study was to determine the roles of direct photoreception and the internal oscillator in the regulation of melatonin secretion in the pineal organ of the domestic turkey. The pineal organs were collected from 12-, 13- and 14-week-old female turkeys reared under a 12 L:12 D cycle with the photophase from 07.00 to 19.00, and were incubated in superfusion culture for 3–6 days. The cultures were subjected to different light conditions including 12 L:12 D cycles with photophases between 07.00 and 19.00, 13.00 and 01.00 or 01.00 and 13.00, a reversed cycle 12 D:12 L, cycles with long (16 L:8 D) and short (8 L:16 D) photophases, and continuous darkness or illumination. The pineal organs were also exposed to light pulses of variable duration during incubation in darkness or to periods of darkness during the photophase. The secretion of melatonin was...

International Journal of Molecular Sciences

The aim of this study was to characterize the embryonic ontogeny of 5-hydroxyindoles and 5-methox... more The aim of this study was to characterize the embryonic ontogeny of 5-hydroxyindoles and 5-methoxyindoles synthesis pathways in the goose pineal organ. The study was performed on embryos aged 14–28 days, which have been incubated under a 12L:12D cycle. The pineal organs were collected for measurements of indole content by HPLC every 6 h on embryonic day (ED) 14, ED 16, ED 18 and ED 22 or every 2 h on ED 24, ED 26 and ED 28. The level of tryptophan showed no significant changes during development and no day-night variations. The content of 5-hydroxytryptophan increased between ED 14 and ED 26. It was significantly higher during scotophase than during photophase starting from ED 14. The serotonin content was low during the early stages of development (ED 14–ED 18) and prominently increased from ED 20. The serotonin levels also showed day-night differences; however, they were less conspicuous than those of 5-hydroxytryptophan. The changes in the level of 5-hydroxyindole acetic acid wer...

Toxins

The contamination of feed with mycotoxins results in reduced growth, feed refusal, immunosuppress... more The contamination of feed with mycotoxins results in reduced growth, feed refusal, immunosuppression, and health problems. Deoxynivalenol (DON) and zearalenone (ZEN) are among the most important mycotoxins. The aim of the study was to examine the effects of low doses of these mycotoxins on the histological structure and ultrastructure of the large intestine in the pig. The study was performed on 36 immature gilts of mixed breed (White Polish Big × Polish White Earhanging), which were divided into four groups administrated per os with ZEN at 40 µg/kg BW, DON at 12 µg/kg BW, a mixture of ZEN (40 µg/kg BW) and DON (12 µg/kg BW) or a placebo. The pigs were killed by intravenous overdose of pentobarbital after one, three, and six weeks of treatment. The cecum, ascending and descending colon samples were prepared for light and electron microscopy. Administration of toxins did not influence the architecture of the mucosa and submucosa in the large intestine. ZEN and ZEN + DON significantly decreased the number of goblet cells in the cecum and descending colon. The mycotoxins changed the number of lymphocytes and plasma cells in the large intestine, which usually increased in number. However, this effect differed between the intestine segments and toxins. Mycotoxins induced some changes in the ultrastructure of the mucosal epithelium. They did not affect the expression of proliferative cell nuclear antigen and the intestinal barrier permeability. The obtained results indicate that mycotoxins especially ZEN may influence the defense mechanisms of the large intestine.

Medycyna Weterynaryjna, 2008

The pineal organs of 14-week-old domestic geese were investigated with light and electron microsc... more The pineal organs of 14-week-old domestic geese were investigated with light and electron microscopy. The pineals consisted of a wide distal part and a narrow middle-proximal one. The glands were attached to the intercommissural region via the choroid plexus. The pineal parenchyma was formed by round or elongated follicles. The follicular wall was composed predominantly by cells immunoreactive with antibodies against hydroxyindolo-O-methyltransferase (HIOMT) or glial fibrillary acid protein (GFAP). They formed two or more layers. HIOMT-positive elements were represented by elongated cells bordering the follicular lumen and oval cells located in the external layer of the follicular wall. These cells were identified in ultrastructural studies as rudimentary-receptor pinealocytes and secretory pinealocytes, respectively. Among rudimentary-receptor pinealocytes two types of cells, designed as A and B, were distinguished due to structural differences. Type A cells extended through the wh...

Anatomical, histological, and ultrastructural studies of the European beaver stomach revealed sev... more Anatomical, histological, and ultrastructural studies of the European beaver stomach revealed several unique morphological features. The prominent attribute of its gross morphology was the cardiogastric gland (CGG), located near the oesophageal entrance. Light microscopy showed that the CGG was formed by invaginations of the mucosa into the submucosa, which contained densely packed proper gastric glands comprised primarily of parietal and chief cells. Mucous neck cells represented,0.1 % of cells in the CGG gastric glands and 22–32 % of cells in the proper gastric glands of the mucosa lining the stomach lumen. These data suggest that chief cells in the CGG develop from undifferentiated cells that migrate through the gastric gland neck rather than from mucous neck cells. Classical chief cell formation (i.e., arising from mucous neck cells) occurred in the mucosa lining the stomach lumen, however. The muscularis around the CGG consisted primarily of skeletal muscle tissue. The cardiac ...

Folia Histochemica et Cytobiologica, 2004

The study was conducted to investigate diurnal changes in pinealocyte ultrastructure, pineal sero... more The study was conducted to investigate diurnal changes in pinealocyte ultrastructure, pineal serotonin content and plasma melatonin concentration in the domestic pig. The immature pigs (n=24) were kept under a cycle of 12 h light : 12 h dark, with a photophase between 0800 and 2000. During the photophase the animals were exposed to direct sunlight. After four weeks the gilts were slaughtered at 0900, 1400, 2100 and 0200. The pineals were removed and divided into two parts - one for quantitative ultrastructural study (by a point count method) and one for serotonin assay. Simultaneously, blood samples were taken for melatonin assay. The relative volume of mitochondria in pinealocyte perikarya was significantly higher at 1400 than at 0200 and 0900 as well as at 2100 than at 0200. The relative volume of Golgi apparatus was higher at 0900 and 1400 than at 0200. The relative volume of dense bodies of the MBB-1 type in pinealocyte perikarya was significantly lower at 1400 and 2100 than at ...

serotonin content and plasma melatonin level in the

Bulletin of The Veterinary Institute in Pulawy, 2010

The aim of this study was to describe plasma melatonin (MLT) profiles in mares from spring equino... more The aim of this study was to describe plasma melatonin (MLT) profiles in mares from spring equinox to summer solstice. Two experiments were performed on 19 warm-blood mares: the first in a veterinary clinic and the second in a stable without electricity and located outside a village. In the first experiment, blood samples were collected at 2-h intervals during 50-h periods in March, April, May, June, and July. In the second experiment blood samples were drawn at 2-h intervals for 26 h in March. Plasma concentrations of MLT were measured by direct RIA. The mean plasma MLT level showed significant (P≤0.05) time-dependent changes in horses sampled in March, April, May, June, and July. In experiment I, the mean level of MLT was significantly elevated (compared to the day-time values at 12.00, 16.00, and 18.00) between 20.00 and 04.00 in March, and between 22.00 and 04.00 in April and May, between 24.00 and 04.00 in June and July. Therefore it could be concluded that the duration of the ...

Neuro endocrinology letters, 2005

OBJECTIVES Cell-permeable and specific inhibitors of melatonin secretion are sill lacking among t... more OBJECTIVES Cell-permeable and specific inhibitors of melatonin secretion are sill lacking among tools of the pineal research. Recently, a large effort has been made in the development of arylalkylamine N-acetyltransferase inhibitors, but in most cases the new drugs were tested exclusively using cell-free assays or non-pineal cells. The aim of the present study was to characterize the effect of N-bromoacetyltryptamine (BAT), the first synthesized cell-permeable inhibitor of arylalkylamine N - acetyltransferase, on melatonin secretion from rat and pig pineal glands. METHODS The studies were performed in the superfusion cultures of rat and pig pineal explants. Melatonin secretion was determined by radioimmunoassay (RIA). RESULTS BAT strongly inhibited the non-stimulated and norepinephrine - stimulated melatonin secretion from the pig and rat pineal explants, with ED50 0.3 - 0.7 microM. The adrenergic stimulation did not modify significantly the inhibitory potency of BAT on the melatoni...

Journal of Elementology, 2007

Summary Retinal dysplasia is an abnormal growth and differentiation of the retina during the†embr... more Summary Retinal dysplasia is an abnormal growth and differentiation of the retina during the†embryonic and early postnatal life. It is characterized by linear folds of the sensory retina and the formation of rosettes composed of variable numbers of neuronal cells. The morphologic classification of retinal dysplasia in dogs includes single or multiple folds, geographic retinal dysplasia, and retinal dysplasia accompanied by retinal detachment and by other systemic abnormalities. There are multiple potential etiologies for retinal dysplasia, including genetic mutations, viruses, toxins and irradiation. Heritable forms of retinal dysplasia have been reported in many breeds of dogs. Mutations that induce retinal dysplasia have not yet been identified. The aim of this paper was to present selected aspects of retinal dysplasia in dogs and cats.

OBJECTIVE The study was performed to analyze structural changes of the turkey pineal during the p... more OBJECTIVE The study was performed to analyze structural changes of the turkey pineal during the post-hatching development. MATERIAL AND METHODS The pineals were collected from male turkeys at the age of 1 day, 2, 8, 22, 56 weeks and subjected to histological investigations including morphometrical analyses. The pinealocytes were identified immunohistochemically using antiserum against hydroxyinolo-O-methyltransferase (HIOMT). RESULTS AND CONCLUSIONS Independently of age, the pineal consisted of a narrow proximal part and a club-shaped top. The narrow part extended into the stalk attached to the diencephalon. The pineal parenchyma was formed by the follicles, surrounded by the connective tissue. The caudal part of the organ contained the pineal lumen, which prolonged into the stalk lumen. Up to the age of two weeks the stalk lumen was open to the third ventricle, later--closed. The proximal part of the stalk showed age-dependent reduction. During the investigated period of life, the ...

ABSTRACT The avian pineal gland releases melatonin in a cyclic manner, with the highest level at ... more ABSTRACT The avian pineal gland releases melatonin in a cyclic manner, with the highest level at night and the lowest level during the daytime. Mechanisms regulating melatonin secretion in birds are very complex, probably due to the phylogenetic position of the avian pineal gland as an intermediate form between the pineals of lower vertebrates and mammals. Avian pinealocytes possess an endogenous oscillator, formed by a self-regulated system of cock genes, that controls the transcription of several enzymes, among them arylalkylamine N-acetyltransferase (AA-NAT), the enzyme limiting melatonin synthesis. These cells are also directly photosensitive due to the presence of photopigments, pinopsin and melanopsin, as well as corresponding signal transduction systems. Light acting via pinopsin induces a cascade of events that leads to the decrease in cGMP and cAMP levels, AA-NAT activity and melatonin secretion. Melanopsin is probably involved in an entrainment of the circadian oscillator to the environmental light conditions. The function of the avian pineal gland is also regulated by light acting indirectly via the retina as well as by the extrapineal oscillator located in the suprachiasmatic nucleus. Both structures influence the pinealocyte activity via a common multisynaptic pathway, which ends in the gland as the sympathetic nerve fibers. Norepinephrine released from these fibers stimulates á2-adrenoreceptors in pinealocyte plasmalemma and inhibits adenylate cyclase activity and melatonin secretion. The significance of direct and indirect routes of light perception as well as intra- and extra-pineal oscillators in the regulation of melatonin secretion may differ between species, but this problem is poorly recognized. Keywords: pineal gland, birds, melatonin, circadian oscillator, photoreception

Animals, Apr 13, 2020

Environmental light regulates a wide range of phenomena in almost all organisms on Earth. Daily a... more Environmental light regulates a wide range of phenomena in almost all organisms on Earth. Daily and seasonal changes in the photoperiod duration are the most important factors controlling the secretion of melatonin (MLT), a pineal hormone that affects many physiological processes in birds. The results of previous studies on the effect of MLT on the productivity and health of poultry have been promising. However, there are very few studies on the daily profiles of plasma MLT concentrations in domestic birds; therefore, we decided to examine plasma MLT levels in 10-week-old domestic turkeys exposed to different light conditions. The results demonstrated that plasma MLT concentration in turkeys kept under a 12 h light: 12 h dark cycle showed a prominent diurnal rhythm. Night-time light exposure caused a rapid decrease in plasma MLT concentrations. The housing of turkeys in continuous dim red light revealed endogenously generated diurnal rhythm of MLT secretion. The rhythm of the plasma MLT level in a reversed cycle of 12 h dark: 12 h light adapted quickly to the new lighting condition.

Medycyna Weterynaryjna, 2018

In birds many life processes runs in diurnal (e.g. locomotor activity, feeding, melatonin secreti... more In birds many life processes runs in diurnal (e.g. locomotor activity, feeding, melatonin secretion) and seasonal rhythms (e.g. reproduction, song, feathering, migration) depending on the environmental light and the activity of their central clock system (CCS). The structure and mechanisms of the activity of the avian CCS are the most complex among vertebrates. CCS consists of three oscillators (in the retina, SCN and pineal gland) possessing their own sensory input system (photopigments) and effective output system (products for direct biological effects). So far, 14 forms of photopigments (

Micron

The avian pineal organ is photosensitive because of the presence of photopigments, of which pinop... more The avian pineal organ is photosensitive because of the presence of photopigments, of which pinopsin seems to be one of the most important. This organ is subject to far-reaching changes during post-hatching development, but evidence regarding pinopsin presence and direct photoreception during this time is lacking. This study was carried out to demonstrate the following: 1) the structures showing immunoreactivity to pinopsin in the turkey pineal organ, 2) the changes of these structures during development, 3) the pinopsin localization in pinealocytes in monolayer cultures, and 4) the role of direct photoreception in the regulation of melatonin secretion in pineal organs in adult turkeys. Pinopsin immunoreactivity was localized in the apical extensions of columnar cells limiting the follicular lumen, in fiber-like structures located between columnar cells in the inner part of follicle wall, in string-shapes or small spherical structures distributed in the outer part of follicle wall and in amorphous material inside the follicle lumen. In young birds, immunoreactivity was also sporadically noted in cell bodies of rudimentary receptor pinealocytes. The distribution of pinopsin showed prominent age-dependent changes, including a subsequent increase in pinopsin-positive structures in the outer part of the follicle wall and a prominent reduction in the number and size of positive apical extensions in 40- and 56-week-old turkeys. These data demonstrate that the role of secretory pinealocytes in pineal photoreception increases with age. In monolayer cultures, all pinealocytes showed strong reactions in club- or bulbous-shaped prolongations. The pineal organs of adult birds were less sensitive to light exposition at night than those of young turkeys, which points to differences in light sensitivity between rudimentary receptor and secretory pinealocytes. However, direct photoreception could play an important role in the regulation of melatonin secretion in adult turkeys.

International Journal of Molecular Sciences

The regulation of melatonin secretion in the avian pineal organ is highly complex and shows promi... more The regulation of melatonin secretion in the avian pineal organ is highly complex and shows prominent interspecies differences. The aim of this study was to determine the roles of direct photoreception and the internal oscillator in the regulation of melatonin secretion in the pineal organ of the domestic turkey. The pineal organs were collected from 12-, 13- and 14-week-old female turkeys reared under a 12 L:12 D cycle with the photophase from 07.00 to 19.00, and were incubated in superfusion culture for 3–6 days. The cultures were subjected to different light conditions including 12 L:12 D cycles with photophases between 07.00 and 19.00, 13.00 and 01.00 or 01.00 and 13.00, a reversed cycle 12 D:12 L, cycles with long (16 L:8 D) and short (8 L:16 D) photophases, and continuous darkness or illumination. The pineal organs were also exposed to light pulses of variable duration during incubation in darkness or to periods of darkness during the photophase. The secretion of melatonin was...

International Journal of Molecular Sciences

The aim of this study was to characterize the embryonic ontogeny of 5-hydroxyindoles and 5-methox... more The aim of this study was to characterize the embryonic ontogeny of 5-hydroxyindoles and 5-methoxyindoles synthesis pathways in the goose pineal organ. The study was performed on embryos aged 14–28 days, which have been incubated under a 12L:12D cycle. The pineal organs were collected for measurements of indole content by HPLC every 6 h on embryonic day (ED) 14, ED 16, ED 18 and ED 22 or every 2 h on ED 24, ED 26 and ED 28. The level of tryptophan showed no significant changes during development and no day-night variations. The content of 5-hydroxytryptophan increased between ED 14 and ED 26. It was significantly higher during scotophase than during photophase starting from ED 14. The serotonin content was low during the early stages of development (ED 14–ED 18) and prominently increased from ED 20. The serotonin levels also showed day-night differences; however, they were less conspicuous than those of 5-hydroxytryptophan. The changes in the level of 5-hydroxyindole acetic acid wer...

Toxins

The contamination of feed with mycotoxins results in reduced growth, feed refusal, immunosuppress... more The contamination of feed with mycotoxins results in reduced growth, feed refusal, immunosuppression, and health problems. Deoxynivalenol (DON) and zearalenone (ZEN) are among the most important mycotoxins. The aim of the study was to examine the effects of low doses of these mycotoxins on the histological structure and ultrastructure of the large intestine in the pig. The study was performed on 36 immature gilts of mixed breed (White Polish Big × Polish White Earhanging), which were divided into four groups administrated per os with ZEN at 40 µg/kg BW, DON at 12 µg/kg BW, a mixture of ZEN (40 µg/kg BW) and DON (12 µg/kg BW) or a placebo. The pigs were killed by intravenous overdose of pentobarbital after one, three, and six weeks of treatment. The cecum, ascending and descending colon samples were prepared for light and electron microscopy. Administration of toxins did not influence the architecture of the mucosa and submucosa in the large intestine. ZEN and ZEN + DON significantly decreased the number of goblet cells in the cecum and descending colon. The mycotoxins changed the number of lymphocytes and plasma cells in the large intestine, which usually increased in number. However, this effect differed between the intestine segments and toxins. Mycotoxins induced some changes in the ultrastructure of the mucosal epithelium. They did not affect the expression of proliferative cell nuclear antigen and the intestinal barrier permeability. The obtained results indicate that mycotoxins especially ZEN may influence the defense mechanisms of the large intestine.