Pineal gland size and serum melatonin levels in male rats are not correlated (original) (raw)
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The ontogeny of pineal and serum melatonin in male rats at mid-light and mid-dark
Journal of Neural Transmission, 1988
The levels of pineal and serum melatonin at mid-light and mid-dark of male rats under a photoperiod of 12 h light: 12 h darkness with age ranging from day 1 to day 42 postpartum were determined. At mide-dark, pineal melatonin levels were found to increase with age; when the body weight was considered, an early developmental rise (1-to-9-day old), an active period (11to 17-day old), and a period of lower levels (after 21-day-old) were noted. Serum melatonin levels at mid-dark showed similar changes to the latter. At mid-light, this pattern of change was also present in pineal melatonin contents relative to body weight but was absent in serum melatonin levels. Our study indicated that weaning was not responsible for the pre-pubertal decline in pineal melatonin secretion. It was suggested that these changes in the secretory pattern of pineal melatonin may play a role in the development of the reproductive system in rats.
Pituitary-adrenal and thyroid effects on melatonin content of the rat pineal gland
Psychoneuroendocrinology, 1989
Based on clinical findings of diminished nocturnal serum melatonin levels in affective illness, we hypothesized that alterations in the pituitary-adrenal or thyroid axes of the rat might alter the nocturnal rise of melatonin content of the pineal gland in that species. Two experiments were conducted to investigate these issues. In the first, rats were injected for nine days with adrenocorticotropic hormone (ACTH) or corticosterone, timed to accentuate and prolong the normal circadian corticosterone rise. Although both these treatments produced significant elevations of serum corticosterone, there was no difference in pineal melatonin content during the day or night from that measured in control rats. In the second experiment, hypothyroidism was induced in rats by thyroid-parathyroidectomy, and hyperthyroidism was produced by injection of triiodotlfyronine (T3) for nine days. Despite clear evidence of metabolic and endocrine effects of these thyroid manipulations, pineal melatonin content was not altered during the day or night. The nocturnal increase of melatonin may have been phaseadvanced in the hypothyroid group, although the experiment was not designed to detect such a shift. There thus is no evidence from this study in the rat to suggest that diminished nocturnal melatonin production in affective illness might be due to associated alterations in the pituitary-adrenal or thyroid systems.
Journal of Pineal Research, 1990
Melatonin in the systemic circulation of rats fluctuates with age, and the causes for such changes were investigated. Male rats (aged 7 days, 16 days, 18 days, 20 days, 30 days, 48 days, 60 days, and >17 months) were adapted under a lighting regime of 12L:12D for at least 7 days. Pineals and blood samples from the trunk or confluens sinuum were collected in the dark period. Melatonin in tissues was extracted, identified, and determined by gas chromatography-mass spectrometry (GC-MS) and/or radioimmunoassay. Tissue melatonin levels obtained by radioimmunoassay correlated closely with those quantified by GC-MS. Thus, the melatonin radioimmunoassay used is a reliable assay method for melatonin in the plasma and pineal of the rat.
The Journal of experimental zoology, 1984
Pineal concentrations of N-acetylserotonin and melatonin and serum levels of melatonin were studied in 3-wk-old (prepubertal), 8-wk-old (adult), and 17-mo-old (senile) male rats. They were adapted to a photoperiod of 12 h light/12 h darkness for a minimum of 1 wk and killed at mid-light and mid-dark. Melatonin and N-acetylserotonin were determined by radioimmunoassay. The concentrations of pineal N-acetylserotonin and melatonin were high in the dark period and low in the light period. Statistical analysis indicated that pineal N-acetylserotonin and melatonin levels per 100 gm body weight declined with age. Similarly, serum melatonin demonstrated diurnal changes in all the age groups studied. In addition, there was a significant reduction in the levels of serum melatonin with age. The parallel patterns of decrease in pineal and serum melatonin levels with age suggest a decline in pineal secretion of melatonin in the older animals.
A brief review about melatonin, a pineal hormone
2018
Melatonin is a ubiquitous molecule in nature, being locally synthesized in several cells and tissues, besides being a hormone that is centrally produced in the pineal gland of vertebrates, particularly in mammals. Its pineal synthesis is timed by the suprachiasmatic nucleus, that is synchronized to the light-dark cycle via the retinohypothalamic tract, placing melatonin synthesis at night, provided its dark. This unique trait turns melatonin into an internal synchronizer that adequately times the organism's physiology to the daily and seasonal demands. Besides being amphiphilic, melatonin presents specific mechanisms and ways of action devoted to its role as a time-giving agent, being widely spread in the organism. The present review aims to focus on melatonin as a pineal hormone with specific mechanisms and ways of action, besides presenting the clinical syndromes related to its synthesis and/or function disruptions. Arch Endocrinol Metab. 2018;62(4):472-9
Length, Breadth and Thickness of the Pineal Gland
Bangladesh Journal of Anatomy, 2013
Context: The pineal gland is capable of influencing or modifying the activity of the pituitary gland, islets of Langerhans, the parathyroid gland, adrenal gland and the gonads. The pineal gland through its hormone, melatonin influences many functions of the human, like circadian rhythm, mood, psychiatric disorder, sexual maturation, reproduction and aging. Melatonin, a potent antioxidant provides protection against damaging free radicals of oxygen. Various clinical problems occur due to abnormal melatonin secretion by the pineal gland. For the perfect and complete evaluation of various clinical conditions of the pineal gland, detailed morphological knowledge is essential. Study Design: Cross sectional analytical type of study. Place and period of study: Department of Anatomy, Dhaka Medical College, Dhaka from July 2009 to June 2010. Materials: 60 postmortem human pineal glands were collected from unclaimed dead bodies that were under examination in the morgue of the Department of Fo...
Melatonin — More than Just a Pineal Hormone
Biomedical Journal of Scientific & Technical Research, 2017
As summarized elsewhere [6,7], melatonin formation has been demonstrated in various regions of the central nervous system, especially cerebellum and retina, in the membranous cochlea, lens, glomus caroticum, gastrointestinal tract (GIT), cholangiocytes of liver, bone marrow, various leukocytes, thymus, spleen, kidney, heart, ovary, placenta, skin, airway epithelia, and, in rodents, the Harderian gland. The amounts formed there are highly different and, with regard to the brain, divergent [9]. In many cases studied, with the exception of the retina, circadian rhythmicity of extrapineal