Expression and localization of growth hormone and its receptors in the chicken ovary during sexual maturation (original) (raw)
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Folia Biologica-krakow, 2013
The purpose of the present study was to examine growth hormone receptor (GHR) gene expression by real-time PCR and demonstrate immunocytochemically the localization of GHR in four chicken oviductal parts, i.e. infundibulum, magnum, isthmus and shell gland. Experiments were carried out on Hy-Line laying hens decapitated 2 h after oviposition. GHR mRNA was expressed in all examined oviductal segments with a significantly lower level in the infundibulum in comparison to other parts of the oviduct. Specific GHR immunoreactivity was also detected in the wall of the oviduct. The intensity of the staining was as follows: infundibulum<isthmus#shell gland#magnum. In all oviductal parts, a positive reaction for GHR was observed in the mucosa whereas a very weak or no reaction was observed in the stroma. Within the mucosa a strong reaction for GHR was observed in the epithelium of the infundibulum and in the tubular gland of the magnum, isthmus and shell gland. Immunoreactivity for GHR was very weak in the mucosal epithelium of the magnum, isthmus and shell gland. In conclusion, the results point to the possibility of an important role of GH in oviduct functions in domestic hens.
Extrapituitary growth hormone in the chicken reproductive system
General and Comparative Endocrinology, 2014
Increasing evidence shows that growth hormone (GH) expression is not limited to the pituitary, as it can be produced in many other tissues. It is known that growth hormone (GH) plays a role in the control of reproductive tract development. Acting as an endocrine, paracrine and/or autocrine regulator, GH influences proliferation, differentiation and function of reproductive tissues. In this review we substantiate the local expression of GH mRNA and GH protein, as well as the GH receptor (GHR) in both male and female reproductive tract, mainly in the chicken. Locally expressed GH was found to be heterogeneous, with a 17 kDa variant being predominant. GH secretagogues, such as GHRH and TRH co-localize with GH expression in the chicken testis and induce GH release. In the ovarian follicular granulosa cells, GH and GHR are co-expressed and stimulate progesterone production, which was neutralized by a specific GH antibody. Both testicular and follicular cells in primary cultures were able to synthesize and release GH to the culture medium. We also characterized GH and GH mRNA expression in the hen's oviduct and showed that it had 99.6% sequence identity with pituitary GH. Data suggest local reproductive GH may have important autocrine/paracrine effects.
Folia Biologica, 2012
HRABIA A., SECHMAN A., RZ¥SA J. 2012. Independent, non-IGF-I mediated, GH action on estradiol secretion by prehierarchical ovarian follicles in chicken. In vitro study. Folia Biologica (Kraków) 60: 213-217. Information concerning the role of growth hormone (GH) in the local regulation of ovarian activity in birds is limited. Therefore, the aim of the present study was to determine whether in the domestic hen GH influences in vitro estradiol secretion by prehierarchical ovarian follicles. Moreover, the interaction between GH and IGF-I on estradiol secretion was examined. Small white (1-4 mm), large white (4-6 mm) and yellowish (6-8 mm) ovarian follicles were isolated at the stage of 2 h after ovulation. In the first experiment (n=8 hens), whole follicles (small white, n=6/dose/ovary; large white, n=1/dose/ovary and yellowish, n=1/dose/ovary) were incubated for 24 h at 38 o C in a medium supplemented with 0 (control), 1, 10 or 100 ng/ml of chicken GH (cGH). In the second experiment (n=6 hens), follicles were incubated in the same way in a medium with 0 (control), 10 ng/ml cGH, 25 ng/ml human IGF-I or cGH+hIGF-I (10 ng/ml+25 ng/ml). Following incubation the estradiol concentration was determined in media (RIA) and protein in the tissues of the follicular wall (Lowry). The secretion of estradiol was expressed per milligram of protein. The experiments revealed that both cGH and hIGF-I stimulated estradiol secretion by examined chicken ovarian follicles.
Cell and Tissue Research, 2011
The aim of this study was to examine the in vivo effect of growth hormone (GH) on cell proliferation and apoptosis and on the gene expression of selected proteins in the chicken oviduct before sexual maturity (first oviposition). Ten-week-old Hy-Line Brown chickens were injected three times a week with 200 μg·kg -1 body weight of recombinant chicken GH (cGH) until 16 weeks of age. Control hens received 0.9 % NaCl with 0.05 % bovine serum albumin as a vehicle. Treatment with cGH increased (P<0.05) oviduct weight at 16 weeks of age, i.e. 1-2 weeks before onset of egg laying. The highest number of proliferating (determined by proliferating cell nuclear antigen [PCNA] immunocytochemistry) and apoptotic (determined by TUNEL assay) cells in the oviduct was found in the mucosal epithelium, and the lowest in the stroma. Administration of cGH did not increase (P>0.05) the number of PCNA-positive cells but it decreased (P<0.01) the number of TUNEL-positive cells, thus increasing the proliferating-to-apoptotic cell ratio in the oviduct. Gene expression (determined by real-time polymerase chain reaction) of apoptosis-related caspase-2 in the magnum and caspase-3 in the magnum and isthmus and their activity (determined by fluorometric assay) in the magnum were attenuated (P<0.05) in cGH-treated hens. The gene expression of the magnum-specific ovalbumin and the shell-gland-specific ovocalyxins 32 and 36 was increased (P<0.05) in cGHtreated chickens. In contrast, the expression of Bcl-2 and of caspases 8 and 9 was not affected by cGH in any of the oviductal segments. The results suggest that GH, via the orchestration of apoptosis and expression of some oviductspecific proteins, participates in the development and activity of the chicken oviduct prior to the onset of egg laying.
General and Comparative Endocrinology, 2004
Growth hormone (GH) gene expression is not confined to pituitary somatotrophs and occurs in many extrapituitary tissues. In this study, we describe the presence of GH moieties in the chicken testis. GH-immunoreactivity (GH-IR), determined by ELISA, was found in the testis of immature and mature chickens, but at concentrations <1% of those in the pituitary gland. The immunoassayable GH concentration in the testis was unchanged between 4 and 66 weeks of age, and approximately 10-fold higher than that at 1-week of age and 25-fold higher than that in 1-day-old chicks and perinatal (embryonic day 18) embryos. This immunoreactivity was associated with several proteins of different molecular size, as in the pituitary gland, when analyzed by SDS-PAGE under reducing conditions. However, while most of the GH-IR in the pituitary ($40 and 15%, respectively) is associated with monomer (26 kDa) or dimer (52 kDa) GH moieties GH-IR in the testis is primarily (30-50%) associated with a 17 kDa moiety. GH bands between 32 and 45 kDa are also relatively more abundant in the testis than in the pituitary. During ontogeny the relative abundance of a 14 kDa GH and 40 kDa GH moieties in the testis significantly declined, whereas the relative abundance of the 17 and 45 kDa moieties increased with advancing age. In adult birds, GH-IR was widespread and intense in the seminiferous tubules. Although the GH-IR was not present in the basal compartment of Sertoli cells, nor in spermatogonia and primary spermatocytes, it was abundantly present in secondary spermatocytes and spermatids in the luminal compartments of the tubules as well as in some surrounding myocytes and interstitial cells. In summary, immunoreactive GH moieties are present in the chicken testis but at concentrations far less than in the pituitary. Age-related changes in the relative abundance of testicular GH variants may be related to local (autocrine/paracrine) actions of testicular GH. The localization of GH in spermatocytes and spermatids suggests hitherto unsuspected roles in gamete development.
Theriogenology, 2014
This study aimed to demonstrate the expression of growth hormone receptor (GH-R) mRNA and protein in goat ovarian follicles in order to investigate the effects of GH on the survival and development of preantral follicles. The ovaries were processed for the isolation of follicles to study GH-R mRNA expression or to localization of GH-R by immunohistochemical analysis. Pieces of ovarian cortex were cultured for 7 days in minimum essential medium þ (MEM þ) in the presence or absence of GH at different concentrations (1, 10, 50, 100, and 200 ng/mL). High expression levels of GH-R mRNA were observed in granulosa/theca cells from large antral follicles. However, preantral follicles do not express mRNA for GH-R. Immunohistochemistry demonstrated that the GH-R protein was expressed in the oocytes/granulosa cells of antral follicles, but any protein expression was observed in preantral follicles. The highest (P < 0.05) rate of normal follicles and intermediate follicles was observed after 7 days in MEM þ plus 10 ng/mL GH (70%). In conclusion, GH-R mRNA and protein are expressed in caprine antral follicles, but not in preantral follicles. Moreover, GH maintains the survival of goat preantral follicles and promotes the development of primordial follicles.
Frontiers in Physiology, 2021
Genetic selection for earlier sexual maturation and extended production cycles in laying hens has significantly improved reproductive efficiency. While limited emphasis has been placed on the underlying physiological changes, we hypothesize that modifications in the control of the hypothalamic-pituitary gonadal (HPG) axis have occurred. Thus, three strains of White leghorn derivatives were followed from hatch to 100 weeks of age (woa), including Lohmann LSL-lite (n = 120) as current commercial hens, heritage Shaver White leghorns (n = 100) as 2000s commercial equivalents, and Smoky Joe hens (n = 68) as 1960s commercial equivalents. Body weight (BW) and egg production were monitored, and blood samples were collected throughout to monitor estradiol (E2) concentrations. Tissue samples were collected at 12, 17, 20, 25, 45, 60, 75, and 100 woa to capture changes in mRNA levels of key genes involved in the HPG axis and monitor ovarian follicular pools. All hens, regardless of strain, age ...
Gonadotropin-inhibitory hormone receptor signaling and its impact on reproduction in chickens
General and Comparative Endocrinology, 2009
In birds, as in other vertebrates, reproduction is controlled by the hypothalamo-pituitary-gonadal axis with each component secreting specific neuropeptides or hormones. Until recently, it was believed this axis is exclusively under the stimulatory control of hypothalamic gonadotropin-releasing hormone I (GnRH-I) which in turn, stimulates luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion from the pituitary gland. However, the discovery of a novel inhibitory hypothalamic peptide able to reduce LH secretion (gonadotropin-inhibitory hormone: GnIH) challenged this dogma. Furthermore, with the characterization of its specific receptor (GnIHR), progress has been made to clarify the physiological relevance of GnIH in birds. This short review discusses the recent advances in GnIHR signaling at the level of the pituitary gland and the gonads. GnIHR is a member of the G-protein coupled receptor (GPCR) family which couples to G ai and, upon activation inhibits adenylyl cyclase (AC) activity, thus reducing intracellular cAMP levels. This implies that GnIH interferes with signaling of any GPCR coupled to G as , including GnRH, LH and FSH receptors. In the chicken pituitary gland, the GnRHR-II/GnIHR ratio changes during sexual maturation in favor of GnRHR-II that appears to result in hypothalamic control of gonadotropin secretion shifting from inhibitory to stimulatory, with corresponding changes in GnRH-induced cAMP levels. Within the gonads, GnIH and its receptor may act in an autocrine/paracrine manner and may interfere with LH and FSH signaling to influence ovarian follicular maturation and recruitment, as well as spermatogenesis.