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NGF, BDNF, NT-3 and their specific receptors TrkA, TrkB and TrkC are known to be involved in the development and maintenance of vertebrates’ nervous system. However, these molecules play a role also in non-neuronal tissue, such as in the reproductive system. In this study we investigated the presence and localization of neurotrophins and Trk receptors to unravel their potential role in the developing and adult ovary of Japanese quail, a model species well suited for reproduction studies. Western blotting analysis on ovaries of three month old quails in the period of egg laying showed the presence of pro and mature forms of neurotrophins and splice variants of Trk receptors. Immunohistochemical investigation reported that in embryonic ovaries from the 9th day of incubation to the hatching NGF and NT-3 were observed in the cortical and medullar areas respectively, whereas Trk receptors were observed in both areas. In adult ovary, all NTs were detected in glandular stromal cells, NGF and NT-3 also in the nervous component. Regarding follicle components, NGF and BDNF were observed in oocytes and follicular cells. All TrK receptors were present in nervous components and only TrkA in glandular stromal cells. In follicles, TrkA was present in oocyte cytoplasm and TrkB in theca cells. The results suggest an involvement of the neurotrophin system in the quail ovary physiology, promoting the oocyte development and follicular organization in the embryo, as well as oocyte and follicular maturation in adults. [ABSTRACT FROM AUTHOR]

Neurotrophins (NGF, BDNF and NT-3) and their specific receptors (TrkA, TrkB and TrkC) were studied in the oviduct of egg laying quails. Neurotrophins (NTs) are mainly involved in the development and maintenance of neuronal populations in the central and peripheral nervous system, but also in reproductive system. In this survey, we first studied the morphological organization of the quail oviduct, distinguished in infundibulum, magnum, isthmus, uterus and vagina, and then we analyzed the expression and localization of NTs and Trks receptors in the whole tracts. By western blotting we detected that the investigated NTs and Trks receptors are expressed in all oviductal tracts. By immunohistochemistry we were able to define the distribution of NTs and Trks. Specifically, NGF, BDNF and NT3 were localized in lining and ductal epithelial cells, and NGF was also detected in secretory cells of tubular glands and in nervous fibers of vessel wall. TrkA and TrkB were present in the lining and ductal epithelium; TrkA and TrkC were present in nervous fibers of vessel wall in all oviductal tracts. Furthermore, we also observed NGF and BDNF co-localized with TrkA and TrkB in cells of the lining and ductal epithelium, suggesting an autocrine mechanism of action. [ABSTRACT FROM AUTHOR]

Neurotrophins (NGF, BDNF and NT-3) and their specific receptors (TrkA, TrkB and TrkC) were studied in the oviduct of egg laying quails. Neurotrophins (NTs) are mainly involved in the development and maintenance of neuronal populations in the central and peripheral nervous system, but also in reproductive system. In this survey, we first studied the morphological organization of the quail oviduct, distinguished in infundibulum, magnum, isthmus, uterus and vagina, and then we analyzed the expression and localization of NTs and Trks receptors in the whole tracts. By western blotting we detected that the investigated NTs and Trks receptors are expressed in all oviductal tracts. By immunohistochemistry we were able to define the distribution of NTs and Trks. Specifically, NGF, BDNF and NT3 were localized in lining and ductal epithelial cells, and NGF was also detected in secretory cells of tubular glands and in nervous fibers of vessel wall. TrkA and TrkB were present in the lining and ductal epithelium; TrkA and TrkC were present in nervous fibers of vessel wall in all oviductal tracts. Furthermore, we also observed NGF and BDNF co-localized with TrkA and TrkB in cells of the lining and ductal epithelium, suggesting an autocrine mechanism of action. [ABSTRACT FROM AUTHOR]

Neurotrophin-4 (NT-4) is a member of the well-known family of neurotrophins that regulate the development of neuronal networks by participating in neuronal survival and differentiation, the growth of neuronal processes, synaptic development and plasticity, as well as myelination. NT-4 interacts with two distinct receptors: TrkB, high affinity receptor and p75 low-affinity neurotrophin receptor (p75 NTR ). In the present survey, we identified the gene encoding NT-4 in the teleost Nothobranchius furzeri , a model species for aging research. The identified gene shows a similarity of about 72% with medaka, the closest related species. The neuroanatomical localization of NT-4 mRNA is obtained by using an LNA probe. NT-4 mRNA expression is observed in neurons and glial cells of the forebrain and hindbrain, with very low signal found in the midbrain. This survey confirms that NT-4 is expressed in the brain of N. furzeri during adulthood, suggesting that it could also be implicated in the maintenance and regulation of neuronal functions. [ABSTRACT FROM AUTHOR]

Abstract: Nerve growth factor (NGF) acts on central nervous system neurons, regulating naturally occurring cell death, synaptic connectivity, fiber guidance and dendritic morphology. The dynamically regulated production of NGF beginning in development, extends throughout adult life and aging, exerting numerous roles through a surprising variety of neurons and glial cells. This study analyzes the localization of NGF in the brain of the teleost fish Nothobranchius furzeri, an emerging model for aging research due to its short lifespan. Immunochemical and immunohistochemical experiments were performed by employing an antibody mapping at the N-terminus of the mature chain human origin NGF. Western blot analysis revealed an intense and well defined band of 20kDa, which corresponds to proNGF of N. furzeri. Immunohistochemistry revealed NGF immunoreactivity (IR) diffused throughout all regions of telencephalon, diencephalon, mesencephalon and rhomboencephalon. It was detected in neurons and in glial cells, the latter mostly lining the mesencephalic and rhomboencephalic ventricles. Particularly in neurons, NGF IR was localized in perikarya and, to a less extent, in fibers. The widespread distribution of proNGF suggests that it might modulate numerous physiological functions in the adult brain of N. furzeri. The present survey constitutes a baseline study to enhance the understanding of the mechanisms underlying the role of NGF during aging processes. [Copyright &y& Elsevier]

Glial cell line-derived neurotrophic factor (GDNF) acts through RET receptor tyrosine kinase and its co-receptor GFRalpha1. In an effort to better understand the possible biological contribution of the GDNF and GFRalpha1/RET complex in pancreatic development, in this study we report the cellular localization of these proteins in the pancreas of domestic cat embryos and fetuses by immunocytochemical methods. In early embryos, GDNF, GFRalpha and RET immunoreactivity (IR) was localized in closely intermingled cells. GDNF and RET immunoreactive cells displayed chromogranin (an endocrine marker) and PGP 9.5 (a neuronal marker) IR, respectively. GFRalpha IR was present in both a few GDNF/chromogranin and RET/PGP 9.5 immunoreactive cells. In elderly fetuses, GDNF and GFRalpha IR were co-localized in glucagon cells and RET IR was detected in few neurons and never co-localized with GFRalpha or GDNF IR. In early embryos, the presence of GDNF IR in chromogranin immunoreactive cells and GFRalpha1/RET complex IR in PGP9.5 immunoreactive cells seems to suggest a paracrine action of GDNF contained in endocrine cell precursors on neuronal cell precursors expressing its receptor complex. The presence in different cell populations of RET and its co-receptor GFRalpha1 IR could be due to independent signaling of GRFalpha1. Thus, the co-presence of GDNF and GFRalpha1 in chromogranin and glucagon cells could lead to the hypothesis that GDNF can act in an autocrinal manner. In fetuses, RET IR was detected only in intrapancreatic ganglia. Because of the lack of GFRalpha1 IR in pancreatic innervation, RET receptor could be activated by other GFR alphas and ligands of GDNF family. In conclusion, these findings suggest that in differently aged embryos and fetuses the GDNF signal is differently mediated by RET and GFRalpha1. [ABSTRACT FROM AUTHOR]

Glial-derived neurotrophic factor (GDNF), neurturin (NRTN), persephin (PSPN), and artemin (ARTN) are a group of proteins belonging to the GDNF family ligands (GFLs). GDNF, NRTN, and ARTN support the survival of central, peripheral, and autonomic neuron populations, while PSPN supports the survival of only several central neuron populations. A common receptor, RET, modulates the action of this family and a co-receptor, GFRα, determines RET ligand specificity. GDNF and NRTN appear to be essential for enteric nervous system (ENS) development in mammals, zebrafish, and other teleostean species. GFLs are also essential for the maintenance and plasticity of adult mammalian ENS. In this study, the distribution pattern of GFLs in the intestine of five adult fish (bass, gilt-head, scorpionfish, trout, and zebrafish) was evaluated by immunochemical and immunocytochemical analysis. The results demonstrated the presence of GDNF, NRTN, and ARTN in the gut of all species studied. They appeared to be spread in the ENS and/or endocrine cells of the intestine. These findings suggest that the presence of GFLs in fish gut is not only limited to developmental period, but could be also involved in the enteric physiology of adult species. [ABSTRACT FROM AUTHOR]

Brain-derived neurotrophic factor (BDNF) is a growth factor that belongs to the group of neurotrophins. Its amino acid sequences are well conserved during vertebrate phylogenesis. Pancreatic tissue has recently been reported to be one of the physiological sources of BDNF in humans and mice. In this study we investigated the presence and localization of BDNF immunoreactivity (IR) in the pancreas of three species of higher vertebrates: mouse, duck and lizard. BDNF IR was present in the islets and in single cells scattered in the exocrine parenchyma of all three species examined. Using double staining, BDNF IR was seen to be colocalized with glucagon IR in all the species studied. There was a total overlap of BDNF and glucagon IR in duck and lizard pancreas, and partial overlap in mouse pancreas. Our findings suggest that, as well as the primary structure, the presence and pattern of distribution of BDNF in higher vertebrates is also well conserved. Moreover, the abundance of BDNF IR in the pancreas of the species studied leads us to the suggestion that these neurotrophins could regulate the function of pancreatic innervation and/or act on pancreatic cells in a paracrine/autocrine fashion. [ABSTRACT FROM AUTHOR]

Neurotrophins are structurally related proteins that regulate the development, differentiation and maintenance of many neuronal populations. In higher vertebrates (reptiles, birds and mammals) four neurotrophins have been found: nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin (NT) 3 and NT4/5. In the gut, experimental data and the occurrence of neurotrophin receptors in intestinal neurons and endocrine cells suggest neurotrophin involvement in intestinal physiology. However, very few data are available regarding the cellular localization and distribution of neurotrophins in the gut. In this study we report the presence of NGF, BDNF and NT3 in neurons and endocrine cells of mouse, duck and lizard intestine. In particular, immunoreactivity to NGF was observed: (a) in both endocrine and nerve cells of mouse and duck intestine, (b) in endocrine cells of lizard gut. Immunoreactivity to BDNF was seen: (a) in nerve cells of mouse intestine, (b) in very few endocrine cells of mouse and duck intestine. Immunoreactivity to NT3 was detected: (a) in nerve cells of the mouse intestine, (b) in endocrine and nerve cells of duck and lizard gut. Our results, together with data previously reported, on the distribution of specific neurotrophin receptors, seem to suggest a possible paracrine/autocrine mechanism of neurotrophin action in both the enteric nervous system and endocrine cells. [ABSTRACT FROM AUTHOR]