Expression of Nerve Growth Factor and its Receptors trkA and p75 and Inhibin .ALPHA.-Subunit in the Ovarian Interstitial Cells of Lactating Golden Hamsters

Abstract

Abstract. Characteristic daily increases in the plasma levels of luteinizing hormone (LH) are present every afternoon during lactation in golden hamsters. The objective of this study was to investigate the effect of the diurnal rhythm of increases in LH on expression of nerve growth factor (NGF), its receptors trkA and p75 and inhibin α-subunit in the ovarian interstitial cells of lactating golden hamsters. Both lactating and non-lactating groups of postpartum golden hamsters were used in this study. The expression of NGF, its receptors trkA and p75 and inhibin α-subunit were determined by immunohistochemistry. Positive staining of NGF, trkA and p75 was found in the interstitial cells of the lactating group, and no immunoreactivity for NGF, trkA or p75 was observed in the ovarian interstitial cells of the nonlactating group. In addition, immunostaining of inhibin α-subunit was also observed in the interstitial cells of the lactating group but not in those of the non-lactating group. Immunostaining of the inhibin/activin βA-and βB-subunits was observed in the granulosa cells of antral follicles, but not in the interstitial cells of the lactating and non-lactating animals. These results suggest that the diurnal rhythm increases in LH can induce expression of NGF, trkA, p75 and inhibin α-subunit in the ovarian interstitial cells of lactating golden hamsters and that NGF, its receptors trkA and p75 and inhibin α-subunit may have the capacity for autocrine or paracrine modulation of interstitial cell differentiation in golden hamsters. Key words: Golden hamster (Mesocricetus auratus), Inhibin α subunit, Interstitial cell, Nerve growth factor (NGF), p75, trkA (J. Reprod. Dev. 54: [397][398][399][400][401] 2008) he nerve growth factor (NGF), a 26-kDa polypeptide [1], belongs to a family of related proteins required for the survival, maintenance and development of discrete neuronal populations in the central and peripheral nervous systems [2,3]. The effect of NGF has been shown to be mediated through specific membrane receptors high-affinity tyrosine kinase A (trkA), and it is responsible for the biological activities of NGF [4,5]. Furthermore, the effect of NGF is also mediated via low affinity p75 receptor and it is also other neurotropins receptor [6]. It is now well known that NGF and its receptors are expressed in the mammalian ovary. More and more evidence indicates that NGF and its receptors play a critical role in development of the mammalian ovary, oogenesis and folliculogenesis [7][8][9][10][11][12][13].Inhibin/activin subunits are present in numerous mammalian tissues of both endocrine and nonendocrine organs. The dimeric proteins formed from the subunits are members of the transforming growth factor (TGF) β superfamily of growth and differentiation factors and have been isolated and characterized as gonadal peptides. Inhibins and activins are structurally related dimeric gonadal proteins with the ability to regulate follicle stimulating hormone (FSH) secretion from pituitary glands [14]. They are also dim...

Immunodetection of NGF, trkA, p75 and Inhibin .ALPHA.-Subunit in Interstitial Cells of Golden Hamsters Treated with hCG

“…Studies in golden hamsters have shown that NGF and its two receptors trkA and p75 are present in the ovary and uterus, demonstrating that NGF and its receptors trkA and p75 have important autocrine and paracrine regulatory roles in ovarian and oviductal function and uterine growth and proliferation during the estrous cycle [21,[32][33][34]. In our previous studies, NGF and its two receptors trkA and p75 were observed in numerous interstitial and luteal cells of golden hamsters [32].…”

“…Inhibin production is restricted mainly to steroidogenic tissues and the hypophysis, whereas activins are produced in many cell types and organs [24][25][26]. It is now clear that inhibin/activin subunits could exert local autocrine and paracrine roles on steroidogenesis and folliculogenesis within developing ovaries [27][28][29][30][31].Studies in golden hamsters have shown that NGF and its two receptors trkA and p75 are present in the ovary and uterus, demonstrating that NGF and its receptors trkA and p75 have important autocrine and paracrine regulatory roles in ovarian and oviductal function and uterine growth and proliferation during the estrous cycle [21,[32][33][34]. In our previous studies, NGF and its two receptors trkA and p75 were observed in numerous interstitial and luteal cells of golden hamsters [32].…”

Immunolocalization of NGF and its receptors in ovarian surface epithelium of the wild ground squirrel during the breeding and nonbreeding seasons

“…NGF and its receptors, under the influence of gonadotropins and/or ovarian hormones, play a crucial regulatory role in these processes. 32-34 The roles of NGF and its receptors in ovary of the wild ground squirrel have been studied, indicating in situ synthesis and secretion of NGF and its receptors in ovaries of the wild ground squirrel, where the role of NGF might be mediated via both receptors TrkA and P75 to affect follicular development. 25 Moreover, the expression levels of NGF and its receptors, TrkA and p75, were significantly higher in the breeding season compared to the nonbreeding season, suggesting that the NGF system may be involved in the regulation of ovarian function changes.…”

Immunolocalization of NGF and Its Receptors trkA and p75 in the Oviducts of Golden Hamsters during the Estrous Cycle

“…NGF and its receptors, under the influence of gonadotropins and/or ovarian hormones, may play a crucial regulatory role in these processes. The roles of NGF and its receptors in the ovary, uterus, and ovarian interstitial cells of golden hamsters have been studied, and these roles and the modulation of expression of NGF and its receptors differs among the various reproductive tissues [21,22,26]. In the ovarian tissues of golden hamsters, immunopositive reactions of NGF and its receptors were found in oocytes, theca and granulosa cells of different sized follicles [22].…”

“…Positive reactions for NGF and its receptors were also present in interstitial cells during the estrous cycle. Furthermore, the LH surge may be an important factor for stimulating the production of NGF and its two receptors in the interstitial cells of the golden hamster [26]. NGF and its two receptors are present in uteri of golden hamsters and their expression is stimulated by estrogen and progesterone [21].…”