This study examined the stimulating factors for prolactin (PRL) and growth hormone (GH). One aim of the study was to establish an anatomical basis for a proposed releasing factor for PRL, vasoactive intestinal peptide (VIP). Ames dwarf mice, which manifest a spontaneous mutation which, when present in homozygous form (df/df), results in absence of PRL and GH, were used in the present study. Immunoreactive VIP and growth hormone releasing hormone (GHRH) were examined and compared between brains of normal and PRL and GH-deficient dwarf mice in order to see whether there is a response of VIP and GHRH neurons to the absence of target hormones, PRL for VIP and GH for GHRH The anatomical source of the hypophysial portal VIP, and the response of the hypothalamic VIP-containing neurons to PRL deficiency was investigated. VIP immunoreactivity was detected in parvocellular paraventricular nucleus neurons. Groups of VIP-containing neurons in the parvocellular paraventricular nucleus project to the median eminence, which contains portal blood vessels that transport hypophysiotropic factors to the pituitary gland. VIP immunoreactivity was also located in axon terminals in both the external and internal zone of the median eminence. Immunoreactive VIP in the cortex, amygdala, bed nucleus of the stria terminalis, and in the suprachiasmatic nucleus were qualitatively comparable between normal and dwarf mice. Qualitative increases in the fiber immunostaining in the external layer of the median eminence and perikaryal immunoreactivity in PVN of the dwarf mouse were detected. The presence of median eminence-afferent VIP neurons in the paraventricular nucleus and fiber immunostaining in the external layer of the median eminence suggest that parvocellular paraventricular neurons may be involved in PRL regulation Studies of the stimulatory factor GHRH in mice have been hampered by the lack of antiserum directed against the mouse-specific peptide. GHRH-containing cell bodies were found to be primarily concentrated in the arcuate nucleus. In addition, new localizations of GHRH-containing cell bodies were demonstrated, such as in the medial preoptic area, anterior hypothalamic area, and in the area lateral to anterior hypothalamic area. It is not known whether these neurons participate in GH regulation. In addition, GHRH-immunoreactive perikarya in the hypothalamic ventromedial nucleus of dwarf mice were noted. Whether these neurons project to median eminence is not known. The number of the GHRH-containing cell bodies in the dwarf arcuate nucleus was increased compared to the number in normals. The increased number of cell bodies was located in the ventral and medial areas of the arcuate nucleus. (Abstract shortened by UMI.) / acase@tulane.edu
| Identifer | oai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_25986 |
| Date | January 1993 |
| Contributors | Dalcik, Hakki (Author), Phelps, Carol J (Thesis advisor) |
| Publisher | Tulane University |
| Source Sets | Tulane University |
| Language | English |
| Detected Language | English |
| Rights | Access requires a license to the Dissertations and Theses (ProQuest) database., Copyright is in accordance with U.S. Copyright law |
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