In order to analyze whether gossypol has an effect or what effect it has on the hypothalamus, the general structure and morphologic indicators reflecting the neurosecretory function of the neurons of hypothalamic supraoptic, paraventricular and arcuate nuclei were observed in adult male rats following gossypol administration (30 mg/kg/day ? 5 weeks, and 30 mg/kg/day ? 5weeks + 60 mg/kg/week ? 5weeks). Results showed that no marked change in the light-microscopic morphology of the neurosecretory cells of the above mentioned nuclei was found after gossypol treatment for 5 or 10 weeks; and that no significant change appeared in the neurosecretory activity of the three nuclei, according to nuclear volume, contents of Nissl bodies and neurosecretory materials, and activity of thiamine pyrophosphatase and acid phosphatase, merely the Nissl body content in paraventricular nucleus increased after feeding gossypol for 5 weeks. The data indicated that the effective antifertility dose of gossypol had no direct influence on the hypothalamus of adult male rats. It was possible that the temporary increace in the secretory activity of paraventricular nucleus reflected physiologically regulating response of the magnocellular neurosecretory system to some change in the internal milieu of organism caused by gossypol.

The ultrastruetural changes of the cells of adenohypophysis were observed in adult male rats following administration of gossypol at a daily dosage of 30 mg/kg for 5 weeks. The results indicated a remarkable increase in the secretory activity of gonadotrophs. In comparison with the control group, the number of the less actively functioning types Ⅰ and Ⅱ gonadotrophs of gossypol-treated rats decreased, while that of types Ⅲ and Ⅳ cells with developed Golgi complex and dilated rough endoplasmic reticulum increased. Moreover, castration-like cells (type Ⅴ) and degranulation cells (type Ⅵ) appeared in the experimental animals. No significant changes in the other tropic cells of adenohypophysis could be found. The classification of gonadotrophs and the possible mechanism of gossypol-induced changes in them are discussed.

By means of histological and immunohistochemical methods,effects of a singleintraperitoneal injection of ethane dimethanesulphonate(EDS,75 mg/kg bodyweight)on the hypothalamo-pituitary-testicular axis of the rat were observed inthis study.Three days after administration of EDS,Leydig cells were eliminated;some LH cells in pituitary became larger or decreased in immunoreactivity;but nosignificant change could be found in hypothalamic GnRH system.Seven days afterEDS,degeneration of spermatogenic epithelium was marked,the staining intensity ofLH cells was generally reduced,the number of GnRH immunorcactive neurons inthe hypothalamus as well as the density and staining intensity of GnRH fibers andterminals in the median eminence were significantly diminished.Testosteronereplacement increased the number of late spcrmatids in testis and restored theabove-mentioned changes in the hypothalamus and pituitary.These results indicate that following administration of EDS,1)spermatogenesisdamage is resulted from destruction of Leydig cells and cessation of testosterone secretion;2)respective hormone release from hypothalamic GnRH system andpituitary LH cells is increased;3)loss of testosterone negative feedback is themajor factor responsible for the enhancement of secretory activity of the hypotha-lamo-pituitary axis;and that 4)EDS can be a useful experimental tool forstudying hypothalamo-pituitary-testiculer axis and intratesticular local regulation.

Gonadotropin-releasing hormone(GnRH)prohormone of human and rat consistsof GnRH and GnRH-associated peptide(GAP).In this study,three antisera againstN-terminal,mid-region and C-terminal of GAP,and ABC immunoenzyme methodwere used to observe the GAP neurons in the brains of the rat,mouse and guineapig.The distribution of GAP neurons in these animals was similar.GAP perikaryawere mainly present in the septo-preoptic area,with the largest concentration inthe diagonal band near the organum vasculosum of the lamina terminalis.SomeGAP perikarya were also seen in the brain area near the supraoptic nucleus.GAPfibers were widely present in the forebrain and hypothalamus,and terminated inthe organum vasculosum of lamina terminalis and median eminence.Of 3 GAP antisera,the one against N-terminal gave more immunoreactive elements and moreintense staining.The morphology and distribution of GAP perikarya,fibers andterminals were similar to those of GnRH.These results,combined with other relatedfacts,suggest that there is a common GnRH prohormone in mammals,and itsprocessing products,GAP(or cleavage fragments)and GnRH,are cosecreted intohypophysial portal system to regulate anterior pituitary hormone secretion.

The morphology of the GnRH neurons in the rat brain during postnatal development was studied quantitatively using the ABC immunostaining method and an image analyser. The pattern of distribution of the GnRH neurons in different ages animals used was similar. GnRH cells of rats aged 1-7 days were small in size with short processes, pale-stained, and smooth in outline The number of GnRH cells in 1 day rats was not significantly different from that of adult, but a significant decrease in the GnRH cell number appeared in 7 day rats. In postnatal day 14, Gn-RH neurons reached adult level in cell body size, number and staining intensity. The GnRH fibers and terminals in the median eminence were gradually increased and reached adult level up to 14 postnatal days. These results suggested that the number of GnRH neurons is determined shortly after birth; the second postnatal week is the critical period for the development of GnRH neuronal morphology; and the establishment of function of the GnRH neuronal system may be earlier than its morphological maturation.

By means of chromalum-hematoxylin and thiosulfate aldehydefuchsin stains the magnocellular neurosecretory neuron of the rat hypothalamus was studied. The cell body of neuron containing various amounts of secretory granules was large in size, with a variety of shapes. The axon of neuron showed an beaded appearance; only one in each neuron was very fine in diameter and left hypothalamic nuclei to form the hypothalamo-neurohypophyseal tract. The dendrite, in general, thicker than the axon, did not project outside of the nucleus. Many of the thick short dendrites did not contain secretory granules or only few secretory granules. The thick processes with more secretory granules were considered as dendritic processes. A number of axons and thick processes containing secretory granules also contacted with the endothelium of vessels and the ependyma of the third ventricle. In addition, a group of magnocellular secretory neurons were found in the sub-choroid plexuses of the lateral ventricle.

By means of ABC immunoenzyme technique, the distribution of GnRH neurons and fibers in the brains of rats and mice was observed, The results showed that more than 90% of GnRH neuronal perikarya were concentrated in the diagonal band-medial preoptic area near the organum vasculosum lamina terminalis, extending rostro-dorsally to the medial septic nucleus and caudo-laterally to the supraoptic nucleus region. No GnRH cell body could be found in the mediobasal hypothalamus, GnRH fibers terminated in the median eminence via the periventricular and lateral tracts. In the rostral median eminence, fibers were present in its entire layers and width, and caudally separated into two laterally-located bundles. The difference of GnRH system between rodents and primates, as well as its significance in reproduction are discussed.

Gonadotropin-Releasing Hormone (GnRH) immunoreactive neurons in dissociated cell culture from newborn rat hypothalamus were investigated on days 1,3,5,and 7 in vitro by means of the im-munocytochemical method. The results showed that GnRH was expressed in the first day of culture. GnRH neurons accounted for 12.1-14. 8% of the total neurons in culture,and they were mainly bipolar in type. There were growth cones on the end of GnRH processes. Various patterns of intercellular contacts between GnRH neurons and between GnRH and other neurons were also observed. These findings indicate that the cultured GnRH neurons exhibit the morphological and functional characteristics of the GnRH neurons in vivo,and serve as morphological evidence for pulsatile secretion of GnRH and its regulation.

Observations of the ultrastructural changes in neurons of hypothalamie arcuate, supraoptic and paraventricular nuclei were carried out in the rats following gossypol treatment at a dosage of 30mg/kg/day for 5 weeks. The results showed that after gossypol treatment no marked changes in supraoptic and paraventricular cells could be seen at electron microscopic level, and that there appeared a series of ultrastrucrural changes reflecting increased neurosecretory activity in some of arcuate neurons.They were as follows: Golgi complex and rough endoplasmic reticulum were slightlydilated and filled with homogeneous, low electron density materials in their cisternae; the amounts of neurosecretory granules, lysosomes, nucleolus-like bodies, and microtubules were increased. The nature, significance and cause of these changes are discussed.

The distribution relationships of gonadotropin-releasing hormone (GnRH) (5-HT), tyrosine hydroxylase (TH), neurophysin (NP) and ?-endorphin (?-END) in the diagonal band of Broca (DBB) of rat brain were studied by immunohis- tochemistry. The results indicate that there was a close spatial overlap in the distribution between 5HT,TH,NP,?-END fibers and GnRH perikarya and fibers in the ventromedial area of VDBB and dorsomedial area of HDBB. In the dorsomedial area of VDBB close overlap in the distribution between 5-HT fibers and GnRH neurons was also observed. In addition, some TH and NP immunoreactive neurons were found in the medial areas of VDBB and HDBB, The close relationships in distribution and functional significance of GnRH,5-HT, TH, NP and ?-END were discussed.