摘要:

The effect of electrical stimulation of the medial preoptic area and arcuate nucleus upon luteinizing hormone release was studied in male rats. Stimulation of either area at 300 µA produced significant increases in plasma LH levels when compared to sham-stimulated controls. Stimulation of the medial preoptic area at 200 µA failed to produce an increas

ISSN:0028-3835    

DOI:10.1159/000122315

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

In female rats treated neonatally with 10 µg estradiol ben-zoate (EB), 250 µg androstenediol-propionate, 250 µg dehydroepiandrosterone (DHEA) or various (10, 50, 250, 1,250 µg) doses of testosterone propionate (TP), we compared the age at which vaginal opening occurred, the incidence of persistent estrus, the ovarian, uterine, adrenal, and pituitary weights, and the pituitary and serum gonadotropin (FSH, LH, prolactin) concentrations. Groups of animals were killed for study at 40, 90 and 150 days of age. EB and 50,250 and 1,250 µg TP given at 5 days of age induced precocious vaginal opening. Although none of the animals given DHEA became anovulatory, 99 % of those treated with the other steroids were in constant estrus by 90 days of age. The only indices measured which could be correlated with the andro-genization treatment were pituitary and serum prolactin. The pituitary prolactin content increased with age in all anovulatory females and was higher than that in animals given DHEA. Serum prolactin was linearly related to both the dose of TP given and the age of the animals. The results are consistent with the view that loss of prolactin-inhibiting control mechanisms of the hypothalamus is a consequence of aging. Whether this is related to a loss of neurons or only a loss of function is unknown. Treatment of the neonate with compounds including estrogens and androgens also causes a loss of function of these neurons and, consequently, the prolactin increase with age is acceler

ISSN:0028-3835    

DOI:10.1159/000122316

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Neural activity was recorded from the pars inter-media of Rana pipiens whose heads were fastened in a moldedplastic holder equipped with fiber optic light guides for the selective illumination of the lateral eyes and the pineal region. The major findings of this study are as follows: Illumination of the eyes influences the discharge of some neurons which terminate in the pars intermedia; Single units which responded to illumination of the lateral eyes were ‘on-type’, i.e. they responded to the onset of illumination with a burst of impulses and discharged at an increased average rate throughout the period of illumination; ‘On-type’ units were binocular, responding to illumination of either the right eye or the left eye individually; The latencies of responses to light suggest that a neural pathway links the retinae of the lateral eyes with the pars intermedia; and Illumination of the pineal region had no detectable effect upon neural activity in the pars intermedia and no effect of illumination could be detected in blinded animals. The results of this study indicate that a neural pathway exists connecting the lateral eyes with the intermediate lobe of the frog pituitary. These observations are consistent with the hypothesis of Hogben and Slome [1936] that the lateral eyes provide the photic information which regulates the output of the pars intermedia, and they provide the most compelling evidence yet obtained for a retinohypophysial neural

ISSN:0028-3835    

DOI:10.1159/000122317

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

The major metabolites from incubat¡on of 14C-progesterone with 700 × g cell-free homogenates of cerebral cortex, hypothalamus and pituitary gland from 5 male ba-boons and 4 male rhesus monkeys were 5α-pregnane-3,20-dione and 2Oα-dihydroprogesterone. Both compounds were identified by their chromatographic properties, derivative formation, reverse isotope dilution methods and recrystallization to constant specific activities. The activities (pmoles h–1 mg–1) of the 20α-hydroxysteroid dehydrogenase, highest in the cerebral cortex of the subhuman primates, exceeded those of the 5α-reductase and did not change in males with sexual maturity. These data from subhuman primates are contrasted to those from rats in which the 5α-reductase activity exceeded approximately 2-fold that of the dehydrogenase in the 3 neural areas studied. In addition, 5β-pregnane-3,20-dione was isolated and identified from the pooled radioactive metabolites from incubation of the baboon neu

ISSN:0028-3835    

DOI:10.1159/000122318

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Iontophoretic application of LH-releasing hormone (LH-RH) elicited changes in the activity of 44 out of 74 MBH units. Each unit was recorded from the neurons which were confirmed to send their axons directly to the median eminence by antidromic activation. The responsiveness of the units to LH-RH fluctuated during the estrous cycle, with a larger percentage of responsive units on proestrus than on diestrus-1. Because estrogen treatment in ovariectomized rats increased the response of the units, this effect of LH-RH might be facilitated by estrogen. On the other hand, only 2 out of 45 medial preoptic (MPO) neurons, which send their axons to the MBH, showed a response to LH-RH. LH and FSH also caused changes in the unit activity in the MBH and MPO. These findings suggest that LH-RH itself may play an auto-regulatory role in the neural control mechanism of LH-RH secretion into the pituitary portal vessel. The responses of MBH and MPO neurons to LH and FSH seem to imply that these neurons may participate as sensitive components of the central nervous system in the feedback control mechanism of gonadotropins.

ISSN:0028-3835    

DOI:10.1159/000122319

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Castration of male rats immediately afterbirth, which induces a permanent femininization of reproductive function, resulted in a marked reduction in the weight and total organ content of norepinephrine in the vasa deferentia as measured before and after sexual maturation. The norepinephrine fall was about 3-fold greater than after castration of adult animals. Androgenìzation of female rats by a single injection of testosterone propionate on the 5th day post partum did not affect uterine weight, but significantly lowered total organ content of norepinephrine when measured before and after sexual maturation. It is suggested that the vasa deferentia and uterus contain a population of adrenergic nerves, probably identical with or part of the system of ‘short adrenergic neurons’ that constitute a separate target system for those humoral factors which determine the pattern of development of the reproductive tract by influencing the early differentiation of the hypothal

ISSN:0028-3835    

DOI:10.1159/000122320

出版商:S. Karger AG    

年代:1974

数据来源: Karger