摘要:

The role of gonadal hormones in modulating the hypothalamic multi-unit activity (MUA) response to glucose and saline was studied in normal and gonadectomized male and female rats. In intact male rats, unlike intact females, all hypothalamic placements showed either an increase or a decrease in MUA following an injection of glucose. Gonadectomy alone did not produce a significant change in the pattern of hypothalamic response to glucose. Daily injections of estradiol-17β resulted in a significant increase in the number of hypothalamic sites that did not show a glucose-induced change in MUA. In general, the effects on saline tended to parallel those on glucose, although the changes were not as extensive. The results are discussed in terms of estradiol modulation of body weight (b.w.) and of the hypothalamic responsiveness to various stimuli, including glucose and saline injections

ISSN:0028-3835    

DOI:10.1159/000122735

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Four groups of male rats, previously tested for sexual behavior and differing in age and length of time following castration, were examined for the localization of (3H)-testosterone (T) and (3H)-5α-dihydrotestosterone (DHT) in the brain following the injection of (3H)-T. Significant differences existed in the concentration of the 2 androgens among brain regions in all groups. Only in the subcellular particulate fraction from the hypothalami of 1 group castrated for 48 h was there a significant correlation (r = –0.97) between DHT and T levels and pretest mating performance. Though the amount of DHT found in the pituitary was strongly affected by the length of time between castration and sacrifice, no similar effect was found in the bra

ISSN:0028-3835    

DOI:10.1159/000122736

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The effect of microinjection of catecholamines into the 3rd brain ventricle on plasma gonadotropins and prolactin (Prl) titers was evaluated in estrogen and progesterone-primed, ovariectomized (OEP) rats which are a particularly sensitive test animal for LH-RH and the responses compared to those obtained in ovariectomized (OVX), unprimed animals. Intraventricular injection of isotonic saline had no effect on plasma gonadotropins or Prl. The injection of dopamine (DA) into the 3rd ventricle elevated plasma LH in the OEP rats at doses of 4 or 20 µg, but the elevation obtained with the 10 µg dose was not significant. A greater effect was obtained with 20 µg doses of both norepinephrine (NE) and epinephrine (E), with E being the most effective of the 3 catecholamines. Apomorphine (APO) also elevated plasma LH following its injection into the 3rd ventricle in the OEP rats. Since these animals were etherized for removal of blood samples and microinjections into the ventricle, a group of animals was used with in-dwelling cannulae in the external jugular vein. In these animals, DA also elevated plasma LH. In OVX animals, the intraventricular injection of DA was without effect on plasma LH, but small transient increases in plasma LH were obtained with 20 µg doses of NE or E. The action of DA in the OEP rat was not prevented by the prior injection of diethyldithiocar-bamate (DDC) which inhibits NE synthesis. Dopamine, apomorphine, and another DA receptor-stimulating drug, Piribedil (ET-495), lowered plasma Prl following their intraventricular injection in all conditions. There were no effects of any of the drug treatments on plasma FSH. It is concluded that intraventricular DA can stimulate LH release in the steroid-primed rat but that NE and E appear to be more effective in this regard. Epinephrine was the most effective catecholamine in stimulating LH release. Dopamine cle

ISSN:0028-3835    

DOI:10.1159/000122737

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

In anesthetized dogs, perfusion of the cerebral ventricles with indomethacin (IM), an inhibitor of prostaglandin biosynthesis, at rates of 1.9 or 7.6 µg/min was without effect on the plasma ADH concentration. Ventriculo-cisternal perfusion with angiotensin II (All; 19 ng/min) resulted in a 3-fold increase in the plasma ADH concentration within 45 min. When All and IM were perfused together, the plasma ADH concentration increased only 2-fold, a response which was significantly lower than that obtained with All alone. Thus, the ability of central All to stimulate ADH release may depend, at least in part, upon the local release of prostaglandins

ISSN:0028-3835    

DOI:10.1159/000122738

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Lesions of the suprachiasmatic nuclei (SCN) completely eliminated phasic LH release in ovariectomized rats as measured by the positive feedback response to estradiol benzoate (EB)/progesterone or the response to mating. Basal LH levels and the negative feedback response to EB were not affected. Lesions of the medial preoptic area (MPOA) or bed nucleus-dorsal MPOA also inhibited phasic LH release in ovariectomized rats as measured by positive feedback. However, the inhibition was not complete if there was no damage to the SCN, and the degree of inhibition was correlated with the size of the lesion. Basal LH levels and negative feedback were not significantly affected. It is suggested that both the SCN and MPOA are involved in phasic LH release, the former in its role as a neural regulator of circadian rhythms and the latter as part of a diffuse system possibly including estrogen-sensitive and/or LH-RH neurons. Sexual behavior (lordosis) in hormone-primed, ovariectomized rats was not significantly affected by lesions of any structure in the suprachiasmatic-preoptic region.

ISSN:0028-3835    

DOI:10.1159/000122739

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122740

出版商:S. Karger AG    

年代:1978

数据来源: Karger