摘要:

This study notes the effects ofsocial stress upon growth, adrenal gland weight and pituitary MSH levels in male mice. Mice were placed in cages containing varying numbers of animals. After 2 weeks it was observed from bites on the tail and external genitalia that some mice had been subjected to visible social stress (fighting) although others had not. Each stressed mouse was rated on a scale ranging from 0 (unstressed) to +4 (severe stress). Comparing stressed to unstressed mice, it was determined that stressed mice (1) had a much smaller average body weight gain, (2) had larger adrenal gland weights, and (3) showed a significant elevation in pituitary MSH content.

ISSN:0028-3835    

DOI:10.1159/000122547

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

All experiments utilized blood samples obtained bychronic right atrial catheters. Growth hormone measurements, made by specific radioimmunoassay, showed that fasting and estrogen ad-ministration result in increased growth hormone secretion in the rabbit, although physical stress and exposure to cold do not. Insulin-induced hypoglycemia after fasting caused a decline in plasma growth hormone, and arginine infusion in the estrogen-primed rabbit resulted in an initial depression of plasma growth hormone followed by a renewed secretory phase. Electrical stimulation in the vicinity of the ventromedial nucleus of the hypothalamus caused an abrupt rise in serum growth hormone.

ISSN:0028-3835    

DOI:10.1159/000122548

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Plasma LH was measured by radioimmunoassay inblood withdrawn through atrial cannulas at 10-min intervals in long-term ovariectomized (OVX) rats. A subcutaneous (s.c.) injection of estradiol benzoate or an intravenous (i.v.) injection of 17β-estradiol inhibited the pulsatile discharge of the hormone and depressed the plasma LH concentration. Neither progesterone nor small amounts of rat prolactin altered the pulsatile rhythm or lowered plasma LH levels. A s.c. injection of nicotine tartrate at a dosage which blocks the pro-estrous rise of LH caused a marked depression in plasma LH concentration. In rats which still exhibited pulsatile LH release after being subjected to partial or total deafferentation of the medial basal hypothalamus (MBH) 4–6 weeks prior to ovariectomy, injections of estradiol benzoate, 17β-estradiol and nicotine gave results similar to those seen in non-deafferented OVX animals. 17β-estradiol had a partial inhibitory effect on pituitary LH release in response to an injection of synthetic LHRH. The results suggest that the inhibitory effects of estrogen and nicotine on LH release are exerted via blockade of LHRH discharge from the MBH and that estrogen also inhibits LH release by an action on the adenohypoph

ISSN:0028-3835    

DOI:10.1159/000122549

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

The disappearance of radioactivity after the injection of 14C-labeled-Pro-Leu-Gly-NH2, an MSH release-inhibiting factor (MIF-I), was measured in rats which had been subjected to various procedures. Delayed disappearance of the radioactivity to a small but statistically highly significant extent was found in hypophysectomized rats compared to rats with an intact pituitary. Pinealectomy and adrenalectomy did not change the half-time disappearance. Dehydration, hypothalamic destruction, or administration of excess saline, MSH, and large amounts of unlabeled MIF-I were all used as control procedures. These failed to demonstrate the mechanism by which the prolonged disappearance occurred, but did raise other questions. The half-time disappearance of tritiated inulin was not significantly different in hypophysectomized or intact rats. The results indicate that the absence of the pituitary gland prolongs the half-time disappearance of radioactivity from the blood of rats injected with labeled MIF-I.

ISSN:0028-3835    

DOI:10.1159/000122550

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Serum prolactin levels following ether anesthesia and laparotomy were measured in intact, cyclic rats which were injected daily, beginning on the first day of diestrus, with either oil or with 2 (P2) or 10 mg (P10) of progesterone. A single P2 or P10 injection affected neither the basal (decapitation) nor the ether-laparotomy serum prolactin level. Six days of treatment, however, reduced the ether-laparotomy-induced in-crease in the prolactin level, but had no effect on the basal level. Ovariectomized rats were also injected daily for 6 days, beginning on the 14th post-castration day, with either oil, P10,0.01 (E 0.01) or 0.25 µg (E 0.25) of free estradiol, or a combination of either E 0.01 + P10 or E 0.25 + P10. No significant differences in the serum prolactin levels were found between the rats killed by decapitation and those subjected to ether-laparotomy in any of these groups. Treatment with P10, however, significantly lowered the serum prolactin level although treatment with E 0.25 raised it. P10 treatment also reduced the estrogen (E O.25)-stimulated elevation in the prolactin level

ISSN:0028-3835    

DOI:10.1159/000122551

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

The present study was devoted to the recording ofspontaneous multiple-unit discharges in the pineal gland of the quail to investigate the influence of light stimulation on the multiunit pineal activity. The spontaneous rate of firing depended upon the size of the macro-microelectrodes (86 spikes/10 sec with 30 µm electrodes; 25 spikes/10 sec with 15 µm electrodes). Light flashes resulted in a marked inhibition of electrical discharges recorded from the same cell populations (54 vs 86 and 14 vs 25 spikes/10 sec). A bilateral section of optic nerves suppressed the inhibiting response of pineal activity to illumination and allowed the spontaneous firing rate to be increased almost 4-fold in blinded quail compared to intact control

ISSN:0028-3835    

DOI:10.1159/000122552

出版商:S. Karger AG    

年代:1974

数据来源: Karger