摘要:

The effects of ether and pentobarbital anesthesia on hypothalamic and cere-brospinal fluid (CSF) LH-RH content were studied in male rats. Ether elevated hypothalamic LH-RH 30 min after a 3-min exposure; pentobarbital (30 mg/kg) caused no change. The ether-induced increase in LH-RH content was not affected by pretreatment with pentobarbital; however, the increase was abolished in animals subjected to hypothalamic deafferentation. Changes in CSF LH-RH generally paralleled the hypothalamic changes; ether, for example, elicited a significant rise. These results demonstrate the complex hypothalamo-pituitary-CSF interactions which occur in response to general anesthetics.

ISSN:0028-3835    

DOI:10.1159/000122483

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

GH3 cells which had been exposed for 30 min to [393%). Such preloaded GH3 cells were found able to spontaneously release into the culture medium a radioactive material [3H]-RM) which was analyzed. The kinetics of binding of [3H]-RM to intact GH3 cells and competition with unlabeled TRH were indistinguishable from [3H]-TRH. [3H]-RM was able to stimulate PRL release from GH3 cells. In addition thin layer electrophoresis (TLE) revealed that 90% of [3H]-RM migrated like TRH reference. All these features strongly suggest that [3H]-RM is identical to [3H]-TRH.

ISSN:0028-3835    

DOI:10.1159/000122484

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

In the long-term ovariectomized rat the secretion of LH has a pulsatile character. In such rats no difference was observed between morning and afternoon LH secretion. The administration of phenoxybenzamine, an α-adrenergic blocker, resulted in depressed plasma LH levels. α-Methyl-tyrosine (α-MT), an inhibitor of tyrosine hydroxylase, had no effect on plasma LH levels, whereas bis(4 methyl-1-homopiperazinil-thiocarbonil) disulphide (FLA 63), an inhibitor of dopamine-β-hydroxylase, induced decreased plasma LH levels and disappearance of the pulsations. The same effect was observed after the administration of apomorphine, a dopaminic receptor stimulating drug, whereas the administration of 1-hydroxy-3-amino-pyrrolidone-2 (HA-966), which blocks dopamine release, significantly raised plasma LH levels. Scopolamine, a cholinergic muscarinic receptor blocking drug, had no effect on plasma LH levels, whereas mecamylamine, a cholinergic nicotinic receptor blocking agent, decreased them. These results are consistent with the hypothesis that the pulsatile release of LH in the long-term ovariectomized rat is caused by the stimulating activity of adrenergic and cholinergic, probably nicotinic, systems and the inhibitory activity of a dopaminergic sys

ISSN:0028-3835    

DOI:10.1159/000122485

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Complete isolation or ablation of the medial basal hypothalamus (MBH) was performed in adult male rats, and non-stress prolactin levels were measured by radioimmunoassay in blood collected by decapitation at 24 h, 2 weeks and 6 weeks following surgery. 24 h after surgery, medial hypothalamic ablation (MHA) markedly elevated prolactin levels compared to those of intact control rats; prolactin levels subsequently declined to normal resting values 2 and 6 weeks following surgery. Circulating prolactin levels following hypothalamic isolation were not different from those of controls at either acute or chronic sampling intervals. These data suggest that chronic isolation or destruction of the MBH does not alter basal prolactin secretion in male rats, provided that circadian and stress-induced variations in control animals are properly considered.

ISSN:0028-3835    

DOI:10.1159/000122486

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Rabbits were anesthetized with urethane and were given intracisternal injections of the following substances: adrenocorticotropin, β-melanocyte stimulating hormone, choroid plexus peptide ΠF, epinephrine, serotonin, histamine, oxytocin, lysine and arginine vasopressins, acetylcholine and melatonin. The effects on the concentration of 3’, 5’ cyclic guanosine monophosphate (cGMP) in cerebrospinal fluid were then measured. Only melatonin and acetylcholine caused a significant (p < 0.05) effect on cGMP concentration. Both agents increased the nucleotide’s concentration within 30 min. Melatonin was about 1,000 times more potent than acetylcholine; the minimal effective doses were 1 µg and 1,000 µg, res

ISSN:0028-3835    

DOI:10.1159/000122487

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Daily i.p. injection of reserpine for 9 days strongly depletes hypothalamic norepinephrine (NE); after an initial activation, adrenocortical function returns to control values by the 5th day. Tyrosine hydroxylase (TH) activity in the brain stem of reserpine-treated rats exhibits a progressive increase. Alpha-methyl-para-tyrosine (α-MpT) in rats chronically pretreated with reserpine provokes adrenocortical activation and a further decrease of hypothalamic NE. Exogenous ACTH in the same animals revealed an unimpaired adrenocortical reactivity after prolonged treatment with reserpine. These results seem to suggest that the disappearance of adrenocortical activation following long-term treatment with reserpine is due to the stimulated formation of a small functional pool of NE available for the tonic inhibition of CRF-ACTH secretion

ISSN:0028-3835    

DOI:10.1159/000122488

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

The pineal gland in the rat exhibits a diurnal rhythm in activity of the enzyme serotonin N-acetyltransferase (N-AT) with peak values during the dark period of a diurnal lighting schedule approximately 100-fold those during the light period. After blinding the rhythm becomes free-running. It is abolished by partial hypothalamic deafferentation with a knife cut made caudal to the optic chiasm. Water deprivation for 23 h daily has no effect on the pineal rhythm in either intact, blinded or deafferented animals. In contrast to this, there is a diurnal rhythm in hippocampal formation in norepinephrine content which can be entrained by a water deprivation schedule in both intact and blinded animals. These observations indicate that in the same animals 1 diurnal rhythm may remain entrained to the light-dark cycle while another rhythm is entrained to a secondary synchronizer, the water deprivation schedule.

ISSN:0028-3835    

DOI:10.1159/000122489

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Three weeks after ovariectomy, adult female rats had lower basal levels of serum corticosterone (B), which did not display a daily rhythm, and reduced responses to ether stress, measured by blood levels of B 15 min after ether exposure. Ovariectomized (OVX) females were more sensitive to dexamethasone (DEX) suppression of the ether-induced stress response, reaching basal levels at a dose of 50 µg DEX/100 g b.w. At this dose, B levels were reduced by only 30% over saline-control values in intact rats. DEX-treated intact rats displayed a short-term suppression, reaching a maximum 2 h after the injection followed by a rebound 7 h post-injection and a second suppression period evident by 11 h post-injection. OVX rats showed a steadily increasing suppression that began 1 h after injection and persisted to the last sample time at 11 h post-injection. The disappearance of DEX from peripheral blood was followed by means of radioimmunoassay and no difference was found between intact and OVX rats either in the basal state or 15 min after ether stress. It can be concluded that ovarian steroids condition the sensitivity of the adrenal axis to DEX suppression and that the differences in DEX sensitivity we have previously noted between prepubertal and adult rats can be accounted for by a change in gonadal status rather than by a critical developmental event in the adrenal axis itself

ISSN:0028-3835    

DOI:10.1159/000122490

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Plasma LH and ‘estradiol’ were measured by radioimmunoassay in female rats 5, 10, 15, 20, 25, 30, 40 and 80 days of age, and the changes in these hormone levels 24 h after ovariectomy, ovariectomy plus adrenalectomy, and estrogen injection were determined. Plasma ‘estradiol’ was high at 5 days of age; it increased further to a peak at 15 days of age, and declined thereafter to the low levels seen in adult rats. At each age, plasma ‘estradiol’ declined about 50% 24 h after ovariectomy, whereas it fell to undetectable levels 24 h after ovariectomy plus adrenalectomy at 20 and 80 days of age. Plasma LH did not increase 24 h following ovariectomy at 5 days of age, but it did at all ages thereafter. The peak increase occurred 24 h after ovariectomy at 15 days of age, and the increment was progressively smaller at older ages. Ovariectomy plus adrenalectomy did not cause a significantly greater increase in plasma LH than ovariectomy alone. Injection of estradiol caused a decrease in plasma LH at all ages except in the animals ovariectomized at 5 days of age. The greatest decrease was seen in animals ovariectomized at 15 days of age, with a progressively smaller negative feedback response as age increased. In addition to providing systematic data on changes in the negative feedback effect of estradiol at various ages, the results indicate that, especially in immature animals, there is a circulating substance which cross-reacts with antibodies to estradiol but which does not appear to be a biologically-active estrogen. It does not come from the ovaries and disappears from the circulation if the adrenals as well as the ovaries

ISSN:0028-3835    

DOI:10.1159/000122491

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Effect of monoamine oxidase inhibitor (MAOI) on the induction of persistent estrus by testosterone propionate (TP) was studied in Wistar strain female rats. Daily treatment with MAOI for the 1st 10 days of life accelerated the occurrence of persistent estrus in rats given TP at 8 days of age. The onset of persistent estrus occurred at 57.3 ± 2.0 days of age in these animals compared to 92.6 ± 5.5 days in saline-treated controls. The contribution of hypothalamic monoamines to the induction of persistent estrus by TP treatment in neonatal rats will be discusse

ISSN:0028-3835    

DOI:10.1159/000122492

出版商:S. Karger AG    

年代:1976

数据来源: Karger