摘要:

In order to investigate the relation between septohippocampal function and hippocampal corticosterone (B) receptors, discrete septal areas were destroyed by electrolytic lesions; the effects of the lesions on cytosol receptor binding of B in the hippocampus were determined 10 or 30 days after lesioning in male rats adrenalectomized 12 h prior to sacrifice. The septal lesions were also characterized functionally by endocrine, neurophysiological and behavioral parameters in the same group of animals. Hippocampal B receptor activity was increased 30 days after lesioning the lateral septal area. The same lesions impaired the acquisition of a conditioned avoidance response. The increase was not due to a behavioral deficiency per se as lesions in the parafascicular nucleus did impair acquisition behavior without affecting B receptors. There was no change in B receptor activity 30 days after destruction of the medial septal nucleus, although such a lesion completely abolished the hippocampal theta activity measured at 10 days. In another group of animals hippocampal B receptors were not affected at 10 days after any of the lesions, while a transient increase in basal plasma levels of B was noted at that time. It appears that the hippocampal receptor activity for B depends on the integrity of the efferents from the hippocampus and/or the dorsolateral septal B receptor system rather than on the septal afferents to the hippocampus.

ISSN:0028-3835    

DOI:10.1159/000122938

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

In an attempt to mimic the events surrounding the natural onset of puberty in the male rat, animals were castrated and implanted with Silastic capsules filled with testosterone (T). Capsule size was adjusted to maintain serum-luteinizing hormone (LH) at sham-castrated values. To these animals implanted with T capsules, androstenedione (Δ4), 5α-androstane-17β-ol-3-one (DHT), 5α-androstane-3α-17β-diol (3α-OL) or T were administered by subcutaneous injections (40 μg/100 g body weight). 12 h later, the animals received an intravenous injection of 50 ng LH-RH. Pre- and post-LH-RH injection blood samples were assayed for serum content of LH and follicle-stimulating hormone (FSH) by radioimmunoassay. Compared to sham animals, prepubertal males showed a potentiation in the LH response with testosterone alone. This effect was not prevented by Δ4; DHT or 3α-OL injection returned the LH response to that of sham-operated animals. No such effects of androgens were present in pubertal or postpubertal rats. There was no effect on the FSH response in any age group. Different groups of animals received 3 doses of 10 ng LH-RH or saline prior to a single 50 ng LH-RH injection. Pubertal and postpubertal males showed a self-priming effect of LH-RH on the LH response. This effect was not present in prepubertal rats nor in any group of animals that had been castrated, regardless of whether or not T replacement was performed. The results indicate that complex alterations in pituitary function take place during the sexual maturation of the male rat. These changes may be inherent in the pituitary and/or related to variation in testicular androgen

ISSN:0028-3835    

DOI:10.1159/000122939

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The changes in LH and FSH secretion 12, 18 h and 1, 3, 5, 20 and 30 days following castration in adult rats of both sexes neonatally androgenized were studied. After castration, serum LH concentration rose slowly in the female and rapidly in male rats. Orchidectomy induced an increase of LH that was significantly slower in the androgenized rats than in the controls until 20 days after the postcastration period, reaching similar values at 30 days. In the female rats the increase in the LH levels from 48 h to 30 days after castration was significantly lower in the androgenized than in the control rats. Basal levels of FSH were higher in the androgenized males than in the controls. The concentration of the hormone increased in both groups 12 h after orchidectomy, the basal differences disappearing. These groups of rats showed similar values from 48 h up to 30 days after castration. As in the males, FSH basal levels were higher in androgenized rats than in control female rats and the difference disappeared 12 h after castration. The increase in the FSH concentration postgonadectomy was significantly lower in androgenized rats than in the control rats from 48 h to 20 days. At this time, both groups reach a plateau with similar values. These results indicate that androgenized male and female rats showed, at different times of the postcastration period, lower levels of FSH and LH than the controls and that these differences disappear after 30 days of castration. On the other hand, the differences in the basal levels of FSH concentration between controls and androgenized male and female rats also disappear in the first few hours postgonadectomy.

ISSN:0028-3835    

DOI:10.1159/000122940

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Rats with septal lesions and rats with both septal lesions and adrenalectomies (SEP-ADX) acquired avoidance behaviors faster and extinguished these behaviors slower than rats with adrenalectomies or control lesions. Rats with septal lesions also showed increased intertrial crossings during habituation, acquisition, and extinction while rats in group SEP-ADX only had increased intertrial crossings during acquisition. These findings are consistent with the hypothesis that the avoidance performance of rats with septal lesions is a result of neural rather than hormonal factors.

ISSN:0028-3835    

DOI:10.1159/000122941

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Although metergoline (MCE) inhibits prolactin (Prl) secretion in normal and hyperprolactinemic subjects similarly to dopamine (DA) and DA agonists, several data suggest that it acts through a different mechanism, probably as a serotonin antagonist. To further evaluate its Prl-lowering effect, paired sulpiride (Sulp) tests (100 mg i.m.) were performed before and after acute MCE administration (4 mg by mouth 120 min before Sulp) in 10 normal women, while 30 hyperprolactinemic women with pituitary microadenoma and no Prl response to Sulp were studied before and after acute or chronic treatment with either MCE (8–12 mg/day for 1-3 months) or bromocriptine (CB-154) (2.5 mg 300 min before Sulp, or 5 mg/day for 1-2 months), or during DA infusion (5 μg/kg/min for 180 min, Sulp being injected at 120 min). MCE did not alter the Sulp-stimulated Prl release in normal subjects and induced, both after acute and chronic administration, a clear Prl response to Sulp in hyperprolactinemic patients, which did not differ from that occurring in normals. During DA infusion, Sulp induced a marked increase in serum Prl levels, as previously reported in hyperprolactinemic patients without evidence of pituitary tumor; this increase was significantly higher than that observed in normals and in MCE-treated hyperprolactinemic subjects. No Prl response to Sulp occurred in CB-154-treated patients. Basal Prl levels were significantly lowered by all treatments. Although the similarity of effects of MCE and DA on Sulp-induced Prl release might suggest that MCE acts by stimulation of DA receptors, this hypothesis is not supported by pharmacological nor by in vitro and in vivo endocrinological studies; such an action might perhaps be exerted by the drug indirectly via serotoninergic blockade or through hypothetical metabolites. Alternatively, MCE might induce a Prl increase after Sulp in hyperprolactinemic patients by restoring the response of the normal lactotropes, usually suppressed by a central dopaminer

ISSN:0028-3835    

DOI:10.1159/000122942

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The effect of unilateral ovariectomy (OVX) on the weight of the remaining ovary was studied in hypophysectomized (HYPOX) rats. 2 weeks following hypophysectomy + unilateral OVX the weight loss of the ovary is significantly less than that in HYPOX rats having two ovaries. Present data together with previous findings suggest that a neural pathway between the ovaries and the CNS may be involved in the mechanism of compensatory ovarian hypertrophy following removal of one ovary.

ISSN:0028-3835    

DOI:10.1159/000122943

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Ablation of the suprachiasmatic nucleus (SCN) at 2 days of age, prior to the formation of the retinohypothalamic projection, produces a permanent state of constant vaginal estrus in the postpubertal female rat. Although such lesions do not alter the onset of puberty in sighted rats, they do compensate for the delay in vaginal opening induced by neonatal blinding. The ovaries of sighted and blinded SCN-lesion rats are small and polyfoUicular and the pituitaries of blinded SCN-lesion rats are abnormally large. Sampling of plasma in the morning and afternoon for up to 12 consecutive days in sighted SCN-lesion rats reveals continuously low luteinizing hormone levels. This constellation of endocrine alterations does not correlate with damage to any structures outside the SCN. Since the organization of the rodent estrous cycle is circadian, these results emphasize further the importance of the SCN in circadian rhythm generation. The necessity of an intact SCN for the development of normal, cyclic reproductive function implies that sparing or recovery of function does not occur.

ISSN:0028-3835    

DOI:10.1159/000122944

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122945

出版商:S. Karger AG    

年代:1979

数据来源: Karger