摘要:

When made during the morning of proestrus, small cuts, situated posterior to the anterior commissure, advance the timing of the pre-ovulatory gonadotropin secretion by about two hours. It is suggested that this phenomenon is caused by the removal of the hippocampal influence on gonadotropin secretion by transection of the medial cortico-hypothalamic tract.

ISSN:0028-3835    

DOI:10.1159/000122295

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Relatively large doses of alpha methyl paratyrosine (α-MPT) (400 mg/kg, i.p.) to inhibit catecholamine synthesis were capable of blocking both the pre-ovulatory elevation in plasma LH and ovulation in proestrous rats. Similarly, large doses of diethyldithio-carbamate (DDC) to deplete brain norepinephrine stores also inhibited ovulation and LH release. The blockade induced by α-MPT could not be reversed by the administration of L-dihydroxyphenylalanine (L-dopa) or dihydroxyphenylserine (DOPS). Similarly, neither L-dopa nor DOPS was able to alter the blockade induced by DDC. An injection of progesterone (2 mg/rat, s.c.) increased the plasma LH values on the afternoon of proestrus and the stimulatory effect of progesterone was blocked by the administration of α-MPT prior to progesterone. Although L-dopa failed to reverse the blockade of α-MPT, a partial reversal was obtained by the administration of DOPS. DDC also blocked the progesterone-induced LH release and there was a slight reversal in animals given DOPS together with DDC. Except for the difficulties in reversing the blockade with drugs to augment norepinephrine synthesis, the results are consistent with the hypothesis that norepinephrine is involved in the pre-ovulatory discharge of gonadotrop

ISSN:0028-3835    

DOI:10.1159/000122296

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

The relationship between the neonataltestes and the functional development of the hypothalamo-hypophysial system of the male rat was studied. Males were castrated on day 3, 4, 5, 8 or 10 of life. At 40 days of age one-half of an ovary from a littermate was grafted under the kidney capsule. 20 days after transplantation into males castrated on days 3 to 8, the histology of the ovarian grafts showed a relative abundance of corpora lutea, indicating the development of the female-specific functional pattern of the hypothalamo-hypophysial system. After 10 days, in spite of castration, the hypothalamo-hypophysial system was of the male-specific type. Castration and the simultaneous transplantation of ovaries in the abdominal region caused a significant increase in the weights of the anterior pituitary and the seminal vesicles.

ISSN:0028-3835    

DOI:10.1159/000122297

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Intra-arterial injections (8–75 mg/kg) of L-3,4, dihydroxyphenylalanine (L-dopa) at 1 p.m. on the afternoon of proestrus produced a rapid increase in serum LH in unanesthetized female rats. Maximum responses were observed following doses of 25 mg/kg although the smallest (2.7 mg/kg) and largest (225 mg/kg) doses were ineffective in stimulating LH release. Pentobarbital anesthesia (40 mg/kg, i.p.) at 12.30 p.m. on proestrous prevented the responses to L-dopa. The 25 mg/kg dose of L-dopa, which produced maximum effects in the unanesthetized proestrous rat, caused no detectable LH release in unanesthetized diestrous rats. These results support the concept that dopaminergic mechanisms are involved in the pre-ovulatory release of LH and indicate that two of the conditions which prevent spontaneous pre-ovulatory LH release (pentobarbital anesthesia or a lack of circulating estrogens) may similarly inhibit L-dopa-mediated LH releas

ISSN:0028-3835    

DOI:10.1159/000122298

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

The CRF-like activity of peptides related to vasopressin and oxytocin was estimated using a semi-automated in vitro bioassay. Rat pituitary halves were incubated for 1 h with the test material in 1.0 ml of Krebs-Ringer bicarbonate buffer. The ACTH released from the pituitary tissue was estimated using adrenal quarters in an automated superfusion system. The pituitary tissue was standardized with median eminence extract, and adrenal tissue was standardizeed with ACTH. Vasopressin and its analogues release ACTH in order of their pressor potency. Most of the ring or tail fragments of oxytocin and vasopressin did not stimulate the release of ACTH. In some experiments, deaminopressinamide and pressinoic acid had CRF-like activity.

ISSN:0028-3835    

DOI:10.1159/000122299

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Luteal function in the Mongolian gerbil (Meriones unguiculatus) has been examined by pituitary homografting and hypothalamic lesioning. It was found that luteal maintenance, as determined by the decidual reaction, could be achieved in gerbils bearing either hypothalamic lesions or multiple pituitary grafts. These results suggest that the luteotrophic complex of the gerbil, like that of the rat, is subject to inhibitory control by the hypothalamus.

ISSN:0028-3835    

DOI:10.1159/000122300

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

We have previously reported that immobilization stress administered twice daily over a one-week period results in delayed puberty and reduced fertility in C57/B16 mice exposed to the stress prior to or at the onset of puberty. Exposure to the same stress in adult cycling or non-cycling females led to larger litter sizes and a greater incidence of conception. The purpose of the present study was to determine whether the effects of stress on fertility were associated with changes in the amplitude or rhythm of corticosterone concentration in the blood. Prepubertal mice subjected to daily immobilization stress showed a shift in the peak of the daily corticosterone rhythm which persisted for at least a week after the stress periods were terminated. In adult female mice housed near males in order to maintain an estrous cycle, the same stress caused a reversal of the daily corticosterone rhythm with peak levels of corticosterone occurring during the midpoint of the light interval rather than shortly after the onset of darkness. Old females maintained in large groups and showing no evidence of regular estrous cycles had no evidence of a 24-h corticosterone rhythm before stress. During the week after stress had been discontinued these mice developed a daily rhythm. It can be concluded that in mice the presence of adrenal rhythm is associated with fertility and the absence of such a rhythm is correlated with infertility.

ISSN:0028-3835    

DOI:10.1159/000122301

出版商:S. Karger AG    

年代:1974

数据来源: Karger