ISSN:0028-3835    

DOI:10.1159/000122032

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

Changes in electrical activity of the brain were studied in 34 Wistar female mature rats (including 3 rats with retrochiasmatic section), following electrical stimulation of the uterine cervix on the day of estrus to induce pseudopregnancy. The macro-micro electrodes were chronically implanted into the various areas of the brain and the multiple unit activity (MUA) was recorded with no behavioral restraint. The results are summarized as follows: For several hours after the cervical stimulation (CS), the MUA in the arcuate nucleus (ARC) decreased, whereas that in the anterior hypothalamic area (AHA) and dorsomedial hypothalamic nucleus (DMH) increased. In contrast, from the 1st day until at least the 4th day, the MUA in the ARC increased, except in the frontal section 6.6 of Albe-Fessard’s atlas, while the MUA in the AHA and medial preoptic area (MPO) decreased. The MUA in the ventromedial hypothalamic nucleus (VMH) decreased immediately following or at least 2 days after the CS. From the 4th day of pseudopregnancy, the DMH, AHA, and hippocampus (HPC) showed a decrease in their MUA. CS failed to establish pseudopregnancy in rats with retrochiasmatic section. In such rats, the MUA in the ARC and AMYG showed almost no change, except for a slight and transient decrease immediately after the stimulation. The bursts of MUA characteristic of cyclic rats were not observed in the pseudo-pregnant rats; when the CS failed to induce pseudopregnancy, the characteristic bursts of MUA were suppressed for about 4 days. Afferent impulses caused by the CS may be conducted to the hypothalamic areas through anterior rather than posterior connections. The MUA changes observed for 3 or 4 days after stimulation seem to represent the brain activity that participates in the establishment of pseudopregnancy. Hormones related to the maintenance of pseudopregnancy, such as prolactin, progesterone, estrogen, and others, may cause the MUA changes on the 4th day of pseudopregnancy and, thereafter, by their feedback actio

ISSN:0028-3835    

DOI:10.1159/000122033

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

The effects on FSH secretion of systemic injection or implantation of testosterone into the hypothalamopituitary region were evaluated in normal and castrated male rats. FSH was assayed by the method of Steelman and Pohley. Injection of 4 mg of testosterone propionate s.c. every other day for 35 days increased pituitary FSH concentration and content and reduced anterior pituitary weight in both normal and castrated rats. There was an increase in weights of seminal vesicles and prostates. In castrates, the androgen lowered plasma FSH levels. Bilateral implants of testosterone in the anterior pituitary mimicked the response to systemic injection of the steroid, since pituitary FSH content and concentration were increased and pituitary weight was decreased. Plasma FSH was lowered in castrates by the pituitary implants of testosterone as well. Single midline median-eminence implants of the steroid were ineffective in altering pituitary FSH in normals or castrates and failed to lower plasma FSH in castrates. Implants of testosterone in the hypothalamopituitary region did not modify testicular or accessory sex organ weights. It was concluded that testosterone can inhibit FSH secretion in the male rat by a direct action on the anterior pituitary.

ISSN:0028-3835    

DOI:10.1159/000122034

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

Hypothalamic follicle stimulating hormone releasing factor (FSHRF) content, pituitary and plasma follicle stimulating hormone (FSH) concentrations have been determined in female rats between 5 and 75 days of age. FSHRF was present by at least 10 days of age and at levels that exceeded those observed at any age thereafter. No fluctuations in FSHRF were detected during the estrous cycle. Plasma FSH levels determined by radioimmunoassay increased threefold between 5 and 15 days of age, at which time, values were approximately 1,300 ng/ml. At no other age were levels of this magnitude observed. During the estrous cycle, values ranged between 136 and 261 ng/ml, with the lowest during the morning of proestrus and the highest, the morning of estrus. Pituitary FSH stores during the cycle determined by bioassay were 16.5 (proestrus), 19.5 (estrus), 22.8 (metestrus), and 21.2 µg (diestrus) per pituitary. Neural regulation of FSH secretion exists by at least 10 days of age in the female rat. FSH secretion decreases between 15 days of age and puberty, and fluctuates at least twofold during the adult cycle

ISSN:0028-3835    

DOI:10.1159/000122035

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

In a retrospective study of 952 skull X-rays taken in a few Lagos hospitals, it was found that the over-all incidence of calcification of the pineal gland was surprisingly low: 5.04% compared with the high incidence of 33-76 % reported in studies on other population groups. The incidence among the decades, and between the sexes, and the correlation with clinical diagnoses are analysed. The possible physiological and radiological implications are discussed.

ISSN:0028-3835    

DOI:10.1159/000122036

出版商:S. Karger AG    

年代:1972

数据来源: Karger

摘要:

It has previously been shown that plasma radioimmunoassayable growth hormone (GH) falls following exposure to cold. This response was examined in the normal, adrenalectomized, thyroparathyroidectomized, and adrenalectomized-thyroparathyroid-ectomized rat to determine the effects of the absence of corticosterone (B) and of the thyroid and parathyroid glands on this response. GH decreased from a high prestress level to a low poststress level in both the normal and adrenalectomized animal. The thyropara-thyroidectomized and the adrenalectomized-thyroparathyroidectomized rats had a low prestress GH level, which was not decreased further following cold exposure. The prestress B levels were higher in the thyroparathyroidectomized animals than in the normal. Poststress levels of B were similar in both groups. It appears that an intact thyroid and/or parathyroid gland is necessary to maintain the normal resting plasma levels of GH and B, whereas stress levels do not appear to be affected.

ISSN:0028-3835    

DOI:10.1159/000122037

出版商:S. Karger AG    

年代:1972

数据来源: Karger