摘要:

Denervation of the pineal by cervical sympathectomy is equivalent to pinealectomy in blocking the testicular atrophy caused by blinding or exposure of male hamsters to constant darkness. Ganglionectomy, or decentralization of the superior cervical ganglia, was found in this study to block the rise in activity of the pineal melatonin-forming enzyme, hydroxyindole-O-methyltransferase, and the testicular atrophy produced by blinding and constant darkness. These findings provide further evidence for the role or melatonin as a pineal hormone affecting gonadal function in the hamster.

ISSN:0028-3835    

DOI:10.1159/000121995

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

After a preliminary study showed conclusively that in vitro pineal cells avidly take up thyroid hormones but not iodide, a series of tissue slice studies using 125I-thyroxine were conducted to investigate the mechanism of thyroxine (T4) uptake in pineal cells. T4 uptake was unaffected by the presence or absence of glucose and cofactors, nor was uptake inhibited by cyanide. No binding capacity for T4 could be demonstrated, and the percent uptake of labelled T4 actually increased with T4 concentration up to a certain level. Uptake of the thyroid hormone was quite rapid. The temperature coefficient was determined for the uptake, and was found to fall in the range of values reported for diffusion mechanisms. On the basis of these findings, we concluded that energy dependent mechanisms of transport could be eliminated, and that some sort of mediated diffusion was the most likely mechanism for T4 transport.

ISSN:0028-3835    

DOI:10.1159/000121996

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Implantation of crystalline cortisol acetate in the medial basal hypothalamus (MBH), apart from inhibiting pituitary adrenal responses, had a profound suppressive effect on the reproductive system of the immature (30-day-old) rat autopsied 3 weeks after implantation. The development of testes, seminal vesicles, and prostates through the period of puberty was effectively prevented, and spermiogenesis was absent. In the female, estrous cycling was absent, ovarian and uterine development was prevented, and ovulation did not occur. Adrenalectomy in nonimplanted animals had none of these effects. ACTH in doses producing slight to marked adrenal hypertrophy did not influence the changes produced by cortisol implants. It is concluded that cortisol has a direct suppressive effect on gonadottopin secretion at the hypothalamo-pituitary level.

ISSN:0028-3835    

DOI:10.1159/000121997

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Subcellular distribution of exogenous 3H-testosterone was studied in selected tissues of 3-, 11-, and 45-day-old female rats. The relative amount of chloroform extractable (‘free’) radioactivity was significantly greater in the anterior hypothalamus of the 3-day-old rat (17 times more ‘free’ steroid in the 3-day-old than in the 45-day-old at 2 min after injection), and the half-life of radioactivity was longer in the younger animal. It is suggested that sterility following early postnatal steroid exposure may result from the presence of high ‘free’ steroid titers and that protein binding and conjugation may inactivate the hormone in its capacity to produc

ISSN:0028-3835    

DOI:10.1159/000121998

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

The effects of various surgical manipulations in adult male rats were studied in order to determine what effect reductions in sensory stimuli (i.e., light and smell) would have on parameters of growth. Rats that lacked either sight or smell grew subnormally and possessed decreased levels of radioimmunoassayable pituitary growth hormone (GH) when compared with sham-operated rats. If combined sensory deprivation was introduced, very poor growth was observed, with marked reductions in pituitary GH. The pineal gland plays an important role in the regulation of growth in these sensory-deprived rats, since blind-pinealectomized and blind-anosmic-pinealectomized animals showed more nearly normal growth than blind and blind-anosmic rats and possessed greater amounts of pituitary GH than their respective controls. Plasma GH levels, due to their variability, yielded little insight into the growth of sensory-deprived rats. It is concluded that sight and smell are essential for normal growth and that the pineal gland can regulate growth of sensory-deprived rats, either directly by modifying pituitary growth hormone stores or indirectly by way of pituitary gonadotropins or by some other endocrine pathway.

ISSN:0028-3835    

DOI:10.1159/000121999

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

The effects of reserpine and α-methyl-p-tyrosine on the occurrence of vaginal opening were studied in rats. Reserpine decreased hypothalamic norepinephrine content and delayed vaginal opening. However, it also caused a decrease in the rate of body weight gain, and a comparable decrease in body weight gain produced by restricting food intake also inhibited the onset of puberty without reducing hypothalamic norepinephrine content. α-Methyl-p-tyrosine decreased hypothalamic norepinephrine without affecting the onset of puberty. After puberty, the animals treated with both drugs showed periods of prolonged diestrus, indicating that the drugs were affecting the secretion of gonadotropic hormones. These results suggest that brain catecholamines are not involved in the control of vaginal opening in the ra

ISSN:0028-3835    

DOI:10.1159/000122000

出版商:S. Karger AG    

年代:1971

数据来源: Karger

摘要:

Plasma testosterone concentrations in unmanipulated animals gradually increased with age reaching a maximum (11.4 ng/2 ml) at 60 days of age followed by a decrement to a plateau of 3.7 ng/ 2 ml at 90 days of age. Handling or shocking animals, either reweaning or postweaning, had no effects on plasma testosterone concentration in 120-day-old animals. Handling and shocking infant animals altered the developmental pattern of testosterone concentration in peripheral plasma.

ISSN:0028-3835    

DOI:10.1159/000122001

出版商:S. Karger AG    

年代:1971

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122002

出版商:S. Karger AG    

年代:1971

数据来源: Karger