摘要:

Pituitary TSH (McKenzie bioassay), hypothalamic(HTH) TRF-like activity, and pituitary responsiveness to TRF were determined in fetal (18th–22nd days gestation), infant (0–23 days of age), and adult rats. Pituitary TSH concentration in-creased 10-fold between the 18th and 22nd days of gestation and, after birth, increased further to adult levels by 1 week of age. Fetal and neonatal pituitaries were capable of releasing TSH when incubated in vitro with TRF-like material extracted from the HTH of adult donor rats. HTH TRF-like activity was measured by its ability to release TSH from test mice in vivo and from donor rat pituitaries in vitro. TRF-like activity was present in the HTH of fetal rats in low concentration (20% of that in adults) and increased to adult levels by the second postnatal week. Thus, the capacity of the HTH to produce TRF and that of the pituitary to respond to TRF are present before birth and throughout the neonatal per

ISSN:0028-3835    

DOI:10.1159/000122133

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

Intracellular recording techniques havebeen used to measure transmembrane potentials (TMP), membrane resistance, and membrane capacitance from individual cells in the rat adenohypophysis in vivo. Transmembrane potential and membrane resistancewere monitored following intracarotid injection of hypothalamic stalk-median-eminence (HSME) extract. The injection of the equivalent of 1 rat HSME resulted in a transient alteration in TMP in only a small proportion of the cells, but produced a consistent and reproducible increase in membrane resistance in the majority (77%) of cells. The results suggest that cells in the adenohypophysis may be coupled with low resistance intercellular bridges. Releasing factors may function to uncouple cells.

ISSN:0028-3835    

DOI:10.1159/000122134

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

Bilateral implantation of small amounts of progesterone in the amygdala, cerebellum, and median eminence of castrated female rats results in an increase of pituitary stores of LH and in a decrease of hypothalamic stores of LH-RF. Similar implants placed subcutaneously or in the cerebral cortex are ineffective. It is suggested that the amygdala and the cerebellum contain receptors sensitive to progesterone and intervene in modulating the negative, inhibitory effect that this steroid exerts onLH secretion.

ISSN:0028-3835    

DOI:10.1159/000122135

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

An experiment was performed to determine the effectof sodium deprivation on pituitary and plasma radioimmunoassayable proiactin, growth hormone and thyrotropin, aldosterone and total corticosteroid secretory rates, plasma corticosterone, pineal, adrenal and body weights, serum sodium and hematocrit. Compared to the results in control animals, sodium deprivation pro-duced increased aldosterone secretory rates, increased plasma and pituitary proiactin levels, lower serum sodium, higher hematocrit, and lower body weight. The evidence is interpreted as indicating that pituitary proiactin secretion is essential in enhancing the aldosterone secretory response to sodium deprivation.

ISSN:0028-3835    

DOI:10.1159/000122136

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

Daily injections of epinephrine, 1-dopa, or iproniazid for 25 days into 20- to 23-month-old constant estrous Sprague-Dawley rats initiated regular estrous cycles in most rats. On termination of treatment, a few rats continued to cycle but the majority returned to a state of constant estrus or went into a prolonged diestrus. It is concluded that all three drugs restored regular cycling in old constant-estrous rats by correcting a catecholamine deficiency in the hypothalamus, thereby increasing release of LH and FSH and decreasing release of prolactin.

ISSN:0028-3835    

DOI:10.1159/000122137

出版商:S. Karger AG    

年代:1973

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122138

出版商:S. Karger AG    

年代:1973

数据来源: Karger