摘要:

The content and concentration of sialic acid (N-s Acetylneuraminic acid) and follicle stimulating hormone (FSH) in male rats have been estimated in the anterior pituitary gland during development (from ages 1 to 6 months), at different intervals after castration, and after castration followed by either testosterone propionate (TP) or diethylstilbestrol (DES) treatment. The concentration of sialic acid in the pituitary gland of young male rats is approximately 270 ± 10 µmoles per 100 g. This concentration rises to a peak value at the age of 60 days with a slight fall thereafter. In the adult castrated rats the concentration reaches a maximum of 324.24 µmoles at 21 days after surgery and is followed by an insignificant fall for up to 80 days. Although castration has been found to raise the pituitary sialic acid significantly, it remains unchanged after 200 µg or 2 mg of TP administered subcutaneously daily for 7 days to rats that have been castrated for 21 days. Administration of DES resulted in highly significant reductions in pituitary sialic acid levels in intact as well as in castrated male rats. Radioimmunoassay measurement of pituitary FSH under similar experimental conditions demonstrated a close correlation between FSH and sialic acid concentrati

ISSN:0028-3835    

DOI:10.1159/000122302

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

In vitro, median eminence was found to take up 3H-LRF rapidly, reach equilibrium in approximately 30 min, and achieve an uptake (30 pg LRF/mg) twice that accumulated by anterior pituitary. Conditions which challenged cellular integrity (boiling, treatment with hypertonic saline, etc.) caused marked increases in uptake. Uptake was temperature-dependent and required oxygen and glucose, but was not noticeably ouabain-sensitive. The dissociation of 3H-LRF from median eminence occurred rapidly into media containing a 1,000-fold greater concentration of unlabeled LRF. Estradiol and testosterone, but not corticosterone, significantly inhibited uptake. Unlabeled LRF and TRF, but not MIF, provided significant competition for the uptake of 3H-LRF.

ISSN:0028-3835    

DOI:10.1159/000122303

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Ovarian recrudescence was advanced bytwo months by subjecting the catfish, Heteropneustes fossilis, to a long photoperiodic treatment (14 h/day) for 6 weeks at 25 °C. The precociously gravid catfish were induced to ovulate and spawn with ovine LH. Furthermore, the spawned catfish developed a fresh crop of yolky oocytes when again subjected to long photo-periodic treatment. The temporal changes in the hypothalamo-hypophysial-ovarian system of the spawned catfish were followed at weekly intervals up to day 30. Following induced spawning, the hypothalamo-hypophysial system was activated as shown by the marked degranulation of the neurosecretory nuclei and pituitary basophils on day 7. Vitellogenesis was reinitiated in the ovaries of the spawned catfish and they were gravid by day 21 and 30, and the hypothalamo-hypophysial system was comparable to that of the precociously gravid catfish. The significance of these results is discussed in terms of the existence of a feedback relationship between the hypothalamo-hypophysis and the ovaries

ISSN:0028-3835    

DOI:10.1159/000122304

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Ten lactating Holstein cows were randomly assigned to receive, on 2 consecutive days, either 80 mg ergocryptine (Sandoz-Basel) in 50% ethanol, or 50% ethanol alone. On the day before treatment, serum prolactin in both groups of cows increased from an average of 14–16 ng/ml before milking to 28 ng/ml within 10 min after the application of milking stimuli. Comparable values on the 1st day of treatment were 20 and 35 for control (p < 0.01) and 1.3 and 1.4 for ergocryptine-treated cows. The decrease in serum prolactin after ergocryptine occurred within 2 h and lasted for at least 5 days. Serum cortisol and growth hormone concentrations and daily milk yields were unaffected by ergocryptine treatment. Ergocryptine at doses ranging from 0.01 to 10 µg/ml medium inhibited prolactin but not growth hormone release from pituitary cells cultured in vitro. These results are interpreted as evidence that ergocryptine can decrease serum prolactin in cattle at least in part by a direct effect on the pituitary. In addition, these results indicate that serum prolactin concentrations probably do not directly reflect lactational even

ISSN:0028-3835    

DOI:10.1159/000122305

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Serum LH levels in male and female rats were estimated immediately before and 5, 10 and 20 min after the administration of a standard dose of LH-RH. The effect of estradiol given 3 or 27 h prior to LH-RH was studied. Females were injected with estradiol benzoate on the 1st or 2nd day of diestrus. After an interval of 3 h, the response to LH-RH was blocked in both males and females. In the females, after 27 h the LH levels were high and LH-RH caused an extremely large further increase. In the males, after 27 h the response to LH-RH had returned, although the rise in serum LH was still much smaller than that seen in the estradiol-pretreated females.

ISSN:0028-3835    

DOI:10.1159/000122306

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

To pursue the question of pituitary autonomy, non-stress and stress levels of immunoreactive growth hormone (GH) were determined in serum obtained before and after stress from adult male rats with large medial hypothalamic lesions (MHA). Sham-operated or intact rats served as controls. In experiments performed at various intervals after surgery, blood samples for determinations of non-stress levels of GH were obtained rapidly (<3 min from initial handling) from the jugular vein. In the 1st study, performed 7 days after surgery, stress serum samples also were obtained min following the onset of a 3-min ether stress. In the 2nd study, performed 2, 9 and days after MHA, stress samples were obtained 4 and 20 min after the onset of a 4-min ether stress. Although animals with MHA had non-stress levels of serum GH comparable to those of intact and sham-operated controls, they showed reduced linear growth and an absence of the ether stress-evoked reductions in serum GH levels observed in intact and sham-operated controls. These data indicate that the GH secretion observed by several laboratories following surgical isolation of the medial basal hypothalamus from forebrain is impaired by the ablation of this area. However, considerable GH secretion persists 16 days after MHA.

ISSN:0028-3835    

DOI:10.1159/000122307

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

A fluorescent antibody study of LH-RH-producing cells was made with antisera to synthetic LH-RH in normally cycling female guinea pigs and normal female guinea pigs during the first post-partum cycle. The specifically immunoreactive material, present in the distal segment of the preoptico-infundibular LH-RH neurosecretory pathway, shows significant modifications that are particularly distinct in the ventral labium of the median eminence, with a maximum concentration at the end of diestrus, a sudden fall to a minimum concentration during proestrus and pre-ovulatory estrus, and a progressive increase in concentration during postestrus and diestrus. A parallel is suggested between these modifications and variations in the LH-RH concentration in the median eminence during the estrous cycle.

ISSN:0028-3835    

DOI:10.1159/000122308

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

The distribution of catecholamine-containing nerve terminals has been studied in the cat hypothalamus using a fluorescent histochemical technique. A heavy distribution of catecholamine-containing nerve terminals was found in the supraoptic and paraventricular nuclei. Strongly fluorescent terminals were seen in the dorsomedial, perifornical, and stria terminalis nuclei. Nuclei related to the tubero-infundibular tract also displayed profuse monoamine terminals, especially the infundibular nucleus. The ventromedial nucleus, however, was almost devoid of fluorescent terminals. The infundibular stalk contained numbers of longitudinally-oriented fibers. These fibers terminated around capillaries in the zona externa of the stalk. Cellular fluorescence was not marked. There was fluorescence in some cells of the infundibular nucleus, the supramammillary nucleus and occasional cells in the posterior hypothalamic area.

ISSN:0028-3835    

DOI:10.1159/000122309

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

The participation of the amygdaloid complexes in the stress-induced release of ACTH was studied in the adult male rat. Unilateral and/or bilateral radiofrequency lesions were placed in the amygdalae or their efferent pathways. Plasma corticosterone concentrations were measured after either a leg break, tourniquet, or ether stress. Unilateral amygdaloid lesions did not block the effect of a contralaterally-applied tourniquet or leg break. Bilateral paired amygdaloid lesions blocked the effect of the leg break but not of ether or tourniquet. Bilateral paired lesions between the lateral hypothalamic area and the amygdalae also blocked the effect of the leg break but not ether or tourniquet, whereas bilateral lesions in the anterior portion of the striae terminali did not block the leg-break effect. These data suggest that the amygdalae facilitate rather than directly transmit neurogenic stress-induced signals (leg break) but not signals from systemic stresses (ether). Furthermore, one amygdaloid complex appears to be sufficient for achieving this effect. The pathway from the amygdalae to the hypothalamus involved in the facilitatory effect is probably a direct medial projection to the hypothalamus.

ISSN:0028-3835    

DOI:10.1159/000122310

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

By reversing the regimen of environmental lighting a complete inversion of the diurnal rhythm of pineal N-acetyltransferase was brought about. The nocturnal rise of N-acetyltransferase was rapidly reversed by light, yet the diurnal fall of the enzyme was not affected by darkness. Three days’ exposure of the rats to the reversed light regimen was necessary before a 180° inversion was achieved, producing a 10- to 12-fold increase in day-time (dark period) levels of the enzyme. However, after two days a 3-fold increase in the enzyme was already evident in relation to values of control rats kept on a normal lighting regimen. It is concluded that N-acetyltransferase activity and consequently serotonin and melatonin levels of the pineal, although regulated by an endogenous mechanism in the central nervous system, can be shifted by changes in environmental light which may be synchronizing the endogenous rhyth

ISSN:0028-3835    

DOI:10.1159/000122311

出版商:S. Karger AG    

年代:1974

数据来源: Karger