摘要:

Using an in vivo CRF assay, extra-hypothalamic CRF activity was demonstrated in the peripheral blood of rats bearing extensive ventral hypothalamic lesions. The rats had been hypophysectomized and subjected to laparotomy stress 5 h earlier. CRF activity was not detected in lesioned or lesioned and hypophysectomized animals not subjected to laparotomy stress. CRF activity was assessed by the increment in plasma corticosterone levels produced in the lesioned recipient animals after administration of blood from donor animals. Blood containing CRF activity was ineffective in recipient animals that were both lesioned and hypophysectomized. A direct pituitary CRF action was further demonstrated by the effectiveness of intrapituitary injections of 0.8 µ\ plasma from laparotomy stressed lesioned and hypophysectomized donors. Comparison was made of the time-courses of response to the presumed extra-hypothalamic CRF and the CRF of median eminence origin (ME-CRF). Blood from hypophysectomized rats, containing ME-CRF, elicited an immediate but relatively transient secretion of steroid in the recipient animal, whereas the extra-hypothalamic CRF produced, in addition to the immediate effect, a prolonged elevation of considerable magnitude. Based upon its extreme potency and prolonged time-course of action, the term tissue-CRF was proposed to distinguish it from ME-CRF of hypothalamic origin. Tissue-CRF may be released

ISSN:0028-3835    

DOI:10.1159/000122172

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

A technique employing isolated pituitary cells for the bioassay of CRF is described. The physiological integrity of these cells is indicated by their retention of ACTH against a large concentration gradient under control conditions; and by the release of ACTH in response to appropriate stimuli, through a process which is not only time-dependent, but also requires Ca++, and is inhibited by concentrations of corticosterone found in the plasma of intact rats. Evaluated as a bioassay, the technique is simple, convenient, sensitive and accurate. The evaluation of specificity must await the identification of authentic CRF and its availability for use as a standard.

ISSN:0028-3835    

DOI:10.1159/000122173

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

Monoamine oxidase (MAO) activity was measured in the anterior and posterior hypothalami of male and female newborn intact rats and in animals whose hypothalami were experimentally sexually differentiated. In intact rats, MAO activity was significantly higher in the anterior hypothalamus of male rats at day 12, which was comparable to the females at days 1, 4 and 8. When comparing the anterior to the posterior hypothalamus, an increase in MAO activity in only the anterior hypothalamus was observed in the male rats at day 12, but not before then; in females, MAO activity was always comparable at the same age. When sex was experimentally differentiated through either castration of the newborn male or testosterone treatment in the female, the MAO activity in the posterior hypothalamus remained unchanged. The anterior hypothalamus changed, however, such that a higher level of activity was observed in the female treated with TP and a lesser level in the newborn castrated male. These results support the idea that MAO is involved in the process of sexual differentiation of the brain and that this process basically takes place in the anterior hypothalamus.

ISSN:0028-3835    

DOI:10.1159/000122174

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

In order to study the role of the adrenal cortex in the onset of puberty, female Sprague-Dawley rats were obtained at weaning age and were placed on a 14 h light: 10 h dark cycle. Precocious puberty was produced by means of pregnant mare’s serum gonadotrophin (PMS) given at 22 or 26 days of age. Blood was collected daily at noon or at 8 p. m. by cardiac puncture from alternate groups of rats and assayed for corticosterone (B) by means of a fluorometric procedure. 5 IU PMS at 22 days of age elicited vaginal opening in 20/38 rats on day 24. Evidence of ovulation in these rats was found the following day. A rise in serum B occurred on the morning of day 24 (23.5 ± 1.7 µg% vs. 6.7 ± 0.4 µg% in saline controls) in those rats that ovulated and on the evening of day 23 in those that did not ovulate (26.6 ± 4.8 µg% vs. 11.0 ± 0.8 µg% in saline controls). Facilitation of ovulation with 0.5 mg progesterone at 9 a.m. on day 24 resulted in a depression of B on days 24 and 25, but ovulation occurred in all of the treated rats. The rise in serum B after 25 IU PMS was greater in rats treated on day 26 than in rats treated on day 22. Ovariectomy blocked the response to 25 IU PMS on day 22 but did not prevent the rise in B in animals on day 26. The response to 5 IU PMS was similar in intact and ovariectomized rats at both ages. 25 IU PMS at 4 p.m. on day 26 failed to elevate B to a level comparable to the effects of 25 IU PMS at 9 a.m. on that day. Superovulation, produced by the injection of 25 IU HCG at 9 a.m. on day 29, after 25 IU PMS at 4 p.m. on day 26, suppressed the diurnal rhythm and produced serum B values intermediate between the peak and trough values of other groups. Some recovery was seen by day 33. It is suggested that the change in response to PMS with age may be due to the need for priming levels of adrenocortical hormones to produce ovulation in younger rats treated

ISSN:0028-3835    

DOI:10.1159/000122175

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

Apomorphine, which is believed to stimulate central dopamine receptors, caused a consistent increase in the ovarian weight of immature female rats treated with human chorionic gonadotrophin (HCG). This effect was blocked by haloperidol. Apomorphine also caused an acute depletion of pituitary FSH content in immature female and adult male rats. Pimozide caused a reduction in ovarian weight in HCG-treated rats in seven out of eight treatment groups in two experiments. In only one group, though, was the effect statistically significant. These findings suggest that stimulation of central dopamine receptors may excite FSH secretion. Treatment with phenoxybenzamine or inhibition of the synthesis of catecholamines by α-methyl-p-tyrosine produced variable results and raised problems of interpretation. Treatment with L-dihydroxyphenylalanine caused a consistent increase in ovarian weight in HCG-treated rats. In two experiments this increase was statistically significant, but was prevented or reduced by inhibitors of dopamine β-hydroxylas

ISSN:0028-3835    

DOI:10.1159/000122176

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

A corticotropic hypothalamic area whose lesion led to reduced pituitary-adrenal cortical activity in the pigeon was investigated by means of electrical stimulation with chronically implanted deep electrodes. 300 µA current intensity, 1 msec pulse duration, 60 cps frequency in alternating 10 sec (+) and 10 sec (–) trains over a period of 10 min, as parameters of stimulus, were found to be effective when delivered into the posterior medial lateral hypothalamic region. The plasma corticosterone level sharply increased immediately after the stimulation period and then decreased slowly to the prestimulatory value, 16 min later. Stimulation of other hypothalamic areas with the same parameters did not elicit any change in plasma corticosterone level. Behaviorally, no signs became apparent during the period of stimulati

ISSN:0028-3835    

DOI:10.1159/000122177

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

Orchidectomy produced a rise in plasma gonadotropin levels after 16 h, which was completely prevented by an intraperitoneal injection of DL-α-methyltyrosine (α-MT). When α-MT was injected 18 h after castration, a sharp fall in plasma LH, but not of FSH, followed. L-dihydroxyphenylalanine (l-DOPA) and dihydroxyphenylserine (DOPS) were given to restore catecholamine (CA) or norepinephrine (NE) synthesis, respectively. When given intraperitoneally 16 h after α-MT, the precursors did not alter LH levels; however, plasma FSH was significantly increased by either l-DOPA or DOPS. When α-MT was given 8 h after castration and precursors were injected 30 min later, l-DOPA increased both LH and FSH levels significantly 10 h after injections. When α-MT was injected 18 h after castration and precursors were injected 30 min later, DOPS prevented the fall in plasma LH, but l-DOPA was ineffective. The selective blockade of NE synthesis with diethyl dithiocarbamate (DDC) injected intraperitoneally 18 h after castration at two doses, 500 or 250 mg/kg, markedly decreased LH levels but did not alter plasma FSH. l-DOPA or DOPS, injected 30 min later, did not reverse the effect of the higher dose of DDC; however, when DOPS was injected 15 min after the lower dose of DDC, it partially prevented the decrease in plasma LH. Even at a dose of 200 mg/kg l-DOPA was ineffective. The selective blockade of DA receptors with Pimozide did not alter the rise in LH that follows orchidectomy, but partially blocked the rise of

ISSN:0028-3835    

DOI:10.1159/000122178

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

The correlation between the daily changes of the hypothalamic CRF content and the stages of the estrous cycle was examined in the rat. During proestrus and estrus, the CRF content was significantly higher in the morning (9 a.m.) than in the afternoon (4 p.m.). During diestrus, however, no essential difference was observed. In the morning, the hypothalamic CRF content tended to be higher during proestrus than during diestrus II, but in the afternoon the content was lower during proestrus and estrus, even though the difference did not attain significance. These results, indicating a correlation of daily CRF rhythm with stages of the estrous cycle, are essentially consistent with our previous finding of a sex difference of circadian rhythm of CRF activity in the rat.

ISSN:0028-3835    

DOI:10.1159/000122179

出版商:S. Karger AG    

年代:1973

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122180

出版商:S. Karger AG    

年代:1973

数据来源: Karger