摘要:

With the purpose of identifying the neural structures which are involved in the mediation of the adrenocortical responses to photic, acoustic and sciatic nerve stimulation, experiments were conducted on male rats with bilateral section of the dorsal fornix and dorsal or ventral hippocampectomies. The basal corticosterone levels in these animals were not significantly different from those in controls. Stimulation of the 3 sensory modalities produced normal adrenocortical responses in rats with fornix section. The hippocampectomies had no effect or only a marginal effect on the response to ether stress and to photic and acoustic stimulation; however, the adrenal response to sciatic stimulation was very significantly reduced. The data demonstrate the participation of the hippocampus in the transmission of somatosensory responses which promote adrenocortical activity. The efferent connections of the hippocampus to the hypothalamus which are involved in this mechanism are discussed.

ISSN:0028-3835    

DOI:10.1159/000122607

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

S.c. introduction of silastic capsules containing estradiol-17β (E2) in the ovariectomized rat causes a surge of luteinizing hormone (LH) on the following day. The levels of cytoplasmic and nuclear E2 receptor complex were measured in the pituitary and hypothalamus at 0, 9, 24 and 33 h intervals after placing the E2 implant. The pituitary sensitivity to exogenous gonadotropin releasing hormone (GnRH) with respect to LH release in vitro was also measured. The results suggest that: (1) the pituitary sensitivity to exogenous GnRH remained higher 9, 24 and 33 h after placing the implant; (2) the circulating LH level decreased at 24 h and then increased at 33 h; (3) the pituitary and hypothalamic E2 receptor levels show striking differences during E2-induced LH release. Thus, the relationship between pituitary sensitivity to exogenous GnRH and the E2 receptor level in the pituitary and hypothalamus is complex

ISSN:0028-3835    

DOI:10.1159/000122608

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

The presence and production of cyclic 3’, 5’-adenosine monophosphate (cAMP) were investigated in the hypothalamus and neural lobe of the rat. Theophylline (concentrations from 10–3 to 8 × 10–3 M) increased the in vitro content of cAMP in the isolated neural lobe and in hypothalamic tissue samples containing supraoptic (SO) or paraventricular (PV) nuclei. Acetylcholine (ACH; 10-2 and10–4 M) or carbachol (10–4 M) did not increase cAMP content in the isolated neural lobe. Small increases were apparent (p < 0.05, t-test for paired samples) in the hypothalamus. The amounts of cAMP were significantly higher in isolated neural lobes but not in hypothalami of NaCl-treated or lactating as compared to control rats. Presence of cAMP in the neural lobe and activation of adenylate cyclase under stimulated hormone release conditions indicate a possible involvement of cAMP in the process of neurohypophysial hormo

ISSN:0028-3835    

DOI:10.1159/000122648

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

The effect of electrochemical stimulation (anodic current, 100 µA/30 sec) of thalamic nuclei was studied in nonanesthetized freely-behaving rats bearing chronic implanted electrodes and plastic cannulae inserted into the jugular vein for blood sampling. Stimulation of the anterior thalamic nuclei, the nucleus (n.) mediodorsalis thalami (MD) and the n. posteromedianus thalami at 2 p.m. on the day of proestrus prevented spontaneous ovulation and the release of LH which takes place on that day. No effect on ovulation or LH release was observed after stimulation of the n. lateralis thalami, the n. ventralis thalami or other thalamic nuclei or after passing a cathodic current through the n. MD. Stimulation of the n. MD resulted also in a significant decrease of the elevated serum LH levels found after an injection of progesterone into ovariectomized estrogen-primed rats. These results indicate that nuclei of the medial thalamic region are capable of inhibiting LH secretion. No stimulatory influence on LH release was observed after thalamic stimulation in ovariectomized estrogen-treated rats

ISSN:0028-3835    

DOI:10.1159/000122609

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Experiments performed on unanesthetized ovariectomized female rabbits demonstrated the effects of estradiol benzoate (EB; 20 µg i.v.) on the electrical activity of hypothalamic units which send their axons to the median eminence. Of a total of 1,840 cells recorded in hypothalamic and preoptic areas, 46 (2.5%) were antidromically activated by stimulating the median eminence. Under the present experimental conditions, EB induced a progressive diminution in the mean firing rate of these cells observed throughout the recording period (30–120 min). In addition to cells projecting to the median eminence, neurons which could not be antidromically invaded using our techniques were observed to be sensitive to estrogen. Estrogen administration produced a long-lasting inhibition of antidromically activated cells and a depression of much shorter duration (15–20 min) of unidentified nonstimulated units. These data suggest the existence of two types of hypothalamic neurons sensitive to estr

ISSN:0028-3835    

DOI:10.1159/000122610

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Hypothalamic corticotropin-releasing factor (CRF) activity was only slightly increased by 1 min ether stress and was unaltered by 2.5–10 min ether stress, 15-day adrenalectomy, 11-day hypophysectomy or 3-day dexamethasone treatment. There was a slight tendency for the hypothalamic CRF activity to be higher in the p.m. than in the a.m. Basal hypothalamic deafferentation did not significantly affect hypothalamic CRF content in the a.m. or p.m. compared to intact controls. We conclude that hypothalamic CRF content maintains relative constancy under conditions of marked acute or chronic stimulation or suppression of ACTH secretio

ISSN:0028-3835    

DOI:10.1159/000122611

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Amphetamine, a clinically used sympathomimetic central-acting drug, was administered in Spansule capsules in a blind schedule to 8 normal obese volunteers in a daily (8 a.m.) single 15 mg dose for 7 days. The study, conducted in the metabolic ward, included two 7 day placebo periods (pre- and post-drug). During the 1st placebo period, all subjects exhibited within the 1st 2 h of sleep a clear and significant nocturnal increase of growth hormone (GH) closely related with sleep stages 3 and 4. Thyrotropin (TSH) increase was observed between 01.00 to 04.00 h and was accompanied by a reduction of thyroxine (T4) levels. Cortisol levels presented their characteristic rhythm, clearly associated with paradoxical sleep (REM). Amphetamine significantly reduced stages 3 and 4, as well as REM sleep, and increased stage 2. GH and cortisol circadian profiles were preserved, although their magnitude was diminished. The extent of nocturnal TSH and T4 changes was significantly reduced. Drug withdrawal was accompanied by a rebound of REM sleep and a trend to recover the pretreatment TSH and T4 temporal profile. These results suggest that adrenergic neurotransmitters may be a significant modulating system for TSH and cortisol, whereas GH nocturnal secretion may be influenced by different mechanisms.

ISSN:0028-3835    

DOI:10.1159/000122612

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Experiments were performed on male Holtzman albino rats. Stainless steel semimicroelectrodes 60 µ in diameter were implanted stereotaxically in the ventromedial hypothalamus (VMH) and in the pineal body (PB). Six to eight days following this operation, the sensory field potentials from freely behaving, unrestrained rats were averaged. After a control recording was achieved, animals were given injections i.p. with 10, 30 or 50 mg/kg of morphine and recordings were resumed for 45 min. Naloxone was then administered and recordings were monitored during another 45 min period. Three consistent components of the averaged sensory evoked potentials were evaluated. In both structures following the two lower doses of morphine (10 and 30 mg/kg), increased and decreased response amplitudes were observed, while following 50 mg/kg morphine, mainly increased response amplitudes were obtained in both structures. With increased doses, the percentage of responses was increased. During the 45 min of recording after morphine, effects remained consistent. Differences in the percentage and the direction of the responses were observed between the VMH and the PB. Naloxone (1 mg/kg) reversed the morphine effect in the two structures, both the increased and decreased responses. The possible interactions between morphine and endocrine function of the two structures are discussed

ISSN:0028-3835    

DOI:10.1159/000122613

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

In four-day cycling rats studied during the estrous cycle, the levels of circulating norepinephrine (NE) showed a sharp rise concomitant with the LH surge in the afternoon of proestrus. Following the peak, plasma NE fell rapidly to the minimum value by the morning of estrus. The administration of progesterone to ovariectomized estrogen-primed rats resulted in a surge in plasma NE levels 4 h after progesterone treatment. The maximal levels attained were 3-fold greater than baseline values, falling rapidly to reach basal values 8 h after the administration of progesterone. The amine levels remained unaffected 12–20 h later. The LH values attained a maximum 8 h after the injection of progesterone. In rats treated with estradiol benzoate (EB) followed by 0.1 ml of oil instead of progesterone, neither the NE nor the LH peak were observed. These findings are discussed with respect to the significance of increased amounts of plasma NE related to the LH surg

ISSN:0028-3835    

DOI:10.1159/000122614

出版商:S. Karger AG    

年代:1976

数据来源: Karger