摘要:

Septal influences on resting adrenocortical activity were tested in the pigeon by electrical stimulation or electrolytic lesions located in either the medial or the lateral septum. Stimulation of the medial septal area in unanesthetized unrestrained pigeons with chronic implants led to a marked decrease in plasma corticosterone. Stimulation of the lateral septal area was not effective in promoting any corticosterone variation. Lesion placement in the nucleus septalis lateralis resulted in a moderate increase in basal corticosteronemia. The elevation in circulating corticosterone was much higher after destruction of the n. septalis medialis and high values were found at every time during the day. Suppression of the diurnal variation in plasma corticosterone with such a high stable level was compared to previous data which were obtained in pigeons after hippocampectomy and after partial anterior or complete deafferentation of the hypothalamus.

ISSN:0028-3835    

DOI:10.1159/000122409

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

A fluorescent antibody study of LRF-producing neurons was made with antisera to synthetic LRF in normal male and female cats and dogs. Specific immunoreactive perikarya have been found in the rostral hypothalamus of both species. In the dog, specific immunoreactive perikarya have also been found in the pars oral¡s tuberi, the infundibular nucleus, the premammillary region, and even the dorsomedial and ventromedial areas and the rostral mesencephalon

ISSN:0028-3835    

DOI:10.1159/000122410

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The binding characteristics of glucocorticoids to cytoplasmic and nuclear fractions of the adenohypophysis were determined and an attempt was made to correlate steroid uptake with physiological action. Binding was of high affinity and exhibited a limited number of acceptor sites for dexamethasone (Dx). It was shown that the steroid-receptor complex dissociated rapidly at 37 °C, but was stable at low temperatures. An inverse relationship was detected between the plasma corticosterone (B) titer and the capacity of receptors to combine 3H-Dx. Shortly after stress or injection of physiological doses of B, 50 to 70% of the acceptor sites were saturated. Progressive desaturation of the occupied receptors appeared to depend upon time and the plasma B concentration. Some evidence was also provided supporting a possible correlation between the extent of Dx inhibition of in vitro ACTH secretion and the degree of binding sites’ occupancy. These results suggest that glucocorticoid binding to pituitary receptors may be correlated with the physiological action of the steroids on ACTH relea

ISSN:0028-3835    

DOI:10.1159/000122411

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Using borate buffer a substance that suppresses the ovulation induced with PMS and HCG in immature mice was obtained from acetone-defatted bovine pineal powder by an extraction method similar to that used for an extraction of a gonadotropin-inhibiting substance in urine. This gonadotropin inhibitor in the pineal powder differs from melatonin or arginine vasotocin and seems to be different from the water soluble antigonadotropic substance which has been isolated from the bovine and ovine pineal. Partial purification of the gonadotropin inhibitor was accomplished by a Sephadex G-100 column.

ISSN:0028-3835    

DOI:10.1159/000122412

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The possible participation of cholinergic mechanisms in the control of LH and LH-RH secretion has been studied using an in vitro procedure. Halved anterior pituitaries (AP) of normal adult male rats were incubated for 6 h either alone or in the presence of hypothalamic fragments (HF). At the end of the incubation period, LH was evaluated in the media using a biological assay. AP halves, when incubated alone, released small amounts of LH. The addition of HF to the media containing AP tissue did not change LH release. Acetylcholine (Ach) added to the incubation flasks containing only AP tissue did not increase LH output over the output of AP incubated without Ach. On the contrary, Ach significantly enhanced LH release when added to the incubation media of flasks simultaneously containing AP tissue and HF. Atropine had no effect on the release of LH from AP incubated alone. However the addition of atropine to the incubation media containing the halved AP, HF and Ach totally prevented the effects of Ach on LH release. Prostigmine enhanced the release of LH in the media containing AP plus HF. The LH-releasing effect of Ach in the AP plus HF coincubates was not influenced by the α-adrenergic blocking agent, phentolamine. These data indicate: (1) that from HFs incubated in vitro, Ach is able to release a factor (most probably LH-RH) which increases the secretion of LH from AP tissue; (2) that this effect of Ach follows the general rules of cholinergic systems (blockade by atropine, potentiation by prostigmine, etc.); and (3) that the LH-RH releasing activity of Ach is not linked to the liberation of catecholamines (dopamine, norepinephrine, etc.). These results suggest that cholinergic mechanisms play a role in the control of LH-RH release

ISSN:0028-3835    

DOI:10.1159/000122413

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Ovariectomized rats were injected with estradiol benzoate (EB) on day 1. The rats received propylene glycol alone (control) or with Actinomycin-D (Act-D) at 08.00 h, followed by EB at 12.00 h on day 3. Plasma LH levels were markedly elevated at 18.00 h on days 3 and 4 in control rats; Act-D treatment failed to modify the surge of LH on day 3, but abolished it on day 4. The site of Act-D’s blockade of estrogen-induced LH release was investigated. Act-D treatment suppressed serum levels of LRF while it failed to modify either hypothalamic LRF content or noon levels of pituitary and serum LH on day 4. Act-D treatment consistently reduced the weight and the ribonucleic acid (RNA) content of the pituitary; a similar effect on RNA in the medial basal hypothalamus was not detected on day 4. On the other hand, electrochemical stimulation of the medial preoptic area of Act-D-treated rats on day 4 raised plasma LH significantly. However, the elevations at 45 min after stimulation were less in Act-D-treated than in control rats. Similarly, a significantly smaller response of LH release was observed at 15 min following intravenous injections of LRF in Act-D rats than in controls. These studies suggest that Act-D-sensitive steps exist at more than one site on the preopticotuberal pituitary axis involved in the stimulatory feedback action of estrogen on LH releas

ISSN:0028-3835    

DOI:10.1159/000122414

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

To determine whether brain monoaminergic neurons are involved in the release of gonadotropins responsible for estrogen increases before proestrus, various inhibitors and precursors of monoamine biosynthesis were administered subcutaneously or intracranially to the 3rd ventricle at 10.00 or 20.00 on the day before proestrus, the 2nd day of diestrus (DII) in 4-day cycling rats. The inhibitors used were α-methyl-p-tyrosine (α-MPT) and bis-(4-methyl-1-homopiperazinyl-thiocarbonyl)-disulfide (FLA-63). The effects of these drugs on changes in vaginal cytology, ovulation, uterine weight, weight of uterine intraluminal fluid, and on serum concentrations of LH and FSH were evaluated in selected experiments. (1) Administration of α-MPT (150 mg/kg s.c), an inhibitor of tyrosine hydroxylase, at 10.00 on DII reduced weights of uterus and intraluminal fluid on the day of expected proestrus (P), prevented vaginal cornification on estrus (E), blocked ovulation in all 10 rats, and induced prolonged diestrus. (2) Administration of FLA-63 (10 mg/kg s.c), an inhibitor of dopamine-β-hydroxylase, at 10.00 on DII reduced weights of uterus and intraluminal fluid on P, blocked ovulation for a few days but did not prevent vaginal cornification at the expected time of E. (3) Administration of α-MPT (200 mg/kg) or FLA-63 (15 mg/kg) at 20.00 on DII blocked ovulation in all of 8 and 7 rats, respectively, but these treatments did not block vaginal cornification at the expected time in any animal. (4) Administration of L-DOPA (100 mg/kg) or dihydroxy-phenylserine (DOPS, 200 mg/kg) with α-MPT (200 mg/kg) at 20.00 on DII reversed the blocking effect of α-MPT on ovulation in 3 out of 6 and 3 out of 5 rats, respectively. (5) Direct application of crystalline α-MPT or FLA-63 (about 3–5 µg) to the 3rd ventricle at 20.00 on DII also blocked ovulation in all of 7 and 5 rats, respectively. (6) Both systemic and intraventricular

ISSN:0028-3835    

DOI:10.1159/000122415

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Previous experiments from this laboratory using the hypothalamic island have demonstrated that the adrenocortical discharge following sciatic nerve stimulation is mediated by neural pathways only. With the purpose of identifying the neural structures involved, this response was studied in rats with bilateral lesions in the medial forebrain bundle (MFB), mammillary peduncle (MP), fasciculus longitudinalis dorsalis (FLD), mid-brain reticular formation (MRF) and the medial geniculate body (GM). Lesions in the MFB, MP and MRF have inhibited the adrenocortical response following sciatic nerve stimulation. These and other data indicate that the above structures are involved in the mediation of this response and that the afferent pathway enters the mediobasal hypothalamus anteriorly.

ISSN:0028-3835    

DOI:10.1159/000122416

出版商:S. Karger AG    

年代:1975

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122417

出版商:S. Karger AG    

年代:1975

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122418

出版商:S. Karger AG    

年代:1975

数据来源: Karger