摘要:

Ovariectomized (Ovx) rats were treated (s.c.) with estradiol benzoate (E2B) for 7 days, and then 10, 25 or 100 ng LH-RH were microinjected into the 3rd ventricle. Intraventricular LH-RH elevated plasma LH at 10 and 30 min in a dose-response manner. In experiment 2, Ovx rats were treated with E2B or oil for 7 days and then intraventricularly injected with 25 ng LH-RH. Two days later, 100 ng LH-RH were systemically administered. E2B treatment resulted in a greater release of LH in response to the intraventricular administration of LH-RH but not to the systemic injection. A direct measure of median eminence (ME) uptake of LH-RH was used in experiment 3. Ovx-E2B or oil-treated rats were decapitated 10 min after intraventricular injection of 125I-LH-RH, 125I or 3H-glycine. The ME region of the hypothalamus, cortex, anterior pituitary (AP) and plasma were solubilized and their radioactivity determined. E2B increased the radioactivity in the ME following injection of 125I-LH-RH but not in other tissues. Tissue uptake of 125I and 3H-glycine were similar in E2B or oil-treated rats. These data indicate E2B facilitates the incorporation of LH-RH into the ME from the cerebrospinal fluid (CSF).

ISSN:0028-3835    

DOI:10.1159/000122795

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The possible existence of extrapituitary melanocyte stimulating hormone (MSH) in various regions of the rat brain has been studied in intact and hypophysectomized rats. Using a sensitive and specific radioimmunoassay (RIA), αMSH has been found in a number of brain regions in intact rats. The standard curves of synthetic αMSH and the dilution curves for pars intermedia nervosa (PIN), pars distalis (PD), hypothalamus and thalamus extracts were strictly parallel. The αMSH concentrations were measured in PIN (6,225 ± 962 ng/mg wet tissue); PD (12.5 ± 1.41 ng/mg); pineal (380 ± 29 ng/g wet tissue); hypothalamus (645 ± 161 ng/g) and thalamus (33.3 ± 5.26 ng/g). In rats hypophysectomized for 1 or 2 months, the highest concentrations of immunoreactive αMSH were found in pineal (353 ± 140 ng/g wet tissue), hypothalamus (85.8 ±14.1 ng/g) and thalamus (39.8 ± 13.9 ng/g). Hypophysectomy significantly reduced hypothalamic MSH content and concentration but did not alter MSH concentration in pineal and thalamus. From these results, we conclude that hypothalamic αMSH is, in part, of hypophyseal origin while pineal and thalamus «MSH does not originate from the pituitary. After Sephadex G-25 gel filtration, synthetic αMSH and PIN extracts showed a single peak of both bioactive and immunoreactive αMSH. In the same conditions, extracts from the 5 brain regions studied in hypophysectomized rats chromatographed as a single peak of immunoreactive MSH but as 2 peaks of apparent bioactive MSH, 1 concident with synthetic αMSH and the other far after the salt volume. We conclude that αMSH is found in a number of brain areas and its presence after hypophysectomy would indicate synthesis within the centr

ISSN:0028-3835    

DOI:10.1159/000122796

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Serotonin (5-HT) and its major metabolite, 5-hydroxyindole acetic acid (5-HIAA), were assayed in hypothalamus, hippocampus, and cortex during selected stages of pregnancy and lactation in the rat. No changes in 5-HT were observed in any of the brain areas analyzed. However, concentrations of 5-HIAA in hypothalamus and hippocampus, though not in cortex, showed marked changes during the immediate postpartum period. The significance of these changes is discussed in terms of possible hormone-neurotransmitter relationships.

ISSN:0028-3835    

DOI:10.1159/000122797

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

In the unanesthetized, ovariectomized rhesus monkey, gonadotropin secretion is episodic while prolactin (Prl) release is relatively constant. Under pentobarbital anesthesia, however, Prl secretion also becomes pulsatile in synchrony with the discharges of LH. This finding suggests that the anesthesia has unmasked normally inhibited Prl releasing stimuli which are driven by the circhoral ‘clock’ that also times the discharges of G

ISSN:0028-3835    

DOI:10.1159/000122798

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Adrenocortical response to exogenous acetylcholine (Ach) was investigated, under anesthetized conditions, in intact, hypophysetomized and head X-irradiated dogs. Intravenous injection of Ach (1 mg/kg b.w.) to intact dogs resulted in marked increases in the secretion of 17-hydroxycorticosteroids (17-OHCS) by the adrenal gland. The maximum response was seen at 10 min after the injection and a return to preinjection levels tended to occur by 60 min. This effect was abolished completely by hypophysectomy. In dogs whose heads had been irradiated with 200 and 1,000 R of X-rays 1 day previously, a considerably lower response to Ach was found; 17-OHCS output at the time when the secretion had been maximum was 44-53% less than that in non-irradiated dogs.

ISSN:0028-3835    

DOI:10.1159/000122799

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Evolution of the (arginine)-vasopressin (AVP) content of the supraoptic (SON), paraventricular (PVN) and suprachiasmatic nuclei (SchN) and of the posterior lobe of the hypophysis (PLH) has been studied in rats at successive stages of rehydration after 4 days deprivation of drinking water. Particular attention has been focussed on short periods of rehydration. Evolution of the AVP content of the hypothalamo-posthypophysial system (HHS), the blood serum AVP concentration and osmolalities of serum and urine were compared. Variations of the AVP content in the different hypothalamo-hypophysial structures are parallel. A marked depletion of AVP is observed after 2 and 4 days of dehydration. The AVP content of the PLH and of the hypothalamic nuclei shows two dramatic and short increases 15 min and 3 h after the onset of rehydration; these results are discussed in relation to the known physiological regulation mechanism of the HHS. In the PLH depleted by dehydration, reloading with neurosecretory granules (NSG) begins to be noticeable only after 24 h of rehydration, so that it does not seem to account for elevations of the AVP content occurring earlier. These could be related to a marked increase of the smooth endoplasmic reticulum (SER) network taking place in axons and nerve endings before the NSG reloading.

ISSN:0028-3835    

DOI:10.1159/000122800

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The effect of L-norepinephrine (NE) on renin release by slices of kidney cortex from sodium-replete and sodium-deficient rats was studied in vitro. The rate of renin release by slices from sodium-deficient rats in the absence of added NE increased in proportion to the length of dietary sodium restriction and was significantly greater at all times than release by slices from sodium-replete animals. NE added to slices from the sodium-replete animals in concentrations ranging from 2 × 10–9 to 2 × 10–4 M caused a significant renin release only at a concentration of 2 × 10–7M. In contrast, the rate of renin release by slices from the sodium-deficient rats increased in a dose-related fashion when the NE concentration ranged from 2 × 10–12 to 2 × 10–7 M. NE in a concentration of 2 ×10–5 had a lesser stimulatory effect, and 2 ×10–4 M caused a significant inhibition of renin release. This inhibition was converted to stimulation by addition of the α-adrenergic blocking drug phentolamine. Phentolamine by itself was ineffective. The increases and decreases in renin release produced by NE were, in general, accompanied by increases and decreases in the cyclic AMP content of the slices. The changes in renin release were linear for 60 min, but the changes in cyclic AMP content were greater at 5 and 20 min than at 60 min. A dose-response relationship between the changes in renin release and cyclic AMP content was not observed. These data indicate that sodium deprivation enhances the sensitivity of the renin-secreting cells to catecholamine stimulation, and are consistent with the hypothesis that the increase in renin secretion produced by NE is mediated via cyclic AMP. The data also indicated that in high concentrations, NE exerts an inhibitory effect on renin release, and that this effect is mediated via stimulation of α

ISSN:0028-3835    

DOI:10.1159/000122832

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

In order to elucidate neural pathways concerned with the proestrous surge of LH, FSH and prolactin (Prl) release, brain transection or lesion was made acutely under ether anesthesia between 12.00 and 14.00 h of proestrus, and electrochemical stimulation was done under anesthesia with pentobarbital sodium (31.5 mg/kg b.w.) injected at 13.45 h. Transection which interrupted the connection of septum (SEPT), diagonal band of Broca (DBB) and bed nucleus of stria terminalis (BST) with the preoptic-suprachiasmatic area interfered with ovulation and surge of release of all 3 hormones. Isolation of the basal part of the suprachiasmatic area, including the suprachiasmatic nucleus (SCH), blocked ovulation also. Bilateral lesions in the medial preoptic area (MPO) with platinium-iridium electrode blocked ovulation and the surge of LH and Prl release, but not of FSH. Lesions in the SCH blocked ovulation and the surge of LH, but not of FSH and Prl. In the rat with acute isolation of the basal part of the suprachiasmatic area and SCH, stimulation of the MPO failed to induce ovulation and LH release, but was followed by FSH release. Prl release was not inhibited as in the intact rat. When the rat had the antero-SCH cut, stimulation of the SCH induced LH release but not FSH, and the inhibition on Prl release was pronounced. These findings offer evidence that the limbic-forebrain inputs are necessary for the preoptic integration in order to stimulate the proestrous surge of LH, FSH and Prl release. Furthermore, it is possible that separate pathways from the preoptic area to the medial basal hypothalamus are concerned in the stimulation of individual hormones -a restricted route for LH which may pass through the SCH, a diffuse one for FSH which may pass through either the SCH or anterior hypothalamic area, and a relatively diffuse one for Prl which may pass outside the SCH.

ISSN:0028-3835    

DOI:10.1159/000122801

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

We have reported that both an extract of rat hypothalamus-stalk-median eminence (HE) and 5-hydroxytryptamine (5-HT) will stimulate the release of ACTH biological activity from acutely, non-enzymically dispersed rat pars intermedia (PI) cells. We have also found that the ACTH activity within the PI cells is composed of 4 chromatographically separable entities, but only a small proportion of the total ACTH activity co-elutes with ACTH1-39. In the present study we subjected the media, after incubation of PI cells with either HE or 5-HT, to sequential chromatography on Sephadex G-50 F and G-100 SF. We found the same 4 ACTH-like moieties as in the PI cell extracts. Only the release of the 2 earliest eluting components, presumably of much larger molecular dimensions than ACTH1-39, was enhanced by either HE or 5-HT. There was no augmented release of the ACTH component having molecular dimensions similar to ACTH1"39. Thus, in our in vitro system, the ACTH biological activity released from PI cells is not the size of ACTH1-39, but is composed of at least 2 much larger molecules which possess ACTH (as well as some MSH) biological activity.

ISSN:0028-3835    

DOI:10.1159/000122833

出版商:S. Karger AG    

年代:1978

数据来源: Karger