摘要:

Systolic blood pressure (SBP), diastolic blood pressure (DBP), norepinephrine (NE), cortisol (CRT), growth hormone (GH), and prolactin (PRL) plasma levels were investigated in 46 normal subjects, 28 high intestinal tone (high IT) and 18 low intestinal tone (low IT), before and after the administration of a single intramuscular dose of clonidine (2.5 µg/kg). High IT subjects had lower mean values of DBP than low IT subjects, and basal NE was significantly greater in low IT than in high IT subjects. A negative correlation between NE and IT values was found for the high IT, but not for the low IT group, during the preclonidine periods. The drug reduced SBP in high IT, whereas it reduced SBP plus DBP and NE in low IT subjects. Clonidine induced significant reductions of CRT and increases of GH in both groups; furthermore, a slight but significant reduction of PRL was registered in high IT group. The drug also induced increase of distal colon tone in high IT subjects and suppressed phasic activity (waves) in low IT subjects. While a significant positive correlation was found between NE and DBP in low IT subjects during postclonidine periods, no correlation was found between the two parameters in high IT subjects. Other significant positive (+) and negative (–) correlations during postclonidine periods were: CRT/GH (–), CRT/PRL (+), and GH/PRL (–) in high IT subjects; NE/CRT (+), NE/GH (–), CRT/GH (–), CRT/DBP (+), and GH/DBP (-) in low IT subjects. Finally, significant negative correlation was found between NE and distal colon tone during postclonidine periods in high IT subjects. Our results suggest that there is a sympathetic (NE) hypoactivity in high IT subjects and a sympathetic (NE) hyperactivity in low IT subjects. Postsynaptic and presynaptic pharmacological mechanisms are postulated in order to explain these two different patterns of responses to the challenge of

ISSN:0028-3835    

DOI:10.1159/000124082

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Target neurons for 3H-corticosterone were identified by autoradiography and tyrosine hydroxylase containing neurons were identified by immunocytochemistry in the same sections of lower brain stem of 38-day-old rats, 10-day-old rats and adult mice. In all animals studied, the same topographic distribution of neurons was found which exibited a nuclear accumulation of 3H-corticosterone. Target neurons for 3H-corticosterone were widely distributed in the brain stem. Motor neurons of the cranial nerves and certain neurons of the reticular formation were among the most heavily labeled cells. Neurons containing immunoreactive tyrosine hydroxylase were detected in all of the classical noradrenergic and adrenergic cell groups. Tyrosine hydroxylase containing neurons did not concentrate radioactivity, but were found in close proximity to neurons which concentrated the radiolabeled glucocorticosteroid, especially in the ventrolateral medulla (area Ai) and in the ventrolateral pons (area A5). These results do not support, but do not exclude, a direct genomic action of corticosterone on catecholamine neurons in the lower brain stem.

ISSN:0028-3835    

DOI:10.1159/000124083

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Exogenous arachidonic acid (AA) incubated in presence of male rat hypothalamus, shows a low rate of conversion (<1%) of the substrate with a major product, identified as 12-hydroxyeicosatetraenoic acid (12-HETE) by reverse phase-high performance liquid chromatography (rpHPLC) and gas chromatography-mass spectrometry (GC-MS). Furthermore, immunoreactive 12-HETE estimated after purification on rpHPLC is produced by hypothalamus slices or median eminences (MEs) incubated in absence of any exogenous precursor. The effect of 12-HETE was tested on the release of LHRH from rat MEs after a 30-min incubation and was compared to the effect of another lipoxygenase product, 5-HETE, and to the well-known stimulatory effect of prostaglandin E2 (PGE2). The three AA metabolites stimulate LHRH release. A significant stimulatory effect on LHRH release is obtained with 10–9 M of 12-HETE and only with 10–8 M of 5-HETE or PGE2. Furthermore, the effect of higher concentrations is different according to the eicosanoid tested. The maximal response (176% of the control) is reached with 12-HETE at 10-8 M No significant change is observed at 10–7 and 10–6 M The response with 5-HETE is also maximal (162% of the control) at 10–8 M but decreases significantly (only 117% of the control) at 10"6 M The amplitude of the response to PGE2 is larger and higher, reaching a plateau (300% of the control) at 10–6 M 12-HETE has no effect on somatostatin (SRIF) release, as already known for PGE2. These results are the first evidence of selective effect of lipoxygenase products on the release of neuropeptides from rat hypothalamus. The identification of 12-HETE as endogenous metabolite is in favor of a physiological role of t

ISSN:0028-3835    

DOI:10.1159/000124084

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Peptides of cardiac origin, termed atrial natriuretic factors, possess both natriuretic and diuretic properties, actions which physiologically contradict those of the antidiuretic peptide, arginine vasopressin (AVP). In addition to their opposing actions in the kidney, the present results indicate that one of these factors, Atriopeptin III, can inhibit dehydration and hemorrhage-induced AVP release in the rat. 3 days of water deprivation resulted in elevated plasma AVP levels (36.1 ± 4.7 pg AVP/ml) which were significantly reduced following intravenous infusion of 0.02 (21.4 + 3.6), 0.2 (15.6 ± 1.6), and 2.0 (13.9 ± 3.8) nmol Atriopeptin III. Furthermore, 2.0 nmol Atriopeptin III significantly reduced post-hemorrhage levels (54.8 ± 13.7) of AVP to values that approximated resting levels (10.2 ± 3.7). The results suggest a role for cardiac peptides in the control of AVP release as well as the existence of a counterregulatory system, peptidergic in nature, for the maintenance of fluid and electrolyte homeost

ISSN:0028-3835    

DOI:10.1159/000124085

出版商:S. Karger AG    

年代:1985

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000124086

出版商:S. Karger AG    

年代:1985

数据来源: Karger