Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.15 (renin)
 35,795 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sympathetic nervous system and the renin-angiotensin mechanism each can influence blood pressure separately but the two systems also interact functionally in various ways. There is good evidence that central catecholaminergic neurons play an essential role in the regulation of blood pressure but it may be assumed that other putative neurotransmittors such as serotonin, GABA and various peptides also participate in the central regulation of blood pressure. The secretion of renin, which catalyzes the production of angiotensin(s), is stimulated by increased sympathetic activity and circulating sympathetic amines. Dopamine seems to have an opposite effect on renin release but it is not clear whether this is due to a direct effect on the renin producing cells or an influence on sympathetic activity, centrally or peripherally.
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PMID:Sympathetic amines, renin and blood pressure. 2 52

The influence of GABA and of drugs, known to alter GABA-metabolism, on the hypovolaemia-provoked vasopressin release was investigated in rats. Blood volume was decreased without altering plasma osmolality or arterial blood pressure by i.p. injection of polyethylene glycol and the resulting plasma vasopressin concentration was measured using a radioimmunoassay. I.c.v. injections of GABA (0.4-2 mg) markedly suppressed the hypovolaemia-induced vasopressin release. The central inhibitory effect of GABA could not be related to appropriate changes in peripheral parameters believed to regulate vasopressin release (arterial blood pressure, renin-angiotensin system). Aminooxyacetic acid (9-81 mg kg-1, i.m.) and gamma-vinyl-GABA (1.5 g kg-1, i.p.), two potent inhibitors of GABA aminotransferase and known to increase brain GABA content, reduced vasopressin release to a comparable degree as did GABA (i.c.v.). On the other hand, 3-mercaptopropionic acid (10-90 mg kg-1, i.p.), an inhibitor of the GABA synthetizing enzyme glutamic acid decarboxylase, promoted the release of vasopressin when the rats were killed prior to the onset of convulsions. These results, on the whole, intimate the existence of a GABA-mediated inhibition in the central control of vasopressin release.
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PMID:Evidence for the involvement of a GABA-mediated inhibition in the hypovolaemia-induced vasopressin release. 719 56

The brain GABAergic system was previously shown to influence blood pressure (BP) maintenance in rats which may in part be accomplished by disruption of the central renin-angiotensin system (RAS). We examined the potential role of GABA in sustaining the high BP exhibited by the spontaneously hypertensive rat (SHR) model of human essential hypertension. Intracerebroventricular (i.c.v.) infusion of GABA produced decreases in BP in members of three rat strains, including Wistar-Kyoto (WKY) and Sprague-Dawley normotensive controls and SHR. The SHR were significantly more sensitive to GABA than the normotensive strains. Next, the GABA receptor antagonist bicuculline (BMI) was infused i.c.v. and produced increases in BP in members of each strain. Finally, i.c.v. pretreatment with the specific angiotensin receptor antagonist [Sar1, Thr8]AII (sarthran), blocked subsequent GABA-induced decreases in BP in members of all three strains, and there was a trend toward sarthran attenuation of BMI-induced increases in BP. These results encourage the hypothesis that the hypotensive effects produced by central application of GABA are mediated by the brain angiotensin system.
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PMID:GABA and bicuculline-induced blood pressure changes in spontaneously hypertensive rats. 767 72

Changes in the blood hormonal levels were studied in 36 rabbits with electrodes implanted to the area of the dorsomedial nuclei of the hypothalamus in the course of a 5-cycle electrostimulation experiment. After each period blood hormonal levels were correlated to the activities of the hypothalamic catecholamine-, GABA-, and serotoninergic systems. The first two cycles of the experiment were associated with a high activity of the hypothalamic mediator systems and with increased levels of all hormones in the blood. The functional activity of the hypothalamus was reduced due to the predominance of stress-limiting systems. The initial reduction of GABA, and then of serotonin in the hypothalamus caused be the end of experiment a reduction of the blood levels of the tested hormones, except the Ca-regulating ones and active renin. Disturbances in the regulatory mechanisms of hypothalamic mediator systems leads to an increase in its excitability and to transformation of the adaptive pattern of hormonal changes into pathological mechanisms of prolonged emotional stress.
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PMID:[Effects of hypothalamic mediator systems on the hormonal changes in rabbit blood during prolonged electric stimulation of emotiogenic zones of the hypothalamus]. 774 41

Since the adrenal cortex and medulla are intimately interrelated, the effects of anticonvulsant drugs may affect both of these hormonal systems. Anticonvulsants are commonly used long-term for the treatment of epilepsy, chronic pain syndromes and affective disorders. In patients where adrenal function needs to be evaluated, the clinician should be aware of the potential interactions between anticonvulsant medication and the hypothalamo-pituitary-adrenal axis. Carbamazepine, phenytoin and phenobarbitone induce the liver P450 cytochrome enzyme system and stimulate steroid clearance. Therefore, patients investigated for Cushing's syndrome may show a falsely positive dexamethasone suppression test, and patients with adrenal insufficiency on steroid replacement may require increased doses of steroids; furthermore, increased corticosteroid-binding-globulin levels are also associated with chronic anticonvulsant administration. In addition, concomitant treatment with benzodiazepines, probably acting via the GABA pathway, can also alter the ACTH/cortisol response to stressful stimuli. Direct and indirect evidence suggest that benzodiazepines, acetazolamide and magnesium sulphate can also interfere with the renin-angiotensin-aldosterone system. Finally, to our knowledge, no systemic data are yet available in the human on the effect of antiepileptics on the function of the adrenal medulla and/or catecholamine metabolism; however, as the adrenal medulla receives part of its blood supply from the cortex, it is possible that alterations of cortical hormonal composition might affect adrenal medulla function overall.
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PMID:The effects of anti-convulsant drugs on adrenal function. 969 68

We examined the role of the central nervous system, and particularly the renin-angiotensin (RA) system, in the development of hypertension produced by chronic inhibition of NO synthesis. In experiment 1, Wistar rats drank either nitro-L-arginine-methyl ester (L-NAME) or tap water. Before L-NAME treatment rats were divided into 6 groups. Four of them were administered either losartan or artificial cerebroventricular fluid (a-CSF) intracerebroventricularly (i.c.v.) for 1 week using an osmotic mini pump. The other two groups were administered the same amount of losartan intravenously (i.v.). In experiment 2, cardiovascular responses to acute i.c.v. losartan and muscimol, a GABA(A) agonist, were examined in conscious L-NAME-treated rats. Finally, in experiment 3, effects of ablation of the AV3V (anteroventral third ventricle) area, known to be one of the centers of cardiovascular control, were tested in the development of L-NAME hypertension. The development of hypertension by L-NAME treatment was attenuated with chronic i.c.v. losartan in a dose-dependent manner, while i.v. losartan had no effect. One week after cessation of i.c.v. losartan, blood pressure was elevated to the same level as in a-CSF-infused, L-NAME-treated rats. Acute i.c.v. losartan produced no cardiovascular changes in either L-NAME-treated or control rats. On the other hand, although i.c.v. muscimol elicited depressor effects in both groups, these responses were significantly larger in L-NAME-treated rats. Cardiovascular responses to i.v. hexamethonium were similar in both groups. The existence of prior lesions in the AV3V area significantly attenuated the development of L-NAME-induced hypertension. These results indicate that the central RA system plays an important role in the development of hypertension produced by chronic inhibition of NO synthase. Moreover, disorder of the central GABA system, rather than that of the RA system, might be important in the maintenance of hypertension in this model.
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PMID:Role of the central nervous system in the development of hypertension produced by chronic nitric oxide blockade in rats. 1121 29

The process of normal aging is accompanied by changes in sleep-related endocrine activity. During aging, an increase in cortisol at its nadir and a decrease in renin and aldosterone concentration occur. In aged subjects, more time is spent awake and slow-wave sleep is reduced: there is a loss of sleep spindles and accordingly a loss of power in the sigma frequency range. Previous studies could show a close association between sleep architecture, especially slow-wave sleep, and activity in the glutamatergic and GABAergic system. Furthermore, recent studies could show that the natural N-methyl-D-aspartate (NMDA) antagonist and GABA(A) agonist Mg(2+) seems to play a key role in the regulation of sleep and endocrine systems such as the HPA system and renin-angiotensin-aldosterone system (RAAS). Therefore, we examined the effect of Mg(2+) in 12 elderly subjects (age range 60-80 years) on the sleep electroencephalogram (EEG) and nocturnal hormone secretion. A placebo-controlled, randomised cross-over design with two treatment intervals of 20 days duration separated by 2 weeks washout was used. Mg(2+) was administered as effervescent tablets in a creeping dose of 10 mmol and 20 mmol each for 3 days followed by 30 mmol for 14 days. At the end of each interval, a sleep EEG was recorded from 11 p.m. to 7 a.m. after one accommodation night. Blood samples were taken every 30 min between 8 p.m. and 10 p.m. and every 20 min between 10 p.m. and 7 a.m. to estimate ACTH, cortisol, renin and aldosterone plasma concentrations, and every hour for arginine-vasopressin (AVP) and angiotensin 11 (ATII) plasma concentrations. Mg(2+) led to a significant increase in slow wave sleep (16.5 +/- 20.4 min vs. 10.1 +/- 15.4 min, < or =0.05), delta power (47128.7 microV(2) +21417.7 microV(2) vs. 37862.1 microV(2) +/- 23241.7 microV(2), p < or =0.05) and sigma power (1923.0 microV(2) + 1111.3 microV(2) vs. 1541.0 microV(2) + 1134.5 microV(2), p< or =0.05 ). Renin increased (3.7 +/- 2.3 ng/ml x min vs. 2.3 +/- 1.0 ng/ml x min, p < 0.05) during the total night and aldosterone (3.6 +/- 4.7 ng/ml x min vs. 1.1 +/- 0.9 ng/ml x min, p < 0.05) in the second half of the night, whereas cortisol (8.3 +/- 2.4 pg/ml x min vs. 11.8 +/- 3.8 pg/ml x min, p < 0.01) decreased significantly and AVP by trend in the first part of the night. ACTH and ATII were not altered. Our results suggest that Mg(2+) partially reverses sleep EEG and nocturnal neuroendocrine changes occurring during aging. The similarities of the effect of Mg(2+) and that of the related electrolyte Li+ furthermore supports the possible efficacy of Mg(2+) as a mood stabilizer.
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PMID:Oral Mg(2+) supplementation reverses age-related neuroendocrine and sleep EEG changes in humans. 1216 83

Exposure to hostile conditions initiates responses organized to enhance the probability of survival. These coordinated responses, known as stress responses, are composed of alterations in behavior, autonomic function and the secretion of multiple hormones. The activation of the renin-angiotensin system and the hypothalamic-pituitary-adrenocortical axis plays a pivotal role in the stress response. Neuroendocrine components activated by stressors include the increased secretion of epinephrine and norepinephrine from the sympathetic nervous system and adrenal medulla, the release of corticotropin-releasing factor (CRF) and vasopressin from parvicellular neurons into the portal circulation, and seconds later, the secretion of pituitary adrenocorticotropin (ACTH), leading to secretion of glucocorticoids by the adrenal gland. Corticotropin-releasing factor coordinates the endocrine, autonomic, behavioral and immune responses to stress and also acts as a neurotransmitter or neuromodulator in the amygdala, dorsal raphe nucleus, hippocampus and locus coeruleus, to integrate brain multi-system responses to stress. This review discussed the role of classical mediators of the stress response, such as corticotropin-releasing factor, vasopressin, serotonin (5-hydroxytryptamine or 5-HT) and catecholamines. Also discussed are the roles of other neuropeptides/neuromodulators involved in the stress response that have previously received little attention, such as substance P, vasoactive intestinal polypeptide, neuropeptide Y and cholecystokinin. Anxiolytic drugs of the benzodiazepine class and other drugs that affect catecholamine, GABA(A), histamine and serotonin receptors have been used to attenuate the neuroendocrine response to stressors. The neuroendocrine information for these drugs is still incomplete; however, they are a new class of potential antidepressant and anxiolytic drugs that offer new therapeutic approaches to treating anxiety disorders. The studies described in this review suggest that multiple brain mechanisms are responsible for the regulation of each hormone and that not all hormones are regulated by the same neural circuits. In particular, the renin-angiotensin system seems to be regulated by different brain mechanisms than the hypothalamic-pituitary-adrenal system. This could be an important survival mechanism to ensure that dysfunction of one neurotransmitter system will not endanger the appropriate secretion of hormones during exposure to adverse conditions. The measurement of several hormones to examine the mechanisms underlying the stress response and the effects of drugs and lesions on these responses can provide insight into the nature and location of brain circuits and neurotransmitter receptors involved in anxiety and stress.
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PMID:Neuroendocrine pharmacology of stress. 1260 Jul 14

Menstrually related symptoms and disorders are multidimensional and affect diverse physiologic systems. Elucidation of the pathophysiologic mechanisms of these disorders should allow for a more precise diagnosis, and provide direction for targeted therapeutic interventions. Several biologic mechanisms that underlie menstrually related symptoms have been proposed. They focus mostly on gonadal hormones, their metabolites and interactions with neurotransmitters and neurohormonal systems, such as serotonin, GABA, cholecystokinin, and the renin-angiotensin-aldosterone system. Altered responses of these systems to gonadal hormone's fluctuations during the menstrual cycle, as well as an increased sensitivity to changes in gonadal hormones may contribute to menstrually related symptoms in vulnerable women. Disrupted homeostasis and deficient adaptation may be core underlying mechanisms. Future directions for clinically-relevant progress include identification of specific subgroups of menstrually-related syndromes, assessment of the genetic vulnerability and changes in vulnerability along the life cycle, the diversified mechanisms by which vulnerability is translated into pathophysiology and symptoms, the normalization process as well as syndromes-based and etiology-based clinical trials.
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PMID:The etiology, biology, and evolving pathology of premenstrual syndromes. 1289 90

Abrupt cessation of long-term alcohol consumption produces well-defined symptoms called alcohol withdrawal (AW). The exact pathophysiological mechanisms involved in the appearance of AW symptoms and particularly those related to the precipitation of delirium tremens (DT), still await clarification in spite of the fact that the prediction of complicated AW is essential to guarantee that appropriate therapies may be planned in advance. Changes in central nervous system (CNS) glutamate- and GABA-transmission and a role of voltage-operated calcium channels are equally important elements of neuroadaptation to the chronic presence of alcohol. In addition to the CNS regulation, however, changes in peripheral fluid and electrolyte homeostasis may accompany, and are expected to modify the clinical symptoms of AW. In an early phase of acute withdrawal, plasma levels of atrial natriuretic peptide (ANP), plasma renin activity and aldosterone are high. In patients with DT, elevated levels of ANP were observed days before the actual onset of DT. It is concluded that the altered plasma ANP secretion might be associated with, and therefore used as an indicator of the onset of DT. However, ANP is present in and produced by the brain and thus it can be regarded as a neuropeptide. The role of CNS ANP was studied in mice, rendered tolerant to and physically dependent on alcohol. Intracerebroventricular injections of ANP attenuated, whereas those of an antiserum against ANP intensified hyperexcitability during AW. ANP in the brain - the content of which undergoes sensitive changes in the hippocampus during AW appears to interact primarily with glutamate transmission through the NMDA-receptors. This brain structure is of utmost importance for the generation of withdrawal-related hyperexcitability. It is concluded that peripheral secretion of ANP might be a diagnostics indicator, whereas ANP in the CNS might be a modulator of AW.
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PMID:Natriuretic peptides in alcohol withdrawal: central and peripheral mechanisms. 1452 71


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