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Biomedical subjects

M Coculescu

Publications and source records attributed to M Coculescu.

At least 19 recordsLinked to original sources
PubMed1994

The effects of [Arg8]vasopressin and [Arg8]vasotocin on the firing rate of suprachiasmatic neurons in vitro.

The excitatory effect of [Arg8]-vasopressin and its potential contribution to the circadian cycle of electrical activity in the suprachiasmatic nucleus of the rat was investigated using extracellular recordings from hypothalamic slices from virgin female rats. The majority of neurons tested for their responses to vasopressin and [Arg8]-vasotocin displayed coincident, dose-dependent excitation by both peptides, although the relative efficacy varied between neurons, with some showing a highly preferential excitation by vasotocin. Perifusion with the vasopressin receptor antagonist d(CH2)5[Tyr(OEt)2,Val4,Cit8]-vasopressin was able to block the majority of responses to vasopressin or vasotocin (20/25), and similar excitation could be induced by the selective agonist [Phe2,Orn8]-vasotocin, indicating a mainly V1 receptor-mediated effect. Few neurons (3/27; 11%) responded to the oxytocin-specific agonist, [Thr4,Gly7]-oxytocin, suggesting a low occurrence of oxytocin receptors. In addition to blocking the action of exogenous vasopressin, the V1 antagonist caused a reversible suppression of spontaneous basal activity in 7/25 cases, consistent with the presence of an endogenous excitatory vasopressin tone. In agreement with previous reports, the activity of suprachiasmatic nucleus neurons showed a significant correlation between spontaneous activity and the light-dark cycle, with activity decreasing during the subjective dark phase. When neurons were divided on the basis of their response to vasopressin and/or vasotocin, the peptide-sensitive neurons continued to show a strong correlation (r = 0.513, P < 0.01) while the insensitive neurons showed no correlation (r = 0.136, P > 0.05). These data confirm the presence of V1 type receptors in the suprachiasmatic nucleus and also indicate a small number of neurons possessing additional classes of receptor selective for either oxytocin or vasotocin. Contrary to previous reports, they also demonstrate that endogenous vasopressin tonically excites suprachiasmatic nucleus neurons. The fact that vasopressin-sensitive (but not vasopressin-insensitive) neurons show a level of basal activity correlated with time, suggests that this tone may contribute to the circadian cycle of electrical activity in the suprachiasmatic nucleus.

Action Potentials↗
PubMed1982

Gonadotropins in rats with hereditary diabetes insipidus (Brattleboro strain).

In the Brattleboro strain of rats, the genetic defect in vasopressin synthesis seems to be accompanied by a defect in the synthesis of other structurally related nonapeptides, such as the pineal arginine vasotocin which has antigonadotropic properties in animals. It was therefore tempting to investigate gonadotropin secretion in rats with hereditary hypothalamic diabetes insipidus (DI rats).

Animals↗
PubMed1981

Possible hormonal role of the angiotensin-like peptides in mammals' pineal gland.

An isorenin is synthetized in the pineal gland cells. The amount of isorenin as well as the synthesis of angiotensin I and II in the pineal gland depends on the circadian rhythm, osmotic stimuli and stimulation of the cervical sympathetic postganglionar fibres. Pineal angiotensin is released both into the blood and in the cerebrospinal fluid (CFS). The major site of the pineal angiotensin action are the circumventricular organs, the preiventricular receptors of the anterior hypothalamus and the epiphysis cerebri itself. Except its participation in regulating arterial pressure and the hydroelectrolytic metabolism, through its central effects on the brain, pineal angiotensin-like peptides also participate in the pool of circulating angiotensin and it may represent Farrell's pineal glomerulotropic factor.

Angiotensin I↗
PubMed1979

Influence of arginine vasotocin administration on nocturnal sleep of human subjects.

Arginine vasotocin (AVT) or placebo were subcutaneously administered to 4 men at 22.00 and 01.00 h, along four nights, and polygraphic recordings were performed between 22.00 and 02.00 h during sleep. AVT significantly increased only the amount of rapid eye movement (REM) sleep (p less than 0.05), but did not influence the latency of the first REM sleep period. This effect of AVT was not dose dependent in the range between 2 and 12 microgram AVT. AVT or placebo were also intravenously injected or perfused to 10 normal adult subjects, at different times of the day, under clinical control. Doses between 2 microgram perfused 4 h and 12 microgram perfused 30 min, did not produce clinical signs of sleep. It is suggested that AVT is not a blood factor for inducing of slow waves sleep (SWS) or REM sleep in humans.

Adult↗
PubMedDate not supplied

Psychoneuroendocrine stress-induced syndromes.

Psychoneuroendocrine stress-induced syndromes were characterised as expression of the activity of neuroendocrine transducers. A physiopathologic classification delineated the diseases which appeared as a result of the increase of the endocrine response to acute stress, i.e., catecholamine cardiomyopathy, reactive hypercortisolism, amenorrhea, infertility, sexual dysfunction of euthyroid sick syndrome in man and immunosuppression. The clinical diseases secondary to chronic stress, together with their physiopathologic therapy, i.e., central hypocorticism and psychosocial dwarfism, are described. They are produced by active inhibition of the endocrine response mechanism called by us: dysprotection.

Endocrine System Diseases↗
PubMedDate not supplied

Tentative identification of arginine vasotocin in the bovine pineal extract prepared by in the bovine pineal extract prepared by the Milcu-Nanu method.

The bovine pineal extract prepared by the Milcu-Nanu method (BPE-MN) has frog bladder, rat antidiuretic and rat uterine activities susceptible to tryptic digestion. The ratios of these activities are characteristic of arginine vasotocin (AVT). Desalting on Amberlite CG25 and partial purification of BPE-MN by free-flow continuous electrophoresis (FFCE) allow the separation of some fractions with AVT-like biological activities and with a carrier-free electrophoretic mobility similar to the synthetic AVT. The results strongly suggest the presence of AVT in the bovine pineal extract prepared by the Milcu-Nanu method.

Animals↗