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22 results on '"FAVARETTO, A. L. V."'

7. Proc. Natl. Acad. Sci. USA

Author

Haanwinckel, M. A., Elias, L. K., Favaretto, A. L. V., Gutkowska, J., and Mccann, S. M.

Subjects
Kaliuresis, Urine osmolality, Vasopressin, Diuresis
Abstract

p. 7902-7906 Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2013-09-12T19:02:23Z No. of bitstreams: 1 1111111111111s.pdf: 1114424 bytes, checksum: 9c3d34015dad3fcc97a3e0486ee3248a (MD5) Approved for entry into archive by Patricia Barroso(pbarroso@ufba.br) on 2013-09-12T20:18:22Z (GMT) No. of bitstreams: 1 1111111111111s.pdf: 1114424 bytes, checksum: 9c3d34015dad3fcc97a3e0486ee3248a (MD5) Made available in DSpace on 2013-09-12T20:18:22Z (GMT). No. of bitstreams: 1 1111111111111s.pdf: 1114424 bytes, checksum: 9c3d34015dad3fcc97a3e0486ee3248a (MD5) Previous issue date: 1995 Our previous studies have shown that stimulation of the anterior ventral third ventricular region increases atrial natriuretic peptide (ANP) release, whereas lesions of this structure, the median eminence, or removal of the neural lobe of the pituitary block ANP release induced by blood volume expansion (BVE). These results indicate that participation of the central nervous system is crucial in these responses, possibly through mediation by neurohypophysial hormones. In the present research we investigated the possible role of oxytocin, one of the two principal neurohypophysial hormones, in the mediation of ANP release. Oxytocin (1-10 nmol) injected i.p. caused significant, dose-dependent increases in urinary osmolality, natriuresis, and kaliuresis. A delayed antidiuretic effect was also observed. Plasma ANP concentrations increased nearly 4-fold (P < 0.01) 20 min after i.p. oxytocin (10 nmol), but there was no change in plasma ANP values in control rats. When oxytocin (1 or 10 nmol) was injected i.v., it also induced a dose-related increase in plasma ANP at 5 min (P < 0.001). BVE by intra-atrial injection of isotonic saline induced a rapid (5 min postinjection) increase in plasma oxytocin and ANP concentrations and a concomitant decrease in plasma arginine vasopressin concentration. Results were similar with hypertonic volume expansion, except that this induced a transient (5 min) increase in plasma arginine vasopressin. The findings are consistent with the hypothesis that baroreceptor activation of the central nervous system by BVE stimulates the release of oxytocin from the neurohypophysis. This oxytocin then circulates to the right atrium to induce release ofANP, which circulates to the kidney and induces natriuresis and diuresis, which restore body fluid volume to normal levels. Salvador

Published
1995

15. Is Ovarian Adrenergic Innervation Essential to Gonadal Function in Adult Rats?

Author

Albuquerque-Araujo, W. I. C., Rosa-e-Silva, A. A. M., Antunes-Rodrigues, J., and Favaretto, A. L. V.

Abstract

We studied the relative importance of ovarian innervation during different phases of female rat sexual development, 30, 40, 45 and 60-day-old. Chemical sympathectomy was promoted by long term postnatal treatment with guanethidine (CD), an adrenergic neuron blocking agent. The sympathectomized rats exhibited delayed puberty and alterations in estrous cycle. Reduced circulating E2, LH and Prl levels at 30 days of age were observed, besides decreased steroidal secretory responsiveness to gonadotropins in vitro. On the other hand, normal pituitary secretory responsiveness to LHRH in vivo and plasma gonadotropin concentrations were observed in 60-day-old rats. These data reinforce the view that ovarian sympathetic innervation contributes to the regulation of the prepubertal development of the ovarian functions.

Published
1995
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16. Morphometric and biochemical evaluation of rat prostate and seminal vesicle following chemical sympathectomy with guanethidine

Author

Carvalho, T. L. Lamano, Petenusci, S. O., Favaretto, A. L. V., and Kempinas, W. G.

Abstract

Selective chemical sympathectomy of the internal genital organs of adult male rats was undertaken by chronic treatment with low doses of guanethidine. Biochemical and morphometric methods revealed that removal of sympathetic innervation prevents fructose secretion in the prostate and seminal vesicle, in addition to promoting reduced efficiency of delivery by the latter.

Published
1990
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20. Inhibitory role of cholinergic agonists on testosterone secretion by purified rat Leydig cells

Author

Favaretto, A. L. V., Valença, M. M., Picanço-Diniz, D. L. W., and Antunes-Rodrigues, J.

Abstract

The effects of cholinometics on basal or hCG-induced testosterone (T) release by Percollpurified Leydig cells of the rat were studied. Acetylcholine and carbachol as well as nicotine decreased basal and hCG-induced T secretion. The ganglionic nicotine antagonist hexamethonium promoted a partial reversal of the inhibitory effect of nicotine on basal or hCG-stimulated T secretion. Atropine also reduced the inhibitory effect of carbachol on basal or stimulated androgen release.These data indicate that, in short-term incubations, testosterone released by purified Leydig cells is inhibited by nicotinic and muscarinic cholinergic agonists, thus supporting the hypothesis that parasympathetic autonomic system may be involved in the negative regulation of testicular androgen secretion.

Published
1993
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22. Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat.

Author

Picanço-Diniz DL, Valenca MM, Favaretto AL, and Antunes-Rodrigues J

Subjects
Adenylyl Cyclases pharmacology, Animals, Lipoxygenase pharmacology, Male, Pituitary Gland, Anterior physiology, Prostaglandin-Endoperoxide Synthases pharmacology, Rats, Rats, Wistar, Adenosine pharmacology, Pituitary Gland, Anterior drug effects, Prolactin metabolism
Abstract

We investigated the effects of adenosine on prolactin (PRL) secretion from rat anterior pituitaries incubated in vitro. The administration of 5-N-methylcarboxamidoadenosine (MECA), an analog agonist that preferentially activates A2 receptors, induced a dose-dependent (1 nM to 1 microM) increase in the levels of PRL released, an effect abolished by 1,3-dipropyl-7-methylxanthine, an antagonist of A2 adenosine receptors. In addition, the basal levels of PRL secretion were decreased by the blockade of cyclooxygenase or lipoxygenase pathways, with indomethacin and nordihydroguaiaretic acid (NDGA), respectively. The stimulatory effects of MECA on PRL secretion persisted even after the addition of indomethacin, but not of NDGA, to the medium. MECA was unable to stimulate PRL secretion in the presence of dopamine, the strongest inhibitor of PRL release that works by inducing a decrease in adenylyl cyclase activity. Furthermore, the addition of adenosine (10 nM) mimicked the effects of MECA on PRL secretion, an effect that persisted regardless of the presence of LiCl (5 mM). The basal secretion of PRL was significatively reduced by LiCl, and restored by the concomitant addition of both LiCl and myo-inositol. These results indicate that PRL secretion is under a multifactorial regulatory mechanism, with the participation of different enzymes, including adenylyl cyclase, inositol-1-phosphatase, cyclooxygenase, and lipoxygenase. However, the increase in PRL secretion observed in the lactotroph in response to A2 adenosine receptor activation probably was mediated by mechanisms involving regulation of adenylyl cyclase, independent of membrane phosphoinositide synthesis or cyclooxygenase activity and partially dependent on lipoxygenase arachidonic acid-derived substances.

Published
2002
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