Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
NITRIC-OXIDE INHIBITS THE RELEASE OF NOREPINEPHRINE AND DOPAMINE FROMTHE MEDIAL BASAL HYPOTHALAMUS OF THE RAT
Autore:
SEILICOVICH A; LASAGA M; BEFUMO M; DUVILANSKI BH; DIAZ MD; RETTORI V; MCCANN SM;
Indirizzi:
UNIV TEXAS,SW MED CTR,DEPT INTERNAL MED,5323 HARRY HINES BLVD DALLAS TX 75235 UNIV TEXAS,SW MED CTR,DEPT INTERNAL MED DALLAS TX 75235 UNIV BUENOS AIRES,FAC MED,CTR INVEST REPROD RA-1121 BUENOS AIRES DF ARGENTINA CONSEJO NACL INVEST CIENT & TECN,CEFYBO,CONSEJO NACL INVEST CIENT & TECN RA-1414 BUENOS AIRES DF ARGENTINA LAB BIOCIENCIA BUENOS AIRES DF ARGENTINA
Titolo Testata:
Proceedings of the National Academy of Sciences of the United Statesof America
fascicolo: 24, volume: 92, anno: 1995,
pagine: 11299 - 11302
SICI:
0027-8424(1995)92:24<11299:NITRON>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
HORMONE-RELEASE; LH; INVOLVEMENT; PROLACTIN;
Keywords:
NITROPRUSSIDE; N-G-MONOMETHYL-L-ARGININE; ELEVATED-[K+] MEDIUM; TISSUE CATECHOLAMINE CONCENTRATION; HEMOGLOBIN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
21
Recensione:
Indirizzi per estratti:
Citazione:
A. Seilicovich et al., "NITRIC-OXIDE INHIBITS THE RELEASE OF NOREPINEPHRINE AND DOPAMINE FROMTHE MEDIAL BASAL HYPOTHALAMUS OF THE RAT", Proceedings of the National Academy of Sciences of the United Statesof America, 92(24), 1995, pp. 11299-11302

Abstract

Previous research indicates that norepinephrine and dopamine stimulate release of luteinizing hormone (LH)-releasing hormone (LHRH), which then reaches the adenohypophysis via the hypophyseal portal vessels torelease LH. Norepinephrine exerts its effect via alpha(1)-adrenergic receptors, which stimulate the release of nitric oxide (NO) from nitricoxidergic (NOergic) neurons in the medial basal hypothalamus (MBH). The NO activates guanylate cyclase and cyclooxygenase, thereby inducingrelease of LHRH into the hypophyseal portal vessels. We tested the hypothesis that these two catecholamines modulate NO release by local feedback. MBH explants were incubated in the presence of sodium nitroprusside (NP), a releaser of NO, and the effect on release of catecholamines was determined. NP inhibited release of norepinephrine. Basal release was increased by incubation of the tissue with the NO scavenger hemoglobin (20 mu g/ml). Hemoglobin also blocked the inhibitory effect of NP. In the presence of high-potassium (40 mM) medium to depolarize cell membranes, norepinephrine release was increased by a factor of 3, and this was significantly inhibited by NP. Hemoglobin again produced a further increase in norepinephrine release and also blocked the action of NP. When constitutive NO synthase was inhibited by the competitive inhibitor N-G-monomethyl-L-arginine (NMMA) at 300 mu M, basal release of norepinephrine was increased, as was potassium-evoked release, and this was associated in the latter instance with a decrease in tissue concentration, presumably because synthesis did not keep up with theincreased release in the presence of NMMA. The results were very similar with dopamine, except that reduction of potassium-evoked dopamine release by NP was not significant, However, the increase following incubation with hemoglobin was significant, and hemoglobin, when incubated with NP, caused a significant elevation in dopamine release above that with NP alone. In this case, NP increased tissue concentration of dopamine along with inhibiting release, suggesting that synthesis continued, thereby raising the tissue concentration in the face of diminished release. When the tissue was incubated with NP plus hemoglobin, which caused an increase in release above that obtained with NP alone, the tissue concentration decreased significantly compared with that in the absence of hemoglobin, indicating that, with increased release, release exceeded synthesis, causing a fall in tissue concentration. When NO synthase was blocked by NMMA, the release of dopamine, under eitherbasal or potassium-evoked conditions, was increased. Again, in the latter instance the tissue concentration declined significantly, presumably because synthesis did not match release. Therefore, the results were very similar with both catecholamines and indicate that NO acts to suppress release of both amines. Since both catecholamines activate the release of LHRH, the inhibition of their release by NO serves as an ultra-short-loop negative feedback by which NO inhibits the release ofthe catecholamines, thereby reducing the activation of the NOergic neurons and decreasing the release of LHRH. This may be an important means for terminating the pulses of release of LHRH, which generate the pulsatile release of LH that stimulates gonadal function in both male and female mammals.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/03/20 alle ore 15:01:30