INVESTIGADORES
BREGONZIO DIAZ Claudia
artículos
Título:
NMDA receptor antagonists block stress induced PRL release in female rats at estrus
Autor/es:
3. BREGONZIO, C.; NAVARRO, C. E.; DONOSO, A.O
Revista:
EUROPEAN JOURNAL OF PHARMACOLOGY
Referencias:
Año: 1998 vol. 350 p. 259 - 265
ISSN:
0014-2999
Resumen:
In order to evaluate the role of glutamate in prolactin secretion, we examined
the effects of N-methyl-D,L-aspartic acid (NMDA) receptor antagonists on serum
prolactin levels at both resting and restraint-stress conditions in female rats
at estrus. NMDA increased basal serum prolactin levels. Administration of the
selective NMDA receptor antagonist, cis-4-phosphonomethyl-2-piperidine
carboxylic acid (CGS 19755) (5 and 10 mg/kg i.p.), to rats under resting
conditions enhanced basal prolactin levels. A low dose of CGS 19755 (3 mg/kg)
was unable to modify the hormone serum level. Under stress conditions the
pretreatment with CGS 19755 (3 and 5 mg/kg) prevented the increase in serum
prolactin levels. This effect was reversed by NMDA (60 mg/kg s.c.). The NMDA
receptor antagonist (5 mg/kg) decreased the median eminence concentration of the
dopamine metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), without modifying
dopamine content. To examine the probable link between serotonin (5-HT) and
glutamate in prolactin release, the 5-HT2A/5-HT2C receptor antagonist,
ritanserin, was used. Under resting conditions, a dose of 5 mg/kg s.c. blocked
the NMDA-induced prolactin release. In rats submitted to restraint, ritanserin
decreased the prolactin response and NMDA was unable to correct the stress serum
prolactin levels. The 5-HT1A receptor agonist, 8-hidroxypropyl-amino tetralin
(8-OH-DPAT) (3 mg/kg s.c.), increased basal serum prolactin levels and restored
serum prolactin in stressed animals pretreated with CGS 19755 (5 mg/kg). The
present data strongly suggest that the glutamatergic system participates in the
regulation of prolactin secretion. A stimulation tone seems to be exerted via
the tuberoinfundibular dopaminergic system, and the prolactin release evoked by
restraint apparently involves glutamate/NMDA receptors linked to a
serotoninergic pathway.