Aging results in attenuated gonadotropin releasing hormone-luteinizing hormone axis responsiveness to glutamate receptor agonist N-methyl-D-aspartate.

摘要: Reproductive aging in the Brown Norway rat occurs because of testicular as well hypothalamic-pituitary dysfunction. Excitatory amino acids (EAA) participate regulation pulsatile secretion hypothalamic GnRH and pituitary LH. In present study, we studied EAA-GnRH-LH axis for possible age-related alterations prepubertal (35 days), young (3-4 months), middle-aged (12-13 months) old (21-23 rats. first experiment, an intra-atrial cannula was implanted rats different ages to evaluate response small, physiological intravenous bolus administration (0.5 or 1.0 nmol/100 g body weight). The results showed no significant differences in-vivo serum LH FSH responsiveness GnRH. a second blood samples gonadotropins were withdrawn immediately before 10 min after iv injection glutamate receptor agonist N-methyl-D-aspartate (NMDA; 5 mg/kg, dose that induces pulse rats). Administration NMDA induced increases prolactin all groups animals (P<0.05) but not NMDA-induced LH, release higher than other age groups. Compared with rats, increase plasma lower third ascertain whether this reduced exerted at level, effects on vitro from preoptic area-medial basal hypothalamus (POA-MBH) fragments compared among ages. efflux significantly attenuated increasing age. (P<0.05). Lastly, measured acid concentrations tissue (POA-MBH fragments). Prepubertal had levels taurine Significant reductions gamma-aminobutyric (GABA) found conclusion, these NMDA-GnRH-LH altered decreased content some EAA neurons (both vivo vitro) may contribute observed