Leptin stimulates LH secretion in peripubertal male rats through NMDA receptors.
Leptin, a peptide hormone secreted by adipocytes that has been proposed as a metabolic signal in the reproductive system, appears to be linked to the different neuroendocrine processes involved in the onset of puberty. We studied the ontogenic effect of administration of leptin (30 mg/kg i.p.) on serum LH levels during different stages of sexual development (7, 30, and 45 days of age) in male rats and on the hypothalamic content of glutamate (GLU) and gamma-aminobutyric acid (GABA) in 30-day-old rats. Leptin induced a significant increase (p < 0.01) in LH levels in 30 days old rats. This hormone stimulatory effect was accompanied by a significant enhancement (p < 0.01) of the hypothalamic content of glutamate, the hypothalamic excitatory aminoacid involved in N-methyl-D-aspartate (NMDA) neurotransmission. No changes in the LH plasma levels were observed in 7- and 45-day-old male rats treated with leptin. MK 801 (0.1 and 0.3 mg/kg i.p.), an antagonist of NMDA receptors of excitatory amino acid system (EAAs), antagonized the stimulatory effect of leptin on LH secretion and on the hypothalamic content of GLU. These results demonstrate that leptin stimulates the reproductive axis in male rats during a determined period of sexual maturation and that NMDA receptors are involved in thefacilitatory action of leptin on the gonadal axis of male rats during sexual maturation.
Carbone
Silvia
S
Departamento de Fisiologia, Facultad de Medicina, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina.
Szwarcfarb
Berta
B
Reynoso
Roxana
R
Bollero
Gabriela
G
Ponzo
Osvaldo
O
Rondina
Dora
D
Scacchi
Pablo
P
Moguilevsky
Jaime
J
D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D020738:Leptin / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D008297:Male; D018696:Neuroprotective Agents / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012741:Sexual Maturation / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D020738:Leptin; D018696:Neuroprotective Agents; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D016291:Dizocilpine Maleate; D007986:Luteinizing Hormone