Effects of gabaergic and serotoninergic systems on hypothalamic content of catecholamines during sexual development in female rats.
OBJECTIVE
The aim of the present investigation was to determine whether the catecholaminergic system is involved in gabaergic and serotoninergic effects on gonadotrophin secretion during sexual development. To this end, we studied the effect of GABAergic and serotoninergic systems on hypothalamic catecholamine content at different stages of sexual development.


METHODS
The effect of GABA A and GABA B agonists and 5-hydroxy-L-tryptophan on hypothalamic noradrenaline and dopamine content were determined in prepubertal (16 days old) and peripubertal (30 days old) rats.


RESULTS
At 16 days of age GABA agonists did not modify hypothalamic noradrenaline content, whereas a significant decrease in catecholamine concentration was observed in peripubertal rats at 30 days of age. Similar changes were observed with GABA agonists administration on dopamine hypothalamic levels, i.e no effects at 15 days of age and a significant decrease at 30 days. The administration of 5-hydroxy-l-tryptophan (5-HTP) induced a decrease of hypothalamic concentration of noradrenaline and dopamine at both ages.


CONCLUSIONS
Results indicate that the GABAergic system modifies the hypothalamic catecholamine content in peripubertal but not in prepubertal rats while serotonin has an inhibitory effect at both stages of sexual maturation. Even though both systems induce similar ontogenic modifications on the gonadotrophin axis (stimulatory effect in prepubertal and inhibitory action in peripubertal and adult rats) the present results appear to indicate that GABAergic and serotoninergic systems regulate gonadotrophin secretion by different hypothalamic mechanisms.
Rondina
Dora
D
Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, 1121.Buenos Aires, ARGENTINA.
Ponzo
Osvaldo J
OJ
Szwarcfarb
Berta
B
Carbone
Silvia
S
Scacchi
Pablo
P
Moguilevsky
Jaime A
JA
D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism; D005260:Female; D018755:GABA Agonists / Q000494:pharmacology; D007031:Hypothalamus / Q000254:growth & development* / Q000378:metabolism*; D009118:Muscimol / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000187:drug effects; D018080:Receptors, GABA-B / Q000187:drug effects; D012701:Serotonin / Q000502:physiology*; D012741:Sexual Maturation / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D002395:Catecholamines; D018755:GABA Agonists; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D009118:Muscimol; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D001418:Baclofen; D004298:Dopamine; D009638:Norepinephrine