Hypothalamic nitric oxide synthase activity during sexual maturation in female rats. Effects of estrogens.
OBJECTIVE
To determine the hypothalamic activity of nitric oxide synthase (NOS, the enzyme involved in the synthesis of nitric oxide NO) during sexual maturation in prepubertal (15 days old) and peripubertal female rats (30 days old) as well as the effect of estradiol administration on this neurotransmitter system.


METHODS
Hypothalamic samples containing the anterior preoptic and medial basal areas (APOA-MBH) were homogenized with HEPES 20 mM, pH = 7.4 and NOS activity was determined in APO-MBH after 10 minutes of incubation by the conversion of 14C arginine to 14C citrulline.


RESULTS
The hypothalamic concentration of NOS is significantly higher in peripubertal than in prepubertal rats. Treatment with EB increased significantly the activity of the enzyme in both groups compared with control and the increases was similar at both ages.


CONCLUSIONS
These results clearly demonstrated that the hypothalamic NOS activity increases in peripubertal rats as compared with prepubertal animals. Estradiol has a similar stimulatory effect on hypothalamic NOS activity at both ages of sexual maturation, indicating that the increase in NOS during sexual maturation is connected with the peripubertal increase of estradiol rather than an increase in the sensitivity of the enzyme to the ovarian hormone.
Reynoso
Roxana
R
Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
Mohn
Claudia
C
Szwarcfarb
Berta
B
Ponzo
Osvaldo
O
Carbone
Silvia
S
Scacchi
Pablo
P
Moguilevsky
Jaime A
JA
D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007031:Hypothalamus / Q000201:enzymology*; D051381:Rats; D017208:Rats, Wistar; D012741:Sexual Maturation / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects
D004958:Estradiol