Influence of sex and female hormones on nicotine-induced changes in locomotor activity in rats.
The acute and chronic effects of nicotine (0.4 mg/kg s.c.) on locomotor activity in photocell cages have been compared in male, female, and ovariectomized hooded rats. In Experiment 1, female rats displayed higher locomotion than males (n = 12); acutely, nicotine-reduced locomotion, and this effect was slightly larger in females than males. Daily administration of nicotine for 21 days produced a similar, gradual increase in activity in both sexes. Tests then confirmed greater activity in females than males and as a function of previous chronic exposure to nicotine (n = 6); there was an activating effect of nicotine challenge but no interaction of nicotine effects with sex. In Experiment 2, ovariectomized rats were primed with 17-beta-estradiol (50 microg/kg s.c.) and progesterone (2.5 mg/kg s.c.) or vehicle only. Acute administration of nicotine reduced activity in both groups similarly (n = 12). After nicotine daily for 21 days, there was increased activity as a function of both chronic nicotine and hormonal priming, and challenge with nicotine increased activity (n = 6). The effects of these challenges with nicotine were also slightly greater, as a function of previous nicotine exposure and priming. As a whole, these experiments showed robust effects of acute and chronic nicotine administration, sex, and hormonal priming; neither sex nor gonadal hormones had marked influences on changes in locomotor activity produced by nicotine.
Kanýt
L
L
EGE University Center for Brain Research, School of Medicine, Department of Physiology, Bornova, Izmir, Turkey.
Stolerman
I P
IP
Chandler
C J
CJ
Saigusa
T
T
Pöğün
S
S
D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D012737:Sex Factors