Effects of amphetamine on locomotor activity in adult and juvenile alcohol-preferring and -nonpreferring rats.
The objective of this study was to determine whether functional differences exist in amphetamine-induced locomotor activity between alcohol-naive alcohol-preferring (P) and -nonpreferring (NP) rats during postnatal development and during adulthood. Using a between-subjects design, 20- and 28-day-old P and NP rats (male and female counterbalanced, n=11-16/line) were habituated for 30 min in a photocell activity field. Each rat received subcutaneous injections of saline or 0.3, 0.6 or 1.2 mg/kg d-amphetamine (AMPH) and were then tested for an additional 30 min. Because of age and line differences in basal locomotor activity, total activity counts during the 30-min postdrug period were standardized using Z-score transformations. In the 20- and 28-day-old rats, dose-dependent locomotor activity increases after AMPH injections were obtained at both ages, although activity levels were greater in the 20-day-old pups. The 20-day-old female NP rats showed greater AMPH-induced increases in locomotor activity than P rats, whereas at 28 days of age, male NP rats showed greater activity levels than P rats to AMPH. For the adult P and NP rats (n=8/line/gender), a within-subject design was used. In the adults, the NP line had higher locomotor activity than the P line following AMPH injection, and male rats were activated more by AMPH than female rats. The results suggest that functioning of the DA system in the adult P line is reduced compared to the adult NP line, and this line difference is also observed to some degree at an early postweaning developmental period.
McKinzie
D L
DL
Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202-4887, USA.
McBride
W J
WJ
Murphy
J M
JM
Lumeng
L
L
Li
T-K
TK
D000375:Aging / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D000428:Alcohol Drinking / Q000235:genetics*; D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D012737:Sex Factors; D013045:Species Specificity
D018765:Dopamine Uptake Inhibitors; D000661:Amphetamine