Vp. Markowski et al., PRENATAL COCAINE EXPOSURE PRODUCES GENDER-SPECIFIC MOTOR EFFECTS IN AGED RATS, Neurotoxicology and teratology, 20(1), 1998, pp. 43-53
This investigation employed a longitudinal analysis of a complex motor
skill in rats that were exposed prenatally to cocaine. Offspring were
derived from four maternal treatment groups: 50 mg/kg cocaine, their
pair-fed controls, 25 mg/kg cocaine, and freely fed controls. Cocaine
was administered via gavage from gestation day 6-20. A maternal foster
ing procedure was used. Pairs of male and female littermates began tra
ining when 9, 13, or 19 months old. The behavioral procedure involved
fixed-ratio (FR) lever pressing to obtain brief periods of wheel runni
ng. The oldest males from the 50 mg/kg, 25 mg/kg, and pair-fed groups
performed significantly fewer wheel revolutions per opportunity than f
emales or freely fed males. In general, animals earned fewer opportuni
ties to run as the FR requirement was increased over sessions. However
, within each age-by-gender group, subjects from the four treatment gr
oups performed equivalent amounts of lever pressing. The specific effe
ct on the motor aspect of the procedure may have resulted from a reduc
tion of motor coordination, balance, or strength, or a diminished capa
city of wheel running to serve as a reinforcing stimulus in a cocaine-
sensitive subgroup. (C) 1998 Elsevier Science Inc.