Chronic D-amphetamine induces sexually dimorphic effects on locomotion, recognition memory and brain monoamines

V. BISAGNO; D. FERGUSON; V.N. LUINE

PHARMACOLOGY BIOCHEMISTRY AND BEHAVIOR

Elsevier

Lugar: New York; Año: 2003 vol. 74 p. 859 - 867

0091-3057

While acute and chronic d-amphetamine treatments produce greater scores for locomotor activity in female rats in comparison with male rats, little is known about AMPH induced gender differences on cognition. The objectives of the present study were: (1) investigate during a withdrawal period following chronic d-amphetamine (AMPH) treatment wether performance of two memory tasks, object recognition (OR) and object placement (OP) are altered, and (2) determine if an AMPH challenge dose after a withdrawal period amplifies previously reported gender differences in locomotor activity and neurochemistry. Sprague-Dawley male and female adult rats were included in a chronic d-amphetamine treatment (10 injections, one every other day; males: 3mg/kg, females 2.6 mg/kg). Locomotor activity was quantified (acute, chronic and after a 16-day withdrawal period). Neurotransmitter levels in brain areas were evaluated after an AMPH challenge dose on the 16th withdrawal day. During the withdrawal period OR (2 and 4 h delays) was impaired in AMPH treated males but they did not show any impairment in OP; AMPH females also showed impairments in OR (only 4 h delay). AMPH females showed more locomotion after acute and chronic treatment but AMPH-induced hyperactivity was comparable for females and males after a challenge dose. Following a challenge dose of AMPH after a withdrawal period gender differences in dopaminergic and serotonergic neurotransmission in the striatum were found. These gender differences elicited by AMPH in monoaminergic pathways may be related to sex differences on behavioral components involved in locomotion and object recognition memory.