Effects of d- and l-amphetamine on dorsal and ventral hypothalamic self-stimulation in three inbred strains of mice.

The effects of intraperitoneal injections of increasing doses of d- and l-amphetamine on self-stimulation behaviour in dorsal and ventral hypothalamic areas, were studied in BALB/c Orl., DBA/2 Orl, and C57BL/6 Orl inbred mice. Both isomers improved and disrupted self-stimulation as a function of the doses injected. However, the improvements obtained with d-amphetamine were higher than those obtained with 1-amphetamine. In contrast the 1 isomer generally provoked the highest disruptions. In addition, the three strains presented various sensitivities to d-amphetamine, which improved self-stimulation first in BALB/c (0.25 and 0.50 mg/kg), then in DBA/2 (0.50 and 1.0 mg/kg) and finally in C57BL/6 (2.0, 4.0 and 8.0 mg/kg). The dorsal hypothalamic self-stimulation system presented a greater sensitivity to d-amphetamine than the ventral system; while the two reward systems reacted identically to 1-amphetamine. The differential effects observed are set into relationship with neurochemical data concerning the central catecholaminergic mechanisms.