Sex differences in the asymmetry of the Nigrostriatal Dopamine system : relationship to spatial ability in the rat

The present study investigated the relationship between the asymmetry of the nigrostriatal dopamine system, amphetamine-induced rotation and spatial ability. In addition, the influence of the gonadal hormones on this relationship was investigated. Half of the 40 female and of the 40 male Wistar rats were gonadectomized while the remaining underwent a sham operation. The rats were tested on two consecutive weeks for their rotational behavior following administration of amphetamine (1.2 mg/kg). Spatial ability was measured on a modified Lashley III maze for half of the animals. The remaining animals were tested on the Morris Water maze. Followingcompletion of the tests of spatial ability, the animals were sacrificed by decapitation and their brains (right and left striata and right and left frontal cortices) were dissected, and later assayed for their contents of DA and NE by the fluorometric method. Gonadectomy was found to increase striatal DA levels, and to influence performance of male rats on the Lashley III maze. The relationship between spatial ability and the asymmetry of the DA system was task-specific since a correlation was found only with performance on the Lashley III maze and not on the Morris Water maze. The results also showed that the relationship between rotation and spatial ability was influenced by the sex and the treatment of the animals.