Psychoneuroendocrine effects of neurotoxic lesions in the septum and striatum of rats

Abstract

The psychoneuroendocrine effects of electrolytic septal lesions were compared with neurotoxic lesions in the lateral septum or striatum of rats induced by 6-hydroxydopamine (6-OHDA) or kainic acid (KA). Lesion effects were examined in terms of changes in body weight (BWt) regulation, ovarian compensatory hypertrophy (OCH) and female sexual behavior. Septal injections of 6-OHDA selectively reduced septal levels of dopamine (DA) by 60% whereas striatal injections reduced striatal levels of DA by 77% and septal levels by 30%. Significant effects of these various lesions were relative to controls (1) KA lesions in the septum increased and 6-OHDA lesions in the striatum decreased BWt; (2) 6-OHDA lesions in the striatum reduced ovarian weight and KA lesions in the septum increased OCH; (3) electrolytic septal lesions increased and KA septal lesions decreased female sexual behavior; (4) the effects of estrogen on food intake and BWt were attenuated in KA septal lesioned rats. Since this experiment failed to show an inhibitory role for DA on lordotic behavior, in a second experiment brain levels of DA were depleted by 6-OHDA injections in the ventral tegmental area or substantia nigra. Levels of female sexual behavior for these animals were comparable to controls. Thus, decreases in brain levels of DA previously shown to associated with electrolytic septal lesions may not be causally related to the observed increase in lordotic behavior. Lateral septal damage induced by KA appears to modify a variety of estrogen-sensitive systems.