FUNCTIONAL INFLUENCE OF THE CENTRAL NORADRENERGIC SYSTEM ON THE SKIN-CONDUCTANCE ACTIVITY IN RATS

Pharmacological studies on neuroleptics and amphetamine strongly sugge st that some dysfunction of the central catecholamine system may play a key role in the pathogenesis of schizophrenia. Our previous studies have demonstrated that intraventricular administration of 6-hydroxydop amine, a selective neurotoxin of the catecholamine neuron, can reprodu ce schizophrenia-like abnormalities in the skin conductance activity. In the present experiments, effects of pharmacological modulation of t he central noradrenergic activity were studied in rats. Stimulation of the central noradrenergic activity by yohimbine (0.6 mg/kg, i.m.) slo wed down the habituation of the skin conductance response (SCR) and in crease the spontaneous fluctuation of the skin conductance (SF), while inhibition of the activity by clonidine (0.06 mg/kg, i.m.) accelerate d or obliterated the SCR and decreased the SF frequency. If the functi onal significance of the central noradrenergic system lies in vigilanc e control, the present results are consistent with classical theory in psychophysiology: the habituation rate of SCR and the frequency of SF are correlated well with each other and both indices reflect arousal level. The disorder of the system should produce not only these psycho physiological abnormalities but also psychological disturbances; i.e., overarousal and underarousal syndromes. Therefore, the dysfunction of the noradrenergic system might constitute an essential aspect of schi zophrenic disorder.