Sequential changes of skin conductance activity in rats after intraventricular administration of 6-hydroxydopamine

Thirty two male Wistar strain rats were trained to have their skin conductance activity recorded through the soles of their hind limbs, and sequential changes of this activity after the intraventricular administration of 6-OHDA (200 micrograms) were studied. The intact rats showed SCR and its habituation to repeated auditory stimuli (500 Hz, 90 dB, 1 sec). The 6-OHDA treatment obliterated SCR and reduced the rate of spontaneous fluctuation in the early stage after the treatment. From the second day to one week after the treatment, with recovery of the spontaneous fluctuation rate, the SCR tended to reappear, and its habituation gradually slowed down. Two and three weeks after the treatment, the 6-OHDA rats usually showed habituation failure of SCR, but default of SCR was still observed at times. These findings suggest that denervation of the catecholaminergic fibers by intraventricular 6-OHDA is responsible for the obliteration of SCR, and denervation supersensitivity, which develops later, may be the cause of its habituation failure. The mechanisms underlying abnormal skin conductance activity of schizophrenia were discussed in line with the catecholamine hypothesis of this disease.