SMALL DOSES OF APOMORPHINE AND CHRONIC ADMINISTRATION OF D-AMPHETAMINE REDUCE LOCOMOTOR HYPERACTIVITY PRODUCED BY RADIOFREQUENCY LESIONS OF DOPAMINERGIC A10 NEURONS AREA

  • 1 January 1977
    • journal article
    • research article
    • Vol. 12  (6) , 719-732
Abstract
Lesion of the ventral mesencephalic tegmentum region (VMT) in the rat induces a behavioral syndrome characterized mainly by locomotor hyperactivity and reduction of attention processes. This syndrome was due at least in part to the destruction of dopaminergic (DA) A10 neurons. The effects of two dopaminomimetic drugs, apomorphine (APO) and d-amphetamine (d-AMPH), on the VMT behavioral syndrome were examined. The acute administration of very low doses of APO (30 .mu.g/kg; s.c.) reduces the behavioral deficits; a chronic administration of d-AMPH (2 injections daily for 43 days) reduces locomotor hyperactivity. In these 2 cases, the lesioned rats'' activity reaches the control level. DA-A10 neurons have a primary role in the VMT behavioral syndrome. Acute APO and chronic d-AMPH effects are discussed in terms of reactivation of DA postsynaptic receptors disafferented after DA-A10 group destruction and also strengthening of the hyperfunctioning of the remaining DA-A10 neurons. VMT-A10 syndrome could be a good animal model for pathophysiological studies. In humans, locomotor hyperactivity is dominant in manic syndrome in adults and hyperkinesis in children; both are reduced by drugs acting on DA synapses.