EFFECTS OF ANESTHETICS AND ELECTRICAL-STIMULATION ON NIGROSTRIATAL DOPAMINERGIC-NEURONS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 224  (3) , 489-493
Abstract
Induction of anesthesia with pentobarbital (40 mg/kg), urethane (1.8 g/kg), chloral hydrate (400 mg/kg) or ketamine (150 mg/kg) followed by a 20-min sham implantation of a bipolar electrode in substantia nigra fibers [rat] caused a marked, ipsilateral increase in caudate dihydroxyphenylacetic acid (DOPAC). No sham stimulation was found after .gamma.-butyrolactone (500 mg/kg) anesthesia or in a paralyzed, artificially respired preparation. By using .gamma.-butyrolactone anesthesia, the nigrostriatal fibers were electrically stimulated (25 Hz, 1.5 ms duration) at differing current intensities (40, 80, 100, 120 and 180 .mu.A). The maximum increase in caudate DOPAC occurred at 120 .mu.A. Electrical stimulation (100 .mu.A, 25 Hz, 1.5 ms duration) in the paralyzed preparation yielded similar increases in caudate DOPAC. By using a 50% effective current (100 .mu.A), variation of the frequency (5, 10, 25 and 125 Hz) produced a maximum in caudate DOPAC at 10 Hz. These data reveal an interaction between many anesthetics and physical disruption of dopaminergic neurons, as well as provide an in vivo model of stimulus-dependent dopamine release.