EFFECTS OF MORPHINE AND NALOXONE ON THE RESPONSIVENESS (UNIT AND FIELD POTENTIAL) OF 3 OPIATE-RELEVANT BRAIN-AREAS DURING ELECTRICAL-STIMULATION OF THE SUBSTANTIA-NIGRA | Academic Article individual record
abstract

1. 1. The study was conducted in 27 paralyzed and unanesthetized rats. 2. 2. In the pretreatment state, unit activity usually increased during 10/sec electrical stimulation of the substantia nigra in the three brain areas tested; responsiveness was greatest in the central grey, where there was also a clear intensity-response relation, and least in the amygdala. In all areas, the field potentials (EEG) associated with the unit responses were of the simple evoked-response type or augmenting (waxing and waning amplitude). 3. 3. Morphine (15 mg/kg, i.p.) generally depressed the evoked increases in unit activity in all areas. However, morphine enhanced evoked activity in a significant number of caudate and amygdala loci; but in the central grey, depression was more distinct and consistent (this even applies to spontaneous activity, except that morphine did excite 3 loci in 3 rats). Morphine decreased the amplitude of field potential responses to stimulation in the caudate and amygdala. Possible diurnal influences of morphine on both unit and field potential activity were tested for but not found. 4. 4. The administration of naloxone (1 mg/kg, i.p.) after morphine generally reversed the unit and field potential depression, but reversal was less consistent in the caudate. In neural populations where morphine enhanced unit activity, naloxone had no clear effect. Naloxone when given to saline-treated controls had no clear effect in any area. © 1980.

author list (cited authors)
KLEMM, W. R., & MALLARI, C. G.
publication date
1980
publisher
Elsevier bv Publisher
keywords
  • Electroencephalography
  • Naloxone
  • Male
  • Animals
  • Morphine
  • Female
  • Evoked Potentials
  • Receptors, Opioid
  • Action Potentials
  • Electric Stimulation
  • Caudate Nucleus
  • Amygdala
  • Rats
  • Substantia Nigra
citation count

3