title: Microdialysis reveals changes in extracellular opioid peptide levels in the amygdala induced by amygdaloid kindling stimulation.
abstract: Enkephalins released in basolateral nucleus of the amygdala in response to electrical stimulation were determined in amygdala kindled and nonkindled freely moving rats using microdialysis. Enkephalin release was enhanced after a single and repetitive electrical stimulation (233 and 130% above control levels, respectively) in nonkindled rats. In fully kindled rats, the extracellular enkephalin levels decreased (35% below the control levels) within the first 20 min after onset of stage V kindled seizures, reaching baseline level 40 to 60 min following the generalized seizure activity. HPLC analysis identified the majority of recovered immunoreactive material from the amygdala as Met-enkephalin. On the basis of our results it is suggested that the enhanced enkephalin release in the amygdala during the early kindling stages might have a suppressive effect which may represent a homeostatic mechanism to avoid the spread of the afterdischarge to other structures. The decreased extracellular level of enkephalin in the amygdala after stage V kindled seizures could reflect a general impairment of inhibitory mechanisms in this structure with subsequent production of seizure activity.
authors.affiliation: Department of Neurology, University of California at Los Angeles.
authors.forename: L
authors.initials: L
authors.lastname: Rocha
authors.forename: N T
authors.initials: NT
authors.lastname: Maidment
authors.forename: C J
authors.initials: CJ
authors.lastname: Evans
authors.forename: R F
authors.initials: RF
authors.lastname: Ackermann
authors.forename: J
authors.initials: J
authors.lastname: Engel
mesh_terms: D000679:Amygdala / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004558:Electric Stimulation; D004569:Electroencephalography; D004745:Enkephalins / Q000378:metabolism*; D007696:Kindling, Neurologic; D007700:Kinetics; D008297:Male; D017551:Microdialysis / Q000379:methods; D011188:Potassium / Q000494:pharmacology; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000378:metabolism; D013997:Time Factors
chemical_list: D004745:Enkephalins; D011188:Potassium