Long-lasting hypersensitivity to methamphetamine following amygdaloid kindling in cats: the relationship between limbic epilepsy and the psychotic state.
This study attempts to analyze the biological mechanisms involved in the association of a psychotic state with temporal lobe epilepsy, and the inverse relation between the epilepsy and this psychotic state. Responses to a test dose of methamphetamine (MAP) were examined in amygdaloid-kindled cats. It was found that (i) MAP-induced stereotyped behavior was enhanced after amygdaloid kindling, and this hypersensitivity lasted for at least 10 days after the final convulsion, (ii) autonomic responses to MAP including piloerection, salivation, heart rate, and respiration rate were also enhanced by the kindling, (iii) kindled generalized convulsions were suppressed during MAP-induced stereotyped behavior in some cats, and (iv) this suppression was blocked by pretreatment with pimozide. Engel and Ackermann proposed that inhibitory events precipitated by each kindling stimulus could produce changes in the catecholaminergic system similar to the reverse tolerance seen with dopamine agonists, and that inhibitory hypersensitivity could parallel the development of kindled excitation. This was partially confirmed by the present study, and leads to the hypothesis that excitation of seizure-inhibiting activity, including activity of the dopamine system, may be related to the emergence of a psychotic state, and to the inverse relationship between epilepsy and the psychotic state in temporal lobe epilepsy.
D000679:Amygdala / Q000187:drug effects*; D000818:Animals; D001143:Arousal / Q000187:drug effects; D002352:Carrier Proteins; D002415:Cats; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007696:Kindling, Neurologic / Q000187:drug effects*; D008032:Limbic System / Q000187:drug effects*; D008694:Methamphetamine / Q000494:pharmacology*; D010863:Piloerection / Q000187:drug effects; D010868:Pimozide / Q000494:pharmacology; D011605:Psychoses, Substance-Induced / Q000209:etiology*; D011941:Receptors, Adrenergic / Q000187:drug effects; D012119:Respiration / Q000187:drug effects; D012472:Salivation / Q000187:drug effects; D012640:Seizures / Q000139:chemically induced*; D013239:Stereotyped Behavior / Q000187:drug effects
D002352:Carrier Proteins; D011941:Receptors, Adrenergic; C036062:amphetamine receptor; D010868:Pimozide; D008694:Methamphetamine