Facilitation of neuroleptic-induced perioral movements in rats by hyperglycemia

Abstract

We have noted the emergence of spontaneous abnormal perioral movements 3-4 days following pinealectomy in drug-naive rats. The severity of these movements peaked at six weeks and then gradually attenuated over the following two months. This suggests that activation of neurochemical compensatory mechanisms may account for the diminution in the severity of perioral movements. Pinealectomy transiently increases plasma MSH levels, and the attenuation of perioral movements may have been associated with normalization of plasma MSH. We hypothesize that hypothalamic dysfunction of MSH-release inhibiting factor (MIF) may result in abnormal MSH levels and contribute to the persistence of tardive dyskinesia (TD) in patients. Since high levels of MSH may be associated with seborrhea, we examined the relation between TD and seborrhea in a schizophrenic patient with mild choreoathetoid movements of the orofacial and upper limb regions. He also had mild seborrheic lesions on the face and scalp. Worsening of TD following neuroleptic discontinuation was associated with marked exacerbation of seborrhea and appearance of extensive scalp dandruff. The simultaneous worsening of TD and seborrhea was reported to have occurred on multiple occasions previously. Neuroleptics increase plasma MSH levels. We propose that the presence of chronic seborrhea in patients receiving long-term neuroleptic treatment may indicate dysfunction of hypothalamic-pituitary regulation of MSH and herald the development of persistent TD.