BRAIN MONOAMINES AND OPTOKINETIC PERFORMANCES IN PIGMENTED AND ALBINO-RATS

The aim of this study was two-fold: 1) To provide in DA-HAN rats the b asic brain monoamine data useful for later investigations of the neuro chemical effects of sensory alterations and 2) to assess whether there is a relationship between the monoaminergic pattern in medial vestibu lar nuclei and optokinetic performances. We comparatively studied the regional brain monoamine distribution and the optokinetic performances in pigmented DA-HAN and albino Sprague Dawley rats. As expected, the optokinetic responses and vestibuloocular reflex gain were by far more efficient in DA-HAN rats. Norepinephrine (NE), dopamine (DA), seroton in (5-HT) and their metabolites were determined in retina, brainstem n uclei and dopaminergic areas. DA-HAN rats exhibited an increased norad renergic activity in the medial vestibular nuclei, locus coeruleus and anteroventral cochlear nucleus, an extended decrease of serotonergic activity in brainstem nuclei and increased DA stores with a reduced do paminergic activity in most dopaminergic areas. These data confirm and extend the general findings that biochemical data obtained in one str ain cannot be extrapolated to another strain. The possible role of the morphological neuronal abnormalities and functional impairment induce d by albinism has been discussed especially in medial vestibular nucle us, cochlear nuclei and retina. Alternatively, behavioral factors may also explain some of the observed neurochemical differences. Copyright (C) 1997 Elsevier Science Inc.