EXPRESSION PATTERNS AND DEPRIVATION EFFECTS ON GABA(A) RECEPTOR SUBUNIT AND GAD MESSENGER-RNAS IN MONKEY LATERAL GENICULATE-NUCLEUS

The expression and regulation of seven GABAA receptor subunit gene tra nscripts were examined in the adult monkey lateral geniculate nucleus. In situ hybridization histochemistry was used to localize mRNAs of th e genes encoding monkey-specific alpha 1, alpha 2, alpha 4, alpha 5, b eta 1, beta 2, and gamma 2 subunits. The highest levels of expression in the nucleus were for alpha 1, beta 2, and gamma 2 subunit transcrip ts. The levels were substantially higher in the magnocellular than in the parvocellular layers. Alpha-2, alpha 4, alpha 5, and beta 1 subuni t mRNAs were expressed at much lower levels, and magno- and parvocellu lar layers had approximately equal levels of expression. Following 4- or 21-day periods of monocular deprivation induced by intravitreal inj ections of tetrodotoxin, levels of the alpha 1, alpha 2, alpha 4, alph a 5, beta 1, and beta 2 mRNAs were decreased in the deprived geniculat e laminae. Adjacent sections hybridized with probes specific for 67-kD a glutamic acid decarboxylase (GAD) mRNA also showed decreased levels of expression in deprived laminae after the 21-day deprivation period. Levels of gamma 2 receptor subunit mRNA were unaffected by monocular deprivation. In our previous studies, a clearly significant downregula tion is observed for this subunit transcript in the visual cortex of m onkeys deprived for equivalent times. The differential expression and responses to deprivation in the lateral geniculate nucleus suggest reg ion-specific regulation of GABAA receptor subunit genes. (C) 1995 Wile y-Liss, Inc.