Effect of reserpine treatment on enkephalin mRNA level in the rat striatum: an in situ hybridization study.

We investigated the molecular mechanisms responsible for the preproenkephalin A mRNA increase following catecholamine depletion by reserpine using quantitative in situ hybridization at the cellular level. Macroscopic analysis showed that short term reserpine treatment increases the preproenkephalin A mRNA level in the rat striatum to +40.2 +/- 9%. Microautoradiography analysis demonstrated different increases in the preproenkephalin A mRNA level in different parts of the striatum: +124 +/- 22% in the dorso-median striatum, +131 +/- 19% in the dorso-lateral striatum, +119 +/- 8% in the ventro-lateral striatum and +75 +/- 6% in the ventro-median striatum. We found no difference in the number of cells expressing PPA mRNA in reserpine treated rats suggesting that these increases are only due to an increase in the number of mRNA expressed by cell.