PRODYNORPHIN AND VASOPRESSIN MESSENGER-RNA LEVELS ARE DIFFERENTIALLY AFFECTED BY CHRONIC ETHANOL INGESTION IN THE MOUSE

Opioid peptides derived from the precursor, prodynorphin, are co-local ized with vasopressin in the hypothalamus and posterior pituitary, and vasopressin and prodynorphin synthesis are coordinately regulated dur ing salt-loading. We had previously found that chronic ethanol ingesti on resulted in decreased levels of hypothalamic and extrahypothalamic vasopressin mRNA, and the current study investigated the effect of eth anol ingestion on prodynorphin mRNA levels. A cRNA probe was construct ed from a PCR product amplified from mouse genomic DNA. Cloning and se quencing of the PCR product revealed that the sequence of the mouse pr odynorphin gene used to synthesize the probe is highly conserved, with high sequence similarity to corresponding regions of the gene in othe r mammalian species. In situ hybridization using the cRNA probe showed a widespread distribution of prodynorphin mRNA in mouse brain. In deh ydrated mice, prodynorphin mRNA was significantly increased in the hyp othalamus and nearly all other brain areas examined. In ethanol-fed mi ce, prodynorphin mRNA was also significantly increased in hypothalamus (50-60%) and in most brain areas. In the same mice, measurement of hy pothalamic vasopressin mRNA confirmed a significant (approximately 60% ) decrease. These results indicate that hypothalamic vasopressin and p rodynorphin mRNA can be differentially regulated in certain situations .