The effects of κ-opioid agonist treatment on prodynorphin mRNA expression in the rat brain were studied. Rats were treated with the selective κ-opioid agonist U-69593 or vehicle for 5 days and prodynorphin mRNA was measured on day 8 (3 days after the last injection) or 22 (17 days after the last injection). On day 8 prodynorphin mRNA was increased in the hypothalamus and decreased in the striatum, frontal cortex, and hippocampus of rats treated with U-69593. On day 22, prodynorphin mRNA was increased in the hypothalamus, frontal cortex and striatum of U-69593 treated rats. These findings suggests that κ-opioid receptor agonist treatment has long-term, continually changing effects on prodynorphin mRNA expression.
- κ-Opioid receptor
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