Changes of mRNA expression of enkephalin and prodynorphin in hippocampus of rats with chronic immobilization stress.

Aim: To observe the changes of enkephalin mRNA and prodynorphin mRNA in hippocampus of rats induced by chronic immobilization stress.

Methods: Thirty rats were randomly divided into three groups of 10 each: the normal control group (group A), the group induced by chronic immobilization stress for 7 d (group B) and the group induced by chronic immobilization stress for 21 d (group C). The changes of the enkephalin mRNA and prodynorphin mRNA in the rat hippocampus were detected by reverse transcription-polymerase chain reaction (RT-PCR).

Results: Expression levels of enkephalin mRNA and prodynorphin mRNA in rat hippocampus were significantly increased under chronic immobilization stress, and the expression of prodynorphin mRNA in the rat hippocampus in group C was remarkably higher than that in group B (0.624 +/- 0.026; n = 5; P<0.01).

Conclusion: The increased enkephalin mRNA and prodynorphin mRNA gene expressions in rat hippocampus were involved in chronic stress.