Single and repeated electroconvulsive shock differentially affects the prodynorphin and pro-opiomelanocortin system in the rat.
The effects of single and repeated maximal electroconvulsive shock (ECS, 150 mA, 50 Hz, 0.5 s) on the immunoreactive (ir-) dynorphin and beta-endorphin level in the rat brain, spinal cord and pituitary were studied. A single ECS induced a transient decrease in the hypothalamic ir-dynorphin, but did not influence the peptide content in the spinal cord, hippocampus and neurointermediate lobe of the pituitary. In contrast, the single ECS only slightly decreased the ir-beta-endorphin level in the hypothalamus, but caused a considerable fall in the peptide content in both lobes of the pituitary. A repeated ECS (every day for 9 days and 3 times a week for 3 weeks) markedly increased the ir-dynorphin content in the hypothalamus by 28 and 56%, respectively. Irrespective of the paradigm used, the repeated ECS strongly influenced spinal dynorphin neurons. At the beginning of our experiment (ECS applied 3 times) a fall in the peptide levels could be observed, but a longer treatment (ECS applied 9 times) led to its enhancement. The repeated ECS also induced a gradual decrease in the hippocampal ir-dynorphin level, followed by a long-term, rebound increase. In contrast to those numerous changes evoked in the dynorphin system, the repeated ECS did not evoke any changes in the hypothalamic and pituitary ir-beta-endorphin levels. As shown in the behavioral experiment, an acute ECS treatment resulted in a moderate increase in the pain threshold, measured by tail-flick and hot-plate tests. A prolonged ECS administration (3, 6 and 9 times) markedly enhanced the ECS-induced analgesia and catalepsy.(ABSTRACT TRUNCATED AT 250 WORDS)
D000698:Analgesia; D000818:Animals; D001923:Brain Chemistry; D002375:Catalepsy / Q000209:etiology; D004565:Electroconvulsive Therapy / Q000009:adverse effects; D004723:Endorphins / Q000378:metabolism; D004745:Enkephalins / Q000378:metabolism*; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism*; D011333:Pro-Opiomelanocortin / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000378:metabolism*; D013997:Time Factors; D001615:beta-Endorphin
D004723:Endorphins; D004745:Enkephalins; D011498:Protein Precursors; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; C033660:preproenkephalin