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Electroacupuncture accelerates the biogenesis of central enkephalins in the rat

Yuan He, Han Jisheng

Department of Physiology, Beijing Medical College. Beijing, China

Abstract

Radioirr n:unoassay was used to determine the immunoreactive met-enkephalin and leu-enkephalin (Ir-MEK, Ir-LEK) contents in discrete brain areas, including striatum, hypothalamus, thalamus and pons-medulla of the rat. Intracerebroventricular (icv) injection of aminopeptidase inhibitor bestatin (B) or “enkephalinase” inhibitor thiorphan (T), 50 #mu#g each, had no significant influence on the cerebral contents of ir-enkephalins. Combined use of B&T elicited only a moderate increase of Ir-MEK in hypothalamus, suggesting that the turnover rate of cerebral tnkephalins was rather low when the rat was kept in a relatively quiescent condition. Electroacupuncture for 30 min increased the Ir-MEK and Ir-LEK contents both in striatum and hypothalamus by 40% (33-52%, P<0.O1). In rats given icv injection of B & T, 100 #mu#g each, and ip injection of a non-specific peptidase inhibitor D-phenylalanine (DPA), electroacupuncture (30 min) increased the Ir-MEK and Ir-LEK contents in striatum and hypothalamus by 120% (94-147%, P<0.01) . The results indicate that electroacupuncture stimulation accelerated biogenesis as well as release of enkephalins from neurons located in striatum and hypothalamus. Increase in steady state enkephalin content in brain tissues after EA stimulation suggests that the increased release of enkephalins. was compensated and even overstocked by accelerated biogenesis. The exact mechanisms of the increased production of enkephalins within a limited period of 30 min remain to be clarified. The fact that increase in cerebral enkephalin content was accompanied by an augmentation of electroacupuncture analgesia suggested that accumulated enkephadins protected by peptidase inhibitors may play a functional role in antinociception.

Key words: Enkephalins;Radioinmunoassay;Bestatin;Thiorphan;D-phenylalanine;Electroacupuncture analgesia

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Citing This Article：

Yuan He, Han Jisheng. Electroacupuncture accelerates the biogenesis of central enkephalins in the rat. Acta Physiol Sin 1985; 37 (3): (in Chinese with English abstract).