Recent evidence supports an antagonistic interaction between cholecystokinin (CCK) and opiate peptides. The present study determined the effects of various levels of morphine treatment on hypothalamic levels of CCK as determined by radioimmunoassay. Acute treatment with morphine sulfate (10 mg/kg) or implantation of one morphine pellet (75 mg free base) increased levels of CCK in whole hypothalamus. Increased expossure to morphine by either chronic injections or implantation two pellets did not result in a further change in whole hypothalamic CCK levels. In samples dissected into hypothalamic subregions, the effect of morphine on CCK levels was localized to medial but not lateral or posterior regions. These experiments extend earlier in vitro findings and suggest that some of the physiological and behavioral effects of opiate peptides may result from modulation of endogenous CCK.
Bibliographical noteFunding Information:
Supported in part by RSA MH38894 and a Washington University/Monsanto Biomedical Research Grant (J. W. O.), NS 18667 and NS 18335 (M. C. B.), ES 07066 and a Biomedical Research Support Grant from Washington University (P. L. F.). The excellent secretarial assistance of S. Goodman and V. Trantanella is greatly appreciated.
- cholecystokinin radioimmunoassay
- in vivo