CHRONIC FOOD RESTRICTION ALTERS MU-OPIOID AND KAPPA-OPIOID RECEPTOR-BINDING IN THE PARABRACHIAL NUCLEUS OF THE RAT - A QUANTITATIVE AUTORADIOGRAPHIC STUDY

Using quantitative autoradiography, it was previously observed that ch ronic food restriction alters mu and kappa receptor binding in several regions of the rat forebrain. The present autoradiographic study was designed to investigate whether food restriction affects regional mu a nd kappa binding in the brainstem. [H-3]DAGO (mu) and mu/delta blocked [H-3]BMZ (kappa) binding were analyzed in 21 brainstem regions. A sig nficant decrease in mu binding was observed in the external lateral an d external medial subnuclei of the parabrachial nucleus while a signif icant increase in kappa binding was observed in the external lateral s ubnucleus. The possible functional significance of these changes is di scussed.