Chronic food restriction alters μ and κ opioid receptor binding in the parabrachial nucleus of the rat: a quantitative autoradiographic study

Abstract Using quantitative autoradiography, it was previously observed that chronic food restriction alters μ and κ receptor binding in several regions of the rat forebrain. The present autoradiographic study was designed to investigate whether food restriction affects regional μ and κ binding in the brainstem. [ 3 H]DAGO (It,) and μ/δ blocked [ 3 H]BMZ (κ) binding were analyzed in 21 brainstem regions. A signficant decrease in μ binding was observed in the external lateral and external medial subnuclei of the parabrachial nucleus while a significant increase in κ binding was observed in the external lateral subnucleus. The possible functional significance of these changes is discussed.