| Abstract: | Cerebral metabolic patterns produced by different doses of the benzomorphan opioid drug,d-N-allylnormetazocine (d-NANM), were stud using the 2-deoxy-d-[1-14C]glucose method in rats. The lowest dose ofd-NANM (0.5 mg/kg) decreased regional cerebral metabolic rates for glucose (rCMRglc) in areas, such as cranial nerve nuclei, that contain high densities of sigma (σ) receptors. However, higher doses of the drug (2.7 and 5 mg/kg) increased rCMRglc in components of the extrapyramidal motor and limbic systems. Some of these latter areas (e.g. molecular layer of the dentate gyrus, accumbens nucleus, globus pallidus, ventral posterior nucleus of the thalamus) are not enriched in σ receptors. Reductions in rCMRglc produced by the lowerst dose ofd-NANM probably reflect direct interactions of the drug with σ receptors, whereas increases in rCMRglc observed with the highest doses more likely result from effects ofd-NANM on PCP receptors. |
