Biological indications of a novel "short" µ opiate receptor in domestic chicken.

Previous work from our laboratory has established that cellular signaling processes of endogenous morphine are mediated by cognate G protein coupled receptor (GPCR) proteins, designated µ(3) and µ(4) opiate receptors. µ(3) and µ(4) opiate receptors are structurally unique "short" 6 transmembrane helical (TMH) domain GPCRs that are selectively responsive to endogenous morphine, not to families of endogenous opioid peptides, and are uniquely coupled to activation of constitutive nitric oxide synthase (cNOS). Based on high resolution predictive measures, it appears likely that domestic poultry express a µ opiate receptor mRNA encoding potentially two novel GPCRs with similar biochemical characteristics as described for µ(3) and µ(4) opiate receptors as well as traditional µ(1) opioid receptors.

Cholinergic regulation of endogenous morphine release from lobster nerve cord.

Background: Invertebrate nervous systems are regulated by G-coupled protein receptors, chemical transporters, and ion channels responsive to established drugs of abuse including opiates, alcohol, psychostinulants, and nicotine. Thus, invertebrate nervous tissue preparations can be used as predictive model systems by which to evaluate underlying pharmacological mechanisms of addictive processes.

Material/methods: Ex vivo pharmacological trials were used to determine the comparative effects of the nicotinic agonists and antagonists on the evoked release of labeled morphine from H.