NOCICEPTIN AND ITS RECEPTOR IN GUINEA-PIG SYMPATHETIC-GANGLIA

The occurrence and distribution of nociceptin, a 17-amino acid peptide with structural similarity to dynorphin A, and its receptor, opioid r eceptor-like-1 (ORL1) receptor, were investigated in the guinea-pig sy mpathetic nervous system by means of immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR), respectively. Immuno fluorescence revealed varicose nociceptin-immunoreactive axons and som e paraganglionic cells in prevertebral (coeliaco-superior mesenteric, inferior mesenteric), but not in paravertebral (superior cervical, ste llate, lumbar chain) sympathetic ganglia. Messenger RNA for the ORL1 r eceptor, however, was detected by RT-PCR in both para-and prevertebral ganglia. The findings suggest participation of the nociceptin/ORL1 re ceptor signalling pathway in processing of information within preverte bral ganglia, and a general responsiveness of sympathetic neurons to n ociceptin. (C) 1997 Elsevier Science Ireland Ltd.