Release of alpha-neoendorphin from the anterior pituitary gland of conscious rats

Modification of acetylcholine release by nociceptin in conscious rat striatum

Nociceptin (NOC), an endogenous ligand for the orphan opioid receptor ORL1 (ORL1), has recently been recognized as a neuropeptide. We used brain microdialysis and on-line high performance liquid chromatography (HPLC) to examine the effect of NOC on the basal outflow of acetylcholine (ACh) in the freely moving rat striatum in vivo. ACh release was reduced by nociceptin at a concentration of 10(-5) M to 79% of control release. This effect of NOC was attenuated by [Phe1Psi(CH2-NH)Gly2]nociceptin-(1-13)-NH2 (PhePsi), suggesting that NOC activates the ORL1 receptor and (PhePsi) acts as an antagonist on ORL1 in rat striatum in vivo. These findings indicate that NOC may act as a neuropeptide which inhibits ACh release in the striatum via ORL1.

Modification of dopamine release by nociceptin in conscious rat striatum

Nociceptin (NOC), an endogenous ligand for the orphan receptor ORL1, has recently been recognized as a neuropeptide. We used brain microdialysis and on-line high performance liquid chromatography to examine the effect of NOC on the basal outflow of dopamine (DA) and its metabolite in the freely moving rat striatum in vivo. The percent change of DA release induced by NOC at concentrations of 10-6 and 10-5 M were 383% and 398%, respectively. This effect of NOC was attenuated by naloxone, suggesting that NOC activates classic (micro, delta, kappa) receptors in a very little way. These data indicates that NOC may act as a neuropeptide which enhances DA release from the striatum of rat brain via an opioid receptor.

Endogenous opiates: 1994

This article is the 17th installment of our annual review of research concerning the opiate system. It includes papers published during 1994 involving the behavioral, nonanalgesic, effects of the endogenous opiate peptides. The specific topics covered this year include stress; tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.