Bradycardia elicited by microinjections of nociceptin/orphanin FQ into the intermediolateral cell column at T1-T2 in the rat.
Microinjections (30 nl) of nociceptin/orphanin FQ (N/OFQ) into the intermediolateral cell column (IML) at T1 and T2 levels of the spinal cord elicited bradycardia. The decreases in HR were 12.3+/-2.9, 17.3+/-2.7, 26.7+/-3.1, and 18.6+/-3.4 beats/min in response to 0.075, 0.15, 0.62, and 1.25 mM concentrations, respectively. Maximally effective concentration of N/OFQ was 0.62 mM. No changes in BP were elicited by microinjections of N/OFQ into the IML at T1-T2. The bradycardic responses were completely blocked by prior microinjections of a N/OFQ receptor (NOP receptor) antagonist ([N-phe(1)]-nociceptin-(1-13)-NH(2), 9 mM) into the IML at T1-T2. Blockade of myocardial beta-1 adrenergic receptors also abolished the bradycardic responses elicited by microinjections of N/OFQ into the IML. It was concluded that activation of NOP receptors in right IML at T1-T2 by N/OFQ elicited bradycardic responses which were mediated via the sympathetic nervous system.
Chitravanshi
Vineet C
VC
Department of Neurological Surgery, MSB H-586, University of Medicine and Dentistry of New Jersey--New Jersey Medical School, 185 South Orange Ave., Newark, NJ 07103, USA.
Sapru
Hreday N
HN
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001262:Atenolol / Q000494:pharmacology; D001794:Blood Pressure / Q000502:physiology; D001919:Bradycardia / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D008297:Male; D008845:Microinjections; D009292:Narcotic Antagonists; D018847:Opioid Peptides / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*; D013904:Thoracic Vertebrae; D000094942:Nociceptin Receptor; D000097629:Nociceptin
D000319:Adrenergic beta-Antagonists; D001262:Atenolol; D009292:Narcotic Antagonists; D018847:Opioid Peptides; D011957:Receptors, Opioid; D000094942:Nociceptin Receptor; D000097629:Nociceptin; C000722285:Oprl1 protein, rat