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Evidence for mu opioid receptor mediation of enkephalin-induced electroencephalographic seizures.
J Pharmacol Exp Ther. 1987 Feb; 240(2):571-7.JP

Abstract

The opioid receptor types involved in the mediation of enkephalin-induced electroencephalographic (EEG) seizures were studied in unanesthetized, freely moving rats. Four receptor-selective peptide ligands were evaluated for effectiveness in producing nonconvulsive EEG seizures after i.c.v. administration; these included the mu agonist, [D-Ala2-N-methyl-Phe4-Gly5-ol]enkephalin (DAGO), the mixed mu-delta agonist, [D-Ala2-D-Leu5]enkephalin (DADLE), and the selective delta agonists, [D-Pen2-D-Pen5]enkephalin and [D-Pen2-L-Pen5]enkephalin. Only DAGO and DADLE were found to produce EEG seizures, with DAGO being 9 times more potent than DADLE. DAGO produced a greater number of seizure episodes with a greater overall incidence compared with DADLE, reflecting its potent effect to elicit EEG seizure activity in these rats. Injections of [D-Pen2-D-Pen5]enkephalin or [D-Pen2-L-Pen5]enkephalin, even at the highest doses tested, failed to produce seizure activity. Behaviorally, the DAGO and DADLE EEG seizures were nonconvulsive but were temporally associated with episodic bursts of wet-dog shakes. The enkephalin-induced responses were extremely sensitive to antagonism by naloxone and completely blocked by pretreatment with the irreversible mu antagonist beta-funaltrexamine. The selective delta opioid receptor antagonist ICI 174,864 (N,N-diallyl-Tyr-Aib-Aib-Phe-Leu-OH) was ineffective. The use of the most selective agonists and antagonists for mu and delta opioid receptors suggests that, in rats, enkephalin-induced EEG seizures are mediated exclusively by mu opioid receptors and not by delta opioid systems.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

3027318

Citation

Tortella, F C., et al. "Evidence for Mu Opioid Receptor Mediation of Enkephalin-induced Electroencephalographic Seizures." The Journal of Pharmacology and Experimental Therapeutics, vol. 240, no. 2, 1987, pp. 571-7.
Tortella FC, Robles L, Mosberg HI. Evidence for mu opioid receptor mediation of enkephalin-induced electroencephalographic seizures. J Pharmacol Exp Ther. 1987;240(2):571-7.
Tortella, F. C., Robles, L., & Mosberg, H. I. (1987). Evidence for mu opioid receptor mediation of enkephalin-induced electroencephalographic seizures. The Journal of Pharmacology and Experimental Therapeutics, 240(2), 571-7.
Tortella FC, Robles L, Mosberg HI. Evidence for Mu Opioid Receptor Mediation of Enkephalin-induced Electroencephalographic Seizures. J Pharmacol Exp Ther. 1987;240(2):571-7. PubMed PMID: 3027318.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evidence for mu opioid receptor mediation of enkephalin-induced electroencephalographic seizures. AU - Tortella,F C, AU - Robles,L, AU - Mosberg,H I, PY - 1987/2/1/pubmed PY - 1987/2/1/medline PY - 1987/2/1/entrez SP - 571 EP - 7 JF - The Journal of pharmacology and experimental therapeutics JO - J Pharmacol Exp Ther VL - 240 IS - 2 N2 - The opioid receptor types involved in the mediation of enkephalin-induced electroencephalographic (EEG) seizures were studied in unanesthetized, freely moving rats. Four receptor-selective peptide ligands were evaluated for effectiveness in producing nonconvulsive EEG seizures after i.c.v. administration; these included the mu agonist, [D-Ala2-N-methyl-Phe4-Gly5-ol]enkephalin (DAGO), the mixed mu-delta agonist, [D-Ala2-D-Leu5]enkephalin (DADLE), and the selective delta agonists, [D-Pen2-D-Pen5]enkephalin and [D-Pen2-L-Pen5]enkephalin. Only DAGO and DADLE were found to produce EEG seizures, with DAGO being 9 times more potent than DADLE. DAGO produced a greater number of seizure episodes with a greater overall incidence compared with DADLE, reflecting its potent effect to elicit EEG seizure activity in these rats. Injections of [D-Pen2-D-Pen5]enkephalin or [D-Pen2-L-Pen5]enkephalin, even at the highest doses tested, failed to produce seizure activity. Behaviorally, the DAGO and DADLE EEG seizures were nonconvulsive but were temporally associated with episodic bursts of wet-dog shakes. The enkephalin-induced responses were extremely sensitive to antagonism by naloxone and completely blocked by pretreatment with the irreversible mu antagonist beta-funaltrexamine. The selective delta opioid receptor antagonist ICI 174,864 (N,N-diallyl-Tyr-Aib-Aib-Phe-Leu-OH) was ineffective. The use of the most selective agonists and antagonists for mu and delta opioid receptors suggests that, in rats, enkephalin-induced EEG seizures are mediated exclusively by mu opioid receptors and not by delta opioid systems. SN - 0022-3565 UR - https://www.unboundmedicine.com/medline/citation/3027318/Evidence_for_mu_opioid_receptor_mediation_of_enkephalin_induced_electroencephalographic_seizures_ DB - PRIME DP - Unbound Medicine ER -