Spinal beta-endorphin analgesia involves an interaction with local monoaminergic systems.

Spinal beta-endorphin analgesia involves an interaction with local monoaminergic systems.

Crisp T; Stafinsky J L; Hess J E; Uram M

European journal of pharmacology

1989

1989-01

beta-Endorphin administered intrathecally (i.t.) in rats produced a dose-dependent elevation in tail-flick latency. Naltrexone administered i.t. as a pretreatment reversed the spinal antinociceptive action of beta-endorphin, suggesting that the opioid interacts directly with spinal opiate receptors. Spinal administration of the alpha 1-adrenoceptor antagonist WB-4101 failed to alter the analgesic effects of the opioid, whereas the alpha 2-adrenoceptor antagonist yohimbine completely blocked beta-endorphin-induced elevations in tail-flick latency. Thus, there is an apparent specificity for the alpha

Male; Animals; Rats; Adrenergic alpha-Antagonists/pharmacology; Injections; Serotonin Antagonists/pharmacology; Naltrexone/pharmacology; Spinal Cord/*drug effects; Biogenic Monoamines/*physiology; Analgesics/administration & dosage/antagonists & inhibitors/*pharmacology; beta-Endorphin/administration & dosage/antagonists & inhibitors/*pharmacology; Norepinephrine/physiology; Serotonin/physiology; Inbred Strains; Spinal

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