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Hot plate versus tail flick: Evaluation of acute tolerance to continuous morphine infusion in the rat model

Year: 1995

Type: article

Abstract: The development of tolerance to continuous morphine infusion (2, 4 and 6 mg x kg(-1) x hr(-1) was assessed in rats using two different methods for evaluation of nociception, tail flick (TF) and hot plate (HP). The influence of repeated testing on nociception was evaluated using two regimens; series 1 was tested repeatedly 1, 2, 4, 6, and 8 hr after initiating the morphine infusion and series 2 was tested only twice, at maximum morphine effect and at 8 hr. Both, TF and HP showed pain threshold elevation after the morphine administration of 4 or 6 mg x kg(-1) x hr(-1), which reached a maximum at 2 hr after the start of the infusion. HP: reduction of the effect was found in group 4 mg x kg(-1) x hr(-1) in the series subjected to repeated testing; group 6 mg x kg(-1) x hr(-1) showed reduced effect in both sides. TF: the response latencies did not show reduction at 8 hr. Since TF is predominantly a spinal response and HP is predominantly supraspinal, the results suggest that tolerance during the first 8 hr of morphine infusion develops mainly at supraspinal level.

Source: Journal of Pharmacological and Toxicological Methods

DOI: 10.1016/1056-8719(94)00077-h

Authors: Lev Langerman, Mark I. Zakowski, Boris Piskoun, Gilbert J. Grant

Institutions: NYU Langone Health, New York University

Language: English

Topic: Pain Mechanisms and Treatments

Subfield: Physiology

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $3,500