Blockade of opioid receptors in rostral ventral medulla prevents antihyperalgesia produced by transcutaneous electrical nerve stimulation (TENS)

A Kalra; M O Urban; K A Sluka

doi:10.1016/S0022-3565(24)29376-9

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Blockade of opioid receptors in rostral ventral medulla prevents antihyperalgesia produced by transcutaneous electrical nerve stimulation (TENS)

Journal article

Peer reviewed

Blockade of opioid receptors in rostral ventral medulla prevents antihyperalgesia produced by transcutaneous electrical nerve stimulation (TENS)

A Kalra, M O Urban and K A Sluka

The Journal of pharmacology and experimental therapeutics, Vol.298(1), pp.257-263

07/2001

DOI: 10.1016/S0022-3565(24)29376-9

PMID: 11408550

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Abstract

Although transcutaneous electrical nerve stimulation (TENS) is used extensively in inflammatory joint conditions such as arthritis, the underlying mechanisms are unclear. This study aims to demonstrate an opiate-mediated activation of descending inhibitory pathways from the rostral ventral medulla (RVM) in the antihyperalgesia produced by low- (4 Hz) or high-frequency (100 Hz) TENS. Paw withdrawal latency to radiant heat, as an index of secondary hyperalgesia, was recorded before and after knee joint inflammation (induced by intra-articular injection of 3% kaolin and carrageenan) and after TENS/no TENS coadministered with naloxone (20 microg/1 microl), naltrindole (5 microg/1 microl), or vehicle (1 microl) microinjected into the RVM. The selectivity of naloxone and naltrindole doses was tested against the mu-opioid receptor agonist [D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin (DAMGO) (20 ng, 1 microl) and the delta2-opioid receptor agonist deltorphin (5 microg, 1 microl) in the RVM. Naloxone microinjection into the RVM blocks the antihyperalgesia produced by low frequency (p < 0.001), but not that produced by high-frequency TENS (p > 0.05). In contrast, naltrindole injection into the RVM blocks the antihyperalgesia produced by high-frequency (p < 0.05), but not low-frequency (p > 0.05) TENS. The analgesia produced by DAMGO and deltorphin is selectively blocked by naloxone (p < 0.05) and naltrindole (p < 0.05), respectively. Thus, the dose of naloxone and naltrindole used in the current study blocks mu- and delta-opioid receptors, respectively. Hence, low-frequency and high-frequency TENS produces antihyperalgesia by activation of mu- and delta-opioid receptors, respectively, in the RVM.

Hyperalgesia - chemically induced

Naltrexone - analogs & derivatives

Transcutaneous Electric Nerve Stimulation

Enkephalin, Ala-MePhe-Gly- - pharmacology

Medulla Oblongata - drug effects

Receptors, Opioid, mu - drug effects

Analgesics, Opioid - pharmacology

Rats

Male

Pain Measurement - drug effects

Hot Temperature

Receptors, Opioid, delta - drug effects

Rats, Sprague-Dawley

Receptors, Opioid - physiology

Naltrexone - pharmacology

Animals

Hyperalgesia - therapy

Naloxone - pharmacology

Narcotic Antagonists - pharmacology

Oligopeptides - pharmacology

Medulla Oblongata - physiology

Receptors, Opioid - drug effects

Receptors, Opioid, delta - physiology

Receptors, Opioid, mu - physiology

Details

Title: Subtitle: Blockade of opioid receptors in rostral ventral medulla prevents antihyperalgesia produced by transcutaneous electrical nerve stimulation (TENS)
Creators: A Kalra - Physical Therapy Graduate Program, College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
M O Urban
K A Sluka
Resource Type: Journal article
Publication Details: The Journal of pharmacology and experimental therapeutics, Vol.298(1), pp.257-263
Publisher: United States
DOI: 10.1016/S0022-3565(24)29376-9
PMID: 11408550
ISSN: 0022-3565
eISSN: 1521-0103
Language: English
Date published: 07/2001
Academic Unit: Iowa Neuroscience Institute; Nursing; Physical Therapy and Rehabilitation Science; Neuroscience and Pharmacology
Record Identifier: 9984040241702771

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