Effects of 3,4‐methylenedioxymethamphetamine (‘Ecstasy’) on the jaw‐opening reflex and on the α₂‐adrenoceptors which regulate this reflex in the anesthetized rat

Abstract

Bruxism, principally jaw clenching, is frequently observed in users of the recreational drug 3,4-methylenedioxymethamphetamine (MDMA). It has been suggested that during bruxism a reduction of the activity of oral protective reflexes occurs. In this study we investigated the effects of intravenously administered MDMA on the digastric electromyographic responses elicited by orofacial electrical stimulation in the rat. We also assessed the effects of either the administration of a single dose (20 mg kg(-1), s.c.) or repeated doses of MDMA (same dose, twice a day, for 4 d) on the jaw-opening reflex (JOR) and on the sensitivity of the alpha(2)-adrenoceptors which, in an inhibitory way, regulate it. Increasing doses of MDMA (1-29440 micro g kg(-1)) induced an incomplete inhibition of JOR and 50% inhibition (ED(50)) at 2550 micro g kg(-1); maximal inhibition was 88%. The repeated treatment with MDMA led to an enhancement of the inhibition of JOR induced by the alpha(2)-agonist, clonidine (ED(50) was reduced by 77%), indicating an increased sensitivity of the alpha(2)-adrenoceptors. This study shows that the intravenous administration of MDMA reduces the JOR while repeated doses of the drug enhance the inhibitory noradrenergic mechanisms which regulate the reflex. The results also allow speculation that a reduction of JOR may underlie the occurrence of episodes of bruxism in MDMA users.

Ecstasy (MDMA) and oral health

“…33 Although these results cannot directly be extrapolated to man, they are in line with the frequently reported jaw clenching and grinding of teeth during ecstasy use (50-89%).…”

Effects of MDMA, MDA and MDEA on blood pressure, heart rate, locomotor activity and body temperature in the rat involve α‐adrenoceptors

“…Ingestion of amphetamine derivatives has been associated with acute adverse reactions such as hyperthermia, hypertension, tachycardia, acute myocardial infarction and increased motor activities such as jaw clenching ( Hegadoren et al ., 1999 ; Cole & Sumnall, 2003a ). Consistent with clinical signs, animal studies have also shown increases in blood pressure, disruption in thermoregulation, inhibition of the jaw opening reflex and increased locomotor activity ( Gold et al ., 1988 ; Colado et al ., 1995 ; 1999 ; Daws et al ., 2000 ; Boules et al ., 2001 ; Arrue et al ., 2004 ). Furthermore, it has been demonstrated that repeated treatment with amphetamines in experimental animals can produce either tolerance or sensitization to their behavioural actions ( Foltin & Schuster, 1982 ; Kalivas et al ., 1998 ).…”

“…Urinary retention reported with MDMA ( McCann et al ., 1996 ) may also involve peripheral α ‐adrenoceptor‐mediated actions. The jaw clenching reported with the use of MDMA ( Hayner & McKinney, 1986 ; McCann et al ., 1996 ) may involve α 2 ‐adrenoceptor‐mediated inhibition of the jaw opening reflex ( Arrue et al ., 2004 ), presumably by a central action. Acute psychiatric complications of MDMA, including panic attacks ( McCann et al ., 1996 ), as well as temperature changes ( Bexis & Docherty, 2005 ), may also involve noradrenergic mechanisms.…”

Bruxism: its multiple causes and its effects on dental implants – an updated review*

“…Also, the amphetamine‐like substance XTC reportedly has bruxism as a side effect (47). Based on a study with rats, Arrue et al (48) give a possible explanation for this side effect of XTC, viz. the XTC‐induced reduction of the jaw‐opening reflex.…”