Effects, in the rat, of various stressing procedures on the jaw-opening reflex induced by tooth-pulp stimulation.
Jaw-opening reflex (JOR) induced by a repetitive tooth-pulp stimulation delivered at 1 Hz was observed in awake, freely-moving rats. Modifications of the reflex responses of the digastric muscle were produced by foot-shock stimulation, by an oesophageal administration of placebo and a subcutaneous injection of saline. Subcutaneous injection of saline evoked a total disappearance of the reflex which returned within 30 s. Foot shock delivered for 10 s and repeated twice a minute for 30 min of intensity, just below the vocalization threshold, evoked a marked decrease of the reflex to 60 +/- 6 per cent of the control value (n = 10). Administration of arabic gum by oesophageal tube gave either: the same transient disappearance as for the subcutaneous injection in 6 rats; a progressive 28 min +/- 11 (n = 6) return to the initial value; a progressive return to a subcontrol value of 52 +/- 4 per cent (n = 7). The application of two successive stimuli resulted in a more pronounced JOR decrease. The response to electrical foot shock can be explained by a central analgesia induced by stress.
Vassel
A
A
Pajot
J
J
Aigouy
L
L
Rajaona
J
J
Woda
A
A
D000818:Animals; D003782:Dental Pulp / Q000503:physiopathology*; D004558:Electric Stimulation; D004597:Electroshock; D007568:Jaw / Q000503:physiopathology*; D008297:Male; D009119:Muscle Contraction; D010919:Placebos; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000187:drug effects; D012965:Sodium Chloride; D013312:Stress, Physiological / Q000503:physiopathology*
D010919:Placebos; D012965:Sodium Chloride