Résumé
The limbic system has been implicated in the modulation of pain. The aim of this study was to determine the role of amygdala in different types of pain, viz., phasic and tonic. Unilateral stimulation of central nucleus of amygdala (CeA), basolateral nucleus (BL) and medial amygdaloid (MeA) in conscious rats resulted in the reduction of the tonic formalin-induced pain. The thresholds for simple vocalization (SV) and vocalization after-discharge (VA) were elevated during amygdalar stimulation in the tail-flick (phasic pain) test. However, the threshold for tail-flick (TF) evoked by electric shock was not affected. Tail-flick latency (TFL) to noxious heat was accentuated during amygdalar stimulation. These results suggest that amygdala had a modulatory role in the descending endogenous pain control mechanisms.
Sujets)
Amygdale (système limbique)/anatomie et histologie , Animaux , Stimulation électrique , Émotions/physiologie , Formaldéhyde/diagnostic , Mâle , Douleur/physiopathologie , Mesure de la douleur , Seuil nociceptif/physiologie , Rats , Temps de réaction/physiologie , Vocalisation animale/effets des médicaments et des substances chimiquesRésumé
Pain thresholds were recorded in rats by progressive increase in electrical stimulation to induce tail withdrawal, vocalisation and vocalisation after discharge. It was observed that castration resulted in significant reduction of pain threshold which however returned to normal level on substitution with testosterone therapy.