Patterns of Purinergic Modulation of Myoneural Transmission in Presence of Capsaicin

Abstract

This study aimed to investigate myoneural transmission in the presence of capsaicin, which acts as an integrator of pain stimuli and causes heat sensation. The effects of purines that participate in synaptic transmission, such as ATP and adenosine, in the presence of capsaicin were explored. When the neuromuscular preparation of frog was perfused with solution containing capsaicin, the inhibitory effects of both purines were significantly reduced. A reduction of the depressant effects of adenosine is associated with the inhibition of A₁ signaling, since the A_2A receptor agonist CGS21680 showed a pronounced potentiating effect in the presence of capsaicin, which was almost completely hidden in the control. Our findings suggest that the known neuroprotective effect of capsaicin is primarily due to elimination of inhibition by endogenous purines of the induced quantum output of the neurotransmitter.