Modulation of Neurotransmitter Release by Carbon Monoxide at the Frog Neuro-Muscular Junction

Title: Modulation of Neurotransmitter Release by Carbon Monoxide at the Frog Neuro-Muscular Junction

Volume: 8 Issue: 2

Author(s): Guzel F. Sitdikova, Rustem R. Islamov, Marat A. Mukhamedyarov, Vladlena V. Permyakova, Andrey L. Zefirov and Andras Palotas

Affiliation:

Keywords: Acetyl-choline, cAMP, carbon monoxide, evoked acetyl-choline release, heme-oxygenase 2, neuro-muscular junction

Abstract: Carbon monoxide (CO) is an endogenous gaseous messenger, which regulates numerous physiological functions in a wide variety of tissues. Using extracellular microelectrode recording from frog neuro-muscular preparation the mechanisms of exogenous and endogenous CO action on evoked quantal acetyl-choline (Ach) release were studied. It was shown that CO application increases Ach-release in dose-dependent manner without changes in pre-synaptic Na+ and K+ currents. The effect of exogenous CO on Ach-release was decreased by prior application of guanylate cyclase inhibitor ODQ and prevented by application of a cyclic guanylate monophospate (cGMP) analog 8Br-cGMP. Pre-treatment of the preparation with adenylate cyclase inhibitor MDL-12330A has completely abolished the effect of CO, whereas elevation of intracellular level of cyclic adenosine monophospate (cAMP) mimicked and eliminated CO action. Application of cGMP-activated phosphodiestherase-2 inhibitor EHNA did not prevent CO action, whereas inhibition of cGMP-inhibited phosphodiestherase-3 by quazinone has partially blocked the effect of CO. Utilizing immuno-histochemical methods COproducing enzyme heme-oxygenase-2 (HO-2) was shown to be expressed in skeletal muscle fibers, mostly in subsarcolemmal region, karyolemma and sarcoplasmic reticulum. Zn-protoporphirin-IX, the selective HO-2 blocker, has depressed Ach-release, suggesting the tonic activating effect of endogenous CO on pre-synaptic function. These results suggest that facilitatory effect of CO on Ach-release is mediated by elevation of intracellular cAMP level due to activation of adenylate cyclase and decrease of cAMP breakdown. As such, endogenous skeletal muscle-derived CO mediates tonic retrograde up-regulation of neuro-transmitter release at the frog neuro-muscular junction.

Cite this article as:

Sitdikova F. Guzel, Islamov R. Rustem, Mukhamedyarov A. Marat, Permyakova V. Vladlena, Zefirov L. Andrey and Palotas Andras, Modulation of Neurotransmitter Release by Carbon Monoxide at the Frog Neuro-Muscular Junction, Current Drug Metabolism 2007; 8 (2) . https://dx.doi.org/10.2174/138920007779815940