The Effects of Octopamine on the EPSPs of <em>Procambarus clarkii</em> are linked to IP₃ Receptors

Abstract

The neurotransmitter octopamine raises the amplitude of excitatory post-synaptic potentials (EPSP) in crayfish (Procambarus clarkii). Previous studies have ruled out a connection between octopamines effects and cAMP or cGMP systems, suggesting another secondary messenger system is responsible for the increase in EPSP amplitude. The IP₃ system, which is responsible for the release of intracellular calcium, has been suggested as a possible mechanism by which octopamines effects on EPSP are generated. Using intracellular recording, the EPSPs of crayfish in three different solutions were measured; a baseline ringers solution, a solution containing octopamine, and a solution containing octopamine and 2APB, an IP₃ receptor blocker. We found that the solution with the IP₃ receptor blocker had a much lower EPSP, supporting our hypothesis that octopamine acts via the IP₃ system.