Veterinary Neuropharmacology

RECEPTOR EVENTS

• After rapid migration of neurotransmitter across the cleft, the mediator substance bind with the receptive areas on the pre or postsynaptic membrane.
• Receptor events caused by interaction of transmitter substance with the receptor may be of two general types, excitatory or inhibitory.
• In excitatory response (EPSP-Excitatory post synaptic potential), there is a sudden depolarization of post synaptic membrane characterized by the net inward movement of  sodium and eflux of potassium ions along their respective concentration gradient.
• An (IPSP-inhibitory post synaptic potential) occurs when the neurotransmitter initiates a selective increase in permeability of the post synaptic membrane to only smaller ions (eg: K⁺, Cl^-).  The resulting hyperpolarization increases the threshold to stimuli and in effect elicits an inhibitory response to the cell.