Inhibitory Postsynaptic Potential - Inhibitory Molecules

Inhibitory Molecules

GABA is a very common neurotransmitter used in IPSPs in the adult mammalian brain and retina. GABA receptors are pentamers most commonly composed of three different subunits (α, β, γ), although several other subunits (δ,ε, θ, π, ρ) and conformations exists. The open channels are selectively permeable to chloride or potassium ions (depending on the type of receptor) and allow these ions to pass through the membrane. If the electrochemical potential of the ion is more negative than that of the action potential threshold then the resultant conductance change that occurs due to GABA binding to its receptors keeps the postsynaptic potential more negative than the threshold and decreases the probability of the postsynaptic neuron completing an action potential. Glycine molecules and receptors work much in the same way in the spinal cord, brain, and retina.