Botox (Botulin toxin) blocks release of ACh at NMJ • Act at presynaptic receptors to block or stimulate neurotransmitter release o Adenosine acts at presynaptic receptors to inhibit/block release of excitatory amino acids (like glutamate)…effect is blocked by caffeine  This is an example of disinhibition = removal of the inhibition Cholinergic ...