GABA is secreted in all of the following sites except the (a) neuromuscular synapses, (b) hypothalamus, (c) Purkinje cells, (d) retina. 6. Endocannabinoids act throughout the CNS and are (a) excitatory, (b) involved in learning and memory, (c) first messengers, (d) water soluble. 7. Inhibition of acetylcholinesterase by poisoning blocks neurotransmission at the neuromuscular junction because (a) ACh is no longer released by the presynaptic terminal,
