The transmitter must be released from the presynaptic nerve concomitantly with presynaptic nerve activity. When applied experimentally to target cells, the effects of the putative transmitter must be identical to the effects of stimulating the presynaptic pathway. A neuromodulator is a chemical which does not by itself cause excitation or inhibition postsynaptically, but which influences the probability that a neurotransmitter released from the same cell will cause a post-synaptic response. A neurohormone is a substance released from a neuron which travels far beyond the synapse, ie into the blood, to influence the activity of distant targets. GABA, Glycine, Aspartate, Glutamate 3.
Enkephalins are the body's own morphine.
C. Considerable evidence indicates co-localization of multiple neurotransmitters in individual neurons 1. To Be Continued In the Next Lecture D. Examples of drug sensitive sites in synaptic transmission 1. Microtubules responsible for orthograde and retrograde transport of macromolecules between the soma and distal processes. Electrically conductive axonal membranes. Sites for active reuptake of released transmitters.