Can exogenous administrated neurotransmitters mediate transmission from one neuron to another? Thanks. (you may say, why not? but I want to know if I am right or wrong from experts.)
Depends on the neurotransmitter. Exogenous serotonin, dopamine, tyramine, and histamine can drive specific behavior phenotypes, and receptor mutants eliminate signaling and the behavioral effects. My understanding is that exogenous GABA, ACh, and glutamate do not work well. Drugs like muscimol and carbachol can drive behavior consequences similar to what would be expected, and these are typically lost in receptor mutants.
Exogenous bioamines are effective at inducing responses, but what I can’t recall offhand is whether they’ve been used in rescue experiments, that might show the exogenously supplied transmitter is being used in neuronal signaling rather than merely acting directly on target cells. For example, whether you can soak a cat-2 mutant in dopamine, let it recover, and then see if the animal now shows dopamine-dependent behavior.
My feeling is that exogenous dopamine and serotonin can rescue the respective biosynthetic mutants. I think that was shown in the Sawin Neuron paper from 2000. It’s a neat trick, but I don’t think it’s been used for other biosynthetic mutants.
Yeah, you’re right, I just checked and dopamine rescue of cat-2(lf) is in Sawin. I should have remembered that (or checked).