A given receptor can act as either an autoreceptor or a heteroreceptor, depending upon the type of transmitter released by the cell on which it is embedded.
In which respective drugs act are Clonidine on alpha 2 as Agonist used in hypertension which reduce release of norepinephrine and epinephrine from presynaptic neurons.
An atypical example is given by the β-adrenergic autoreceptor in the sympathetic peripheral nervous system, which acts to increase transmitter release.
Through a series of phosphorylation events related to PKA and PKC, active TAAR1 inactivates DAT, preventing uptake of dopamine from the synapse.
[citation needed] A feedback cell is activated by the (partially) depolarized post-synaptic neuron.
These changes in ion concentration effectively diminish the amount of the original neurotransmitter released by the presynaptic terminal into the synaptic cleft.