up: [[Neuron signaling]] Tags: # Autoreceptor system The ==autoreceptor== system is the main method through which neuron cells regulate neurotransmitter levels during [[Neuron signaling]]. They are receptors located in neurons that monitor neurotransmitter synthesis and/or release. Then, in response they regulate how much more neurotransmitter is released or synthesized. ### Examples One of the funniest examples is with caffeine. Caffeine works as an antagonist by turning off the autoreceptor effects of adenosine receptors that normally inhibits transmitter release. Once it's deactivated, more catecholamines enter the post synapse which we know are very excitatory leading to it's legendary energizing effect. ^587530 This is why caffeine should only be drunk at least an hour and a half after waking up. Any earlier and adenosine levels haven't gotten enough time to rise in level in the body yet. Instead, you will get a nice coffee coma in the afternoon.