What effect will MAO inhibitors (MAOIs) have on synaptic norepinephrine levels?

Monoamine oxidase inhibitors will elevate the concentration of norepinephrine in the synapse.

Explanation: Monoamine oxidase is an enzyme that catalyzes the removal of monoamines such as norepinephrine, serotonin and dopamine from the brain. Monoamines are neurotransmitters involved in the transmission of nerve impulses in the brain. Monoamine oxidase inhibitors prevent the removal of these neurotransmitters thereby making them more available in the synapse. MAOIs inhibit the action of monoamine oxidase which catalyzes the removal of norepinephrine from the synapse thereby raising the level of norepinephrine in the synapse.

the first wave of extinction may be related to rapid cooling at the end of the Ordovician Period, and the second phase is widely regarded as having been caused by the sea-level fall associated with the glaciation.