The descending pain modulatory pathway exerts bidirectional control of ongoing nociceptive inputs traveling from the body to the brain. Despite a large body of work implicating the vlPAG in pain modulation, the neuron type specific activation by acute and persistent inflammation has not been identified. This hypothesis posits selective MOR expression on GABAergic interneurons, however, several studies have revealed less targeted MOR expression, prompting us to determine whether MOR expression maps onto physiologically distinct neuron types.