Purinergic signalling in sensory systems

Extracellular purines play multiple roles in a variety of sensory systems acting as neural signalling and humoral factors via purinoceptors. For example, ATP and adenosine have a neurosignalling role in autonomic sensory–motor reflexes, mechanoreception and chemoreception mediated via vagus nerve afferents, and in nociception. Purinergic neuromodulation of vision via adenosine in the retina is well established and there is mounting evidence for a neuromodulatory role for ATP in the inner ear. Humoral purinergic actions are found in the eye where adenosine clearly has an important vascular and humoral influence and in the inner ear where ATP probably regulates fluid homeostasis, hearing sensitivity and development. Clearly purinergic signalling underpins the physiology of many of the body's sensory systems.