5-HT1A receptor

The 5-HT_1A receptor is a subtype of 5-HT receptor that binds the endogenous neurotransmitter serotonin (5-hydroxytryptamine, 5-HT). It is a G protein-coupled receptor (GPCR) that is coupled to G_i/G_o and mediates inhibitory neurotransmission. HTR1A denotes the human gene encoding for the receptor.

Distribution

The 5-HT_1A receptor is the most widespread of all the 5-HT receptors. In the central nervous system, 5-HT_1A receptors exist in the cerebral cortex, hippocampus, septum, amygdala, and raphe nucleus in high densities, while low amounts also exist in the basal ganglia and thalamus. The 5-HT_1A receptors in the raphe nucleus are largely somatodendritic autoreceptors, whereas those in other areas such as the hippocampus are postsynaptic receptors.

Function

Neuromodulation

5-HT_1Areceptor agonists are involved in neuromodulation. They decrease blood pressure and heart rate via a central mechanism, by inducing peripheral vasodilation, and by stimulating the vagus nerve. These effects are the result of activation of 5-HT_1A receptors within the rostral ventrolateral medulla. The sympatholytic antihypertensive drug urapidil is an α₁-adrenergic receptor antagonist and α₂-adrenergic receptor agonist, as well as 5-HT_1A receptor agonist, and it has been demonstrated that the latter property contributes to its overall therapeutic effects. Vasodilation of the blood vessels in the skin via central 5-HT_1A activation increases heat dissipation from the organism out into the environment, causing a decrease in body temperature.