May play a role in vasoconstriction summary for HTR1D Gene: Serotonin 5-HT1D receptors, previously known as 5-HT1Dalpha receptors, are located primarily in the basalganglia, hippocampus, cortex, spinal cord and vascular smooth muscle cells. 5-HT1D receptors are thought tobe involved in anxiety, depression, and other neuropsychiatric disorders.