5-HT1B receptor
5-hydroxytryptamine receptor 1B also known as the 5-HT receptor is a protein that in humans is encoded by the "HTR1B" gene. The 5-HT receptor is a 5-HT receptor subtype. Tissue distribution and function. 5-HT receptors are widely distributed throughout the central nervous system with the highest concentrations found in the frontal cortex, basal ganglia, striatum, and the hippocampus. The function of the 5-HT receptor differs depending upon its location. In the frontal cortex, it is believed to act as a postsynaptic receptor inhibiting the release of dopamine. In the basal ganglia  and the striatum, evidence suggests 5-HT signaling acts on an autoreceptor, inhibiting the release of serotonin and decreasing glutamatergic transmission by reducing miniature excitatory postsynaptic potential (mEPSP) frequency, respectively. In the hippocampus, a recent study has demonstrated that activation of postsynaptic 5-HT heteroreceptors produces a facilitation in excitatory synaptic transmission which is altered in depression. When the expression of 5-HT in human cortex was traced throughout life, significant changes during adolescence were observed, in a way that is strongly correlated with the expression of 5-HT. Outside the brain, 5-HT receptor activation also has vascular effects , such as pulmonary vasoconstriction, which may be beneficial to the treatment of miagraine. When the 5HT1B agonist sumatriptan was first developed, one of the study participants experienced a cardiovascular event in response to intravenous administration of the drug, so this agonist is contraindicated for patients with cardiovascular disease. Blocking 5-HT receptor signalling also increases the number of osteoblasts, bone mass, and the bone formation rate. Knockout mice lacking the 5-HT gene have been reported to have a higher preference for alcohol, although later studies failed to replicate such abnormalities in alcohol consumption. These mice have also been reported  to have a lower measure of anxiety (such as on the elevated plus maze test) and a higher measure of aggression. Under basal conditions, knockout mice present with a "normal" phenotype and exhibit a sucrose preference (lack of sucrose preference is considered a measure of anhedonia). However, after undergoing chronic unpredictable stress treatment to induce a "depression-like" phenotype these animals do not benefit from administration of selective serotonin reuptake inhibitor (SSRIs). Genetics. In humans the protein is coded by the gene "HTR1B". A genetic variant in the promoter region, "A-161T", has been examined with respect to personality traits  and showed no major effect.