Serotonin (5-hydroxytryptamine, 5-HT) plays unequivocally a most important role in the normal physiology amongst higher eukaryotes, as do most neurotransmitters. The physiological roles of serotonin and its receptors range from appetite, regulation of the circadian rhythm, sexual behavior, memory and nociception. Serotonin is also involved in migraine and some psychiatric diseases such as depression anxiety and aggression¹. Serotonin and its receptors also have an influence on the cardiovascular, pulmonary, gastrointestinal (GI) and genitourinary systems².

To date, some fifteen serotonin receptors have been cloned and grouped into seven families (5-HT1-5-HT7) based on their signaling mechanisms. The 5-HT1 receptor class comprises 5 different receptors with ranging homology. Apart from 5-HT3, all serotonin receptors belong to the G-protein coupled receptor superfamily and therefore span the membrane seven times³.

The 5-hydroxytryptamine receptor 1B (5-HT1B) is involved in several physiological behaviors and psychiatric diseases, including locomotor activity, drug abuse reinforcement, migraine, anxiety states and aggressive behaviors¹.

Pharmacological studies suggest that 5-HT1B is expressed by both serotonergic and non-serotonergic neurons. In the nervous system, this receptor is located in the axon terminal of the plasma membrane of unmyelinated axons. It is predominantly localized on pre-synaptic membranes. Signal transduction studies of the receptor indicate that this receptor is coupled negatively to adenylyl cyclase as its activation induces a decrease in adenylyl cyclase activity¹.