5-HT4 is a human serotonin G protein-coupled receptor. Several studies suggested that intact 5-HT systems are important determinants of sensitivity and/or tolerance to ethanol-induce ataxia hypothermia. Attenuated response to stress and novelty and hypersensitivity to seizures in 5-HT receptor knock-out mice. Neuropsychiatric disorders such as anxiety, depression, migraine, vasospasm and epilepsy may involve different subtypes of the 5-HT receptor.