Nucleus raphe pallidus
It has been implied that the preoptic area is constantly inhibiting the raphe pallidus, especially the rostral portion, with GABA.When the preoptic area receives immune signals from the body, the inhibition stops and the rostral portion of the nucleus raphe pallidus excites the intermediolateral cell column, which induces a fever.[2] The nucleus raphe pallidus has also been known to mediate the tachycardia response, an extremely high heart rate known to be incited by emotional or psychological stress.Microinjections of a GABA-a antagonist into the nucleus raphe pallidus, induces an increased heart rate.Conversely, microinjections of muscimol, a GABA-a agonist, inhibit tachycardia in rats under air-stress stimuli.