Histamine H3 receptor (H3R) (H3R)

The Histamine H3 receptor (H3R) is a G protein-coupled receptor primarily located on presynaptic terminals in the central nervous system of rats [1, 3]. It functions as an autoreceptor, inhibiting the synthesis and release of histamine, and as a heteroreceptor, modulating the release of other neurotransmitters such as acetylcholine, glutamate, and GABA [1, 4]. In the rat brain, H3R is highly expressed in regions involved in arousal and cognition, including the thalamus, striatum, and cerebral cortex [1, 5]. The receptor exhibits high constitutive activity, which allows inverse agonists to effectively increase neurotransmitter levels and promote wakefulness [4]. Consequently, the H3R is a significant therapeutic target for conditions characterized by excessive daytime sleepiness, such as narcolepsy, and cognitive deficits associated with Alzheimer's disease or ADHD [3, 5]. Drugs like pitolisant, which act as inverse agonists, have demonstrated efficacy in preclinical rat models and clinical settings by enhancing histaminergic signaling [2, 4]. Research in rats has also suggested a role for H3R in energy homeostasis, making it a potential target for obesity treatment [5]. Furthermore, the diversity of H3R isoforms in rats, resulting from alternative splicing, adds a layer of complexity to its pharmacological profile and functional regulation [1, 3].

Other names

HRH3Histamine receptor H3H3 histamine receptorRat histamine H3 receptor

Inverse agonism and antagonism of the presynaptic H3 receptor to increase the release of histamine and other neurotransmitters [2, 4].