H₃ receptor

Jump to: navigation, search
histamine receptor H3
Identifiers
SymbolHRH3
Entrez11255
HUGO5184
OMIM604525
RefSeqNM_007232
UniProtQ9Y5N1
Other data
LocusChr. 20 pter-p12.1

H3 receptors are expressed in the central nervous system and, to a lesser extent, the peripheral nervous system, where they act as autoreceptors in presynaptic histaminergic neurons, and control histamine turnover[1] by "feedback inhibition of histamine synthesis and release as well."[2] The H3also been shown to presynaptically inhibit the release of a number of other neurotransmitters (i.e. it acts as an inhibitory heteroreceptor) including, but probably not limited to dopamine, GABA, acetylcholine, noradrenaline, and serotonin.

It has been proposed as a target for treating sleep disorders.[3]

Locations of H3 receptors

Pharmacology

Like all histamine receptors the H3 receptor is a G-protein coupled receptor. The H3 receptor is coupled to the Gi G-protein, so it leads to inhibition of the formation of cAMP. Also, the β and γ subunits interact with N-type voltage gated calcium channels, to reduce action potential mediated influx of calcium and hence reduce neurotransmitter release.

The gene sequence for H3 receptors expresses only about 30% homology with both H1 and H2 receptors. The diverse expression of H3 receptors throughout the cortex and subcortex indicates its ability to modulate the release of a large number of neurotransmitters. Because of this, H3 receptor ligands are being investigated for the treatment of numerous neurological conditions, including obesity (because of the histamine/orexinergic system interaction), movement disorders (because of H3 receptor-modulation of dopamine and GABA in the basal ganglia), schizophrenia and ADHD (again because of dopamine modulation) and research is even underway as to whether H3 receptor ligands could be useful in modulating wakefulness (because of effects on noradrenaline, glutamate and histamine)

Isoforms

There are at least six H3 receptor isoforms in the human, and up to 12 discovered so far.[4] In rats there has been six H3 receptor subtypes reported so far. Mice also have three reported isoforms.[5] These subtypes all have subtle difference in their pharmacology (and presumably distribution, based on studies in rats) but the exact physiological role of these isoforms is still unclear.

History

H3 receptors agonists and antagonists

H3-receptor Agonists

Currently no therapeutic products selective for H3 receptors. Some, though not totally selective, are:

H3-receptor Antagonists

These include:[12]

see antihistamines - H3-receptor antagonists

References

  1. Abbott's H3 histamine receptor antagonist, ABT-239, a candidate treatment of cognitive disorders, ADHD, Alzheimer's and schizophrenia
  2. RE West, A Zweig, NY Shih, MI Siegel, RW Egan and MA Clark (1990). "Identification of two H3-histamine receptor subtypes". Molecular Pharmacology. 38 (5): 610–613. PMID 2172771. Reprint (PDF, subscription required)
  3. Passani MB, Lin JS, Hancock A, Crochet S, Blandina P (2004). "The histamine H3 receptor as a novel therapeutic target for cognitive and sleep disorders". Trends Pharmacol. Sci. 25 (12): 618–25. doi:10.1016/j.tips.2004.10.003. PMID 15530639.
  4. Bakker RA (2004). "Histamine H3-receptor isoforms". Inflammation Research. 53 (10): 509–16. PMID 15597144. Fulltext options
  5. Rouleau A, Heron A, Cochois V, Pillot C, Schwartz JC, Arrang JM. Cloning and expression of the mouse histamine H3 receptor: evidence for multiple isoforms. J Neurochem. 2004 Sep;90(6):1331-8.
  6. Arrang JM, Garbarg M, Schwartz JC. Auto-inhibition of brain histamine release mediated by a novel class (H3) of histamine receptor. Nature. 1983 Apr 28;302(5911):832-7.
  7. Schlicker E, Betz R, Gothert M. Histamine H3 receptor-mediated inhibition of serotonin release in the rat brain cortex. Naunyn Schmiedebergs Arch Pharmacol. 1988 May;337(5):588-90.
  8. Eiichiro Hatta, Keishu Yasuda and Roberto Levi. Activation of Histamine H3 Receptors Inhibits Carrier-Mediated Norepinephrine Release in a Human Model of Protracted Myocardial Ischemia Pharmacology and Experimental Therapeutics Vol. 283, Issue 2, 494-500, 1997
  9. T.W. Lovenberg et al., Cloning and functional expression of the human histamine H3 receptor. Mol. Pharmacol. 55 (1999), pp. 1101–1107
  10. Roberto Levi and Neil C. E. Smith (2000). "Histamine H3-Receptors: A New Frontier in Myocardial Ischemia". Journal of Pharmacology and Experimental Therapeutics. 292 (3): 825–830. PMID 10688593. Fulltext options
  11. Toyota H, Dugovic C, Koehl M, Laposky A, Weber C, Ngo K, Wu Y, Lee D, Yanai K, Sakurai E, Watanabe T, Liu C, Chen J, Barbier A, Turek F, Fung-Leung W, Lovenberg T (2002). "Behavioral characterization of mice lacking histamine H(3) receptors". Mol Pharmacol. 62 (2): 389–97. PMID 12130692. link
  12. Development of trans-2-(1H-Imidazol-4-yl) Cyclopropane Derivatives as New High-Affinity Histamine H3 Receptor Ligands.

External links


Linked-in.jpg