Histamine H 3 receptor
| Histamine H 3 receptor | ||
|---|---|---|
| Properties of human protein | ||
| Mass / length primary structure | 445 AS ; 48.7 kDa | |
| Secondary to quaternary structure | 7TM | |
| Identifier | ||
| Gene name | HRH3 | |
| External IDs | ||
| Occurrence | ||
| Parent taxon | Vertebrates | |
The histamine H 3 receptor (abbreviated H 3 receptor ) is a protein from the family of histamine receptors that by the body's tissue hormone histamine can be activated. In the human body, the H 3 receptor is found in particular presynaptically on nerve cells of the central nervous system and the peripheral nervous system . As autoreceptors , they are involved in reducing the further release of histamine through negative feedback and, as heteroreceptors, regulate the release of the neurotransmitters acetylcholine , noradrenaline and serotonin . Through these mechanisms, H 3 receptors are involved in the central regulation of feelings of hunger and thirst , body temperature and blood pressure.
biochemistry
genetics
The human H 3 receptor was first cloned in 1999 . It is encoded by a gene on chromosome 20 on the gene locus 20q13.33. The coding DNA sequence contains three exons and two introns .
Protein structure
The human H 3 receptor protein consists of 445 amino acids . Alternative splice variants of different lengths are also described and differ in particular in the size of the third intracellular loop. As for many other receptors from the family of G protein-coupled receptors , a structure with seven helical transmembrane domains is assumed for the H 3 receptor ( heptahelical receptor ).
Signal transduction
At the molecular level, stimulation of H 3 receptors leads to activation of G i / o proteins and inhibition of adenylyl cyclase . In addition, H 3 receptors regulate the activity of calcium channels and thus the release of neurotransmitters from vesicles.
function
As an auto and heteroreceptor for neurotransmitters, the H 3 receptor is associated with the central regulation of hunger and thirst, the day-night rhythm, body temperature and blood pressure. In addition, this receptor is said to play a role, directly or indirectly, in the pathophysiology of neurological pain, schizophrenia , Parkinson's disease and ADHD .
pharmacology
Agonists and antagonists of histamine at the H 3 receptor are currently being investigated for their therapeutic potential in the treatment of sleep disorders, obesity, neurological pain, schizophrenia and ADHD . (R) -α-methylhistamine, Immepip and Imetit could be identified as selective H 3 receptor agonists . Important antagonists are A-349,821, ABT-239, Burimamid , Ciproxifan , Conessin, Clobenpropit, Impentamine and Thioperamide . Cipralisant and Proxifan show a functional selectivity and behave as agonists or antagonists depending on the examined signal.
Individual evidence
- ↑ Lovenberg TW, Roland BL, Wilson SJ, et al : Cloning and functional expression of the human histamine H3 receptor . In: Mol. Pharmacol. . 55, No. 6, June 1999, pp. 1101-7. PMID 10347254 .
- ↑ Bakker RA: Histamine H3-receptor isoforms . In: Inflamm. Res. . 53, No. 10, October 2004, pp. 509-16. doi : 10.1007 / s00011-004-1286-9 . PMID 15597144 .