Identification of histaminic (H1-type) receptors in small intestine of broilers by application of histamine and some of its agonists and antagonists.
Histamine is a biologically active amine (biogenic amine) that has a broad spectra of physiologic and pathologic reactions in the organism. Its effects are shown through 4 types of specific receptors (H1, H2, H3 and H4). Histamine is one of the main causes of intestine disorders and the occurrence of diarrhea, both of which are very common in broilers. Whilst there is no information in scientific literature about the presence of histaminic receptors in smooth muscles of the small intestine wall of broilers (duodenum, jejunum and ileum), we tried to determine their presence, distribution and type in this kind of muscles. Investigations were carried out on isolated smooth muscles of the circular and longitudinal layer of the broiler small intestine (strip dimension 3-4 mm x 2 cm). The muscle strip was then placed in an isolated organ bath and the contractions obtained were registered with isometric transducers on a two-channel printer. This was done following the addition of histamine, betahistine (H1 agonist), and mepiramine (H1 antagonist). Muscle vitality was checked by adding acethylcholine chloride. Using the obtained results, it can be concluded that H1 types of histaminergic receptors are present in smooth muscles of the small intestine of broilers. .