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Epithelial Function and Airway Responsiveness
Published in Alastair G. Stewart, AIRWAY WALL REMODELLING in ASTHMA, 2020
Roy G. Goldie, Janet M. H. Preuss
Furthermore, recent evidence suggests that histaminase present in guinea pig tracheal epithelium contributes to the inhibitory effect of the epithelium on histamine-induced contraction.178 Metabolism of histamine can also occur in human bronchial epithelium via histamine N-methyltransferase, inhibition of which caused enhanced contractile responses to histamine.179 In isolated guinea pig tracheal strips, the epithelium may be a major site of extraneuronal uptake and O-methylation of catecholamines, such as isoprenaline.180 The guinea pig tracheal epithelium may also be a site for the uptake and degradation of adenosine.180,181
Xenobiotic Biotransformation
Published in Robert G. Meeks, Steadman D. Harrison, Richard J. Bull, Hepatotoxicology, 2020
Histamine N-methyltransferase is ubiquitous in nature; its activity is principally cytosolic. The enzyme has strict specificity for histamine as a methyl acceptor. It is sensitive to inhibition by high substrate concentrations of histamine.
Biogenic Amines in Plant Food
Published in Akula Ramakrishna, Victoria V. Roshchina, Neurotransmitters in Plants, 2018
Kamil Ekici, Abdullah Khalid Omer
Numerous enzymatic techniques, including catalyst connected immunosorbent examine Enzyme Linked Immuno-Sorbent Assay (ELISA), have been created to recognize histamine in blood and tissues. Enzymatic strategies use histamine N-methyltransferase and radioactive S-adenosylmethionine. In any case, these strategies and the ELISA procedure have not been connected to sustenances.
Investigation on beneficial role of l -carnosine in neuroprotective mechanism of ischemic postconditioning in mice: possible role of histidine histamine pathway
Published in International Journal of Neuroscience, 2020
Jasleen Kaur Virdi, Amritansh Bhanot, Amteshwar Singh Jaggi, Neha Agarwal
Histamine holds an important place as a neurotransmitter in the central nervous system. The tuberomamillary nucleus in the hypothalamus consists of some of the histaminergic neurons, with their fibers distributed widely throughout the brain [11]. The general states of metabolism, consciousness and memory are under the command of the histaminergic system [12]. Histamine does not have the ability to permeate through the blood brain barrier; therefore, it is not transported in the brain from plasma. It is directly synthesized in the brain tissue from L-histidine by a specific enzyme, L-histidine decarboxylase (HDC) [13]. There are four histamine receptors which have been identified (H1-H4), with H4 being discovered recently [14]. Out of these four histamine receptors, H1-H3 are ubiquitously expressed in the brain, while H4 receptors are predominantly found in the periphery i.e. in bone marrow and leukocytes [15]. The H3 receptors are mainly located in the pre-synapse, unlike H1 and H2 receptors and the H3 receptors signal through Gi/Go proteins and display substantial constitutive activity which imposes negative control on the synthesis of histamine [16]. Moreover, a number of studies indicate that histamine and its receptors hold significant importance in cerebral ischemia by producing their actions on multiple targets [17]. Histidine-histamine pathway is involved in the formation of histamine from histidine. It involves decarboxylation of the amino acid L-histidine in a reaction catalyzed by the enzyme HDC. The major routes of histamine inactivation in mammals are methylation of the imidazole ring catalyzed by histamine N-methyltransferase and oxidative deamination of the primary amino group catalyzed by diamine oxidase [18]. Involvement of histamine has been proved to be protective in cerebral ischemia by altering the level of neurotransmitters in the brain, CBF, edema, inflammation and cerebral reconstruction [19].
Acute coronary syndrome from scombroid poisoning: a narrative review of case reports
Published in Clinical Toxicology, 2022
Cesare de Gregorio, Giuseppe Ferrazzo, Ioanna Koniari, Nicholas G. Kounis
Two enzymes inactivate ingested histamine [14]. First, diamine oxidase (DAO) in the intestinal epithelium acts on ingested histamine prior to entering the portal circulation. In the liver, histamine-N-methyltransferase (HNMT) also inactivates histamine by ring methylation. Intoxication occurs after saturating these counteractive mechanisms [8–14].