Thursday, 12 December 2013

The Effects of Hormone Histamine (1)

Histamine, found within granules of basophils and mast cells (>90% of body stores) is a biogenic amine and an organic nitrogen compound that occurs to various degrees in many foods such as cherries to about 0.17-13.46 ng/g, bananas and grapes, rice and cereals, herbs, olive oil, wine, beer, etc.. In healthy persons, dietary histamine can be rapidly detoxified by amine oxidases, whereas persons with low amine oxidase activity are at risk of histamine toxicity(a). the hormone, as a neurotransmitter is involved in regulating physiological function in the gut and immune response to foreign pathogens.

1. Histamine regulation in glucose and lipid metabolism via histamine receptors
In the study to to evaluate histamine regulation of glucose and lipid metabolism and development of nonalcoholic steatohepatitis (NASH) with a hyperlipidemic diet, showed that severe NASH with hypoadiponectinemia as well as hepatic triglyceride and free cholesterol accumulation and increased blood hepatic enzymes were observed in H2R(-/-) mice. H1R(-/-) mice showed an obese phenotype with visceral adiposity, hyperleptinemia, and less severe hepatic steatosis and inflammation with increased hepatic triglyceride. These data suggest that H1R and H2R signaling may regulate glucose(1).

2. Histamine intolerance
According to the study of University of Bonn, Bonn, diamine oxidase (DAO) is the main enzyme for the metabolism of ingested histamine. It has been proposed that DAO, when functioning as a secretory protein, may be responsible for scavenging extracellular histamine after mediator release. Conversely, histamine N-methyltransferase, the other important enzyme inactivating histamine, is a cytosolic protein that can convert histamine only in the intracellular space of cells. An impaired histamine degradation based on reduced DAO activity and the resulting histamine excess may cause numerous symptoms mimicking an allergic reaction. The ingestion of histamine-rich food or of alcohol or drugs that release histamine or block DAO may provoke diarrhea, headache, rhinoconjunctival symptoms, asthma, hypotension, arrhythmia, urticaria, pruritus, flushing, and other conditions in patients with histamine intolerance. Symptoms can be reduced by a histamine-free diet or be eliminated by antihistamines(2). 

3. The role of histamine H1 and H4 receptors in allergic inflammation
Antihistamines are inflammatory responses resulting from the liberation of histamine have long been thought to be mediated by the histamine H1 receptor, and H1-receptor antagonists, researchers at the Johnson & Johnson Pharmaceutical Research & Development, L.L.C. San Diego, suggested that histamine indeed has roles in inflammation and immune function modulation in such diseases. In particular, the discovery of a fourth histamine receptor (H4) and its expression on numerous immune and inflammatory cells has prompted a re-evaluation of the actions of histamine, suggesting a new potential for H4-receptor antagonists and a possible synergy between H1 and H4-receptor antagonists in targeting various inflammatory conditions(3).

4. Oral provocation with liquid histamine
75 mg of pure liquid oral histamine--a dose found in normal meals--can provoke immediate as well as delayed symptoms in 50% of healthy females without a history of food intolerance. In a randomized, double-blind, placebo-controlled cross-over study in 10 healthy females (age range 22-36 years, mean 29.1 +/- 5.4) who were hospitalized and challenged on two consecutive days with placebo (peppermint tea) or 75 mg of pure histamine (equaling 124 mg histamine dihydrochloride, dissolved in peppermint tea), researchers found that after histamine challenge, 5 of 10 subjects showed no reaction. One individual experienced tachycardia, mild hypotension after 20 minutes, sneezing, itching of the nose, and rhinorrhea after 60 minutes. Four subjects experienced delayed symptoms like diarrhea (4x), flatulence (3x), headache (3x), pruritus (2x) and ocular symptoms (1x) starting 3 to 24 hours after provocation. No subject reacted to placebo. No changes were observed in histamine and DAO levels within the first 80 minutes in non-reactors as well as reactors. There was no difference in challenge with histamine versus challenge with placebo(4).

5. Atopic Dermatitis with a Low-histamine Diet
In a study to evaluate a six-year-old Korean boy with AD admitted to the hospital for evaluation of the possibility of food, particularly pork, as a triggering factor in his skin disease, found that in an oral food challenge test, he showed a positive result after eating 200 g of pork, but did not show a positive result after eating 60 g of pork. After discharge, we attempted to keep him on a balanced diet that included various types of food and prohibited him from eating food that contains a high level of histamine. After keeping the patient on a balanced and low-histamine dietary regimen, his AD symptoms showed improvement and have not worsened for more than seven months. A low-histamine, balanced diet could be helpful for AD patients having symptoms that resemble histamine intolerance in which their AD symptoms worsened after intake of histamine-rich foods, but in which food allergy tests are negative(5).

6. Histamine H3 receptors and sleep-wake regulation
The histamine H(3) receptors are autoreceptors damping histamine synthesis, the firing frequency of histamine neurons, and the release of histamine from axonal varicosities. It is noteworthy that this action also extends to heteroreceptors on the axons of most other neurotransmitter systems, allowing a powerful control over multiple homeostatic functions. The particular properties and locations of histamine H(3) receptors provide quite favorable attributes to make this a most promising target for pharmacological interventions of sleep and waking disorders associated with narcolepsy, Parkinson's disease, and other neuropsychiatric indications, according to the study of Integrative Physiology of Brain Arousal Systems, Claude Bernard University(6).

7.  Histamine and neuropsychiatric disorders
Brain histamine is involved in a wide range of physiological functions such as regulation of sleep-wake cycle, arousal, appetite control, cognition, learning and memory mainly through the 4 receptor subtypes: H1, H2, H3 and H4, according to the study of Dr. Tashiro M, and Dr. Yanai K. at the Tohoku University Cyclotron and Radioisotope Centre, a series of clinical studies on histamine H1 antagonists, or antihistamines, have demonstrated that antihistamines can be classified into sedative, mildly-sedative and non-sedative drugs according to their blood-brain barrier (BBB) permeability, showing apparent clinical usefulness regarding QOL, work efficiency and traffic safety of allergic patients. PET has also been used for elucidation of aging effects and pathophysiological roles of histaminergic nervous system in various neuropsychiatric disorders such as Alzheimer's disease, schizophrenia and depression, where H1 receptor binding potentials were lower than age-matched healthy controls. It has been also demonstrated that brain histamine functions as an endogenous anti-epileptic. In addition, H3 receptors are located in the presynaptic sites of not only histaminergic nerves but also in other nervous systems such as serotonergic, cholinergic and dopaminergic systems, and to be regulating secretion of various neurotransmitters. Nowadays, H3 receptors have been thought to be a new target of drug treatment of various neuropsychiatric disorders(7). 

8. Histamine and men sexual arousal
In the study to evaluate the course of histamine plasma levels through different stages of sexual arousal in the systemic and cavernous blood of healthy male subjects of 34 healthy men, researchers at the Department of Urology & Urological Oncology, Hannover Medical School, showed that histamine slightly decreased in the cavernous blood when the penis became tumescent. During rigidity, histamine decreased further but remained unaltered in the phase of detumescence and after ejaculation. In the systemic circulation, no alterations were observed with the initiation or termination of penile erection, whereas a significant drop was registered following ejaculation. Results are not in favour of the hypothesis of an excitatory role of histamine in the control of penile erection. Nevertheless, the amine might mediate biological events during the post-ejaculatory period(8). 

9.The role of histamine on cognition
The specific participation of histamine in cognitive functions followed a slow and unclear pathway because the many different experimental learning models, pharmacologic approaches, systemic and localized applications of the histamine active compounds into the brain used by researchers showed facilitating or inhibitory effects on learning, generating an active issue that has extended up to present time. The specific histamine receptors and the compartmentalizing proprieties of the brain that might explain the apparent inconsistent effects of the imidazolamine in learning. In addition, a hypothetical physiologic role for histamine in memory is proposed under the standard theories of learning in experimental animals and humans.according to the study of Dr. Edgardo O. Alvarez at the Universidad Nacional de Cuyo, Laboratorio de Neuropsicofarmacología Experimenta(9).
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