Humans ; Histamine ; Receptors, Histamine H2 ; Schizophrenia/drug therapy*

Basal Forebrain ; Cholinergic Agents ; Cholinergic Neurons ; Humans ; Receptors, Histamine H1 ; Schizophrenia

Spinal α-motoneurons directly innervate skeletal muscles and function as the final common path for movement and behavior. The processes that determine the excitability of motoneurons are critical for the execution of motor behavior. In fact, it has been noted that spinal motoneurons receive various neuromodulatory inputs, especially monoaminergic one. However, the roles of histamine and hypothalamic histaminergic innervation on spinal motoneurons and the underlying ionic mechanisms are still largely unknown. In the present study, by using the method of intracellular recording on rat spinal slices, we found that activation of either H or H receptor potentiated repetitive firing behavior and increased the excitability of spinal α-motoneurons. Both of blockage of K channels and activation of Na-Ca exchangers were involved in the H receptor-mediated excitation on spinal motoneurons, whereas the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels were responsible for the H receptor-mediated excitation. The results suggest that, through switching functional status of ion channels and exchangers coupled to histamine receptors, histamine effectively biases the excitability of the spinal α-motoneurons. In this way, the hypothalamospinal histaminergic innervation may directly modulate final motor outputs and actively regulate spinal motor reflexes and motor execution.
Animals ; Histamine ; pharmacology ; Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels ; metabolism ; Motor Neurons ; drug effects ; physiology ; Rats ; Receptors, Histamine H2 ; metabolism ; Sodium-Calcium Exchanger ; metabolism

Antipsychotic-induced weight gain (AIWG) is a common adverse effect of this treatment, particularly with second-generation antipsychotics, and it is a major health problem around the world. We aimed to review the progress of pharmacogenetic studies on AIWG in the Chinese population to compare the results for Chinese with other ethnic populations, identify the limitations and problems of current studies, and provide future research directions in China. Both English and Chinese electronic databases were searched to identify eligible studies. We determined that > 25 single-nucleotide polymorphisms in 19 genes have been investigated in association with AIWG in Chinese patients over the past few decades. HTR2C rs3813929 is the most frequently studied single-nucleotide polymorphism, and it seems to be the most strongly associated with AIWG in the Chinese population. However, many genes that have been reported to be associated with AIWG in other ethnic populations have not been included in Chinese studies. To explain the pharmacogenetic reasons for AIWG in the Chinese population, genome-wide association studies and multiple-center, standard, unified, and large samples are needed.
Antipsychotic Agents ; adverse effects ; Asian Continental Ancestry Group ; genetics ; China ; Genome-Wide Association Study ; Genotype ; Humans ; Lipid Metabolism ; genetics ; Neurosecretory Systems ; drug effects ; Pharmacogenomic Testing ; Polymorphism, Single Nucleotide ; Receptors, Adrenergic ; genetics ; Receptors, Dopamine ; genetics ; Receptors, Histamine ; genetics ; Receptors, Serotonin ; genetics ; Weight Gain ; drug effects ; genetics

BACKGROUND/AIMS: Food intolerance/malabsorption, particularly histamine intolerance (HIT), may cause nonspecific functional gastrointestinal and extraintestinal symptoms. We evaluated gastrointestinal and extraintestinal symptoms in patients with HIT. METHODS: In an analysis of outpatients' charts we identified 133 patients, who presented with recurring nonspecific functional gastrointestinal, extraintestinal symptoms, and a diamine oxidase value <10 U/mL, indicative of HIT. A standardized anonymous questionnaire with symptoms of HIT based on known symptoms and the 4 histamine receptors including gastrointestinal, cardiovascular, respiratory and skin complaints was developed, and sent by mail to the patients. RESULTS: In the 62 patients that completed the questionnaire, bloating was the most common and most serious symptom. Other commonly reported gastrointestinal symptoms were postprandial fullness, diarrhea, abdominal pain, and constipation. The presence of 2 from a list of 24 symptoms resulted in 276 various symptom combinations. From calculated 2.024 possible combinations of 3 symptoms the patients with HIT presented 1.975 combinations. CONCLUSIONS: The knowledge of this wide variability of symptoms and complex symptom combinations in patients with HIT may help to clinically recognize and diagnose HIT.
Abdominal Pain ; Amine Oxidase (Copper-Containing) ; Anonyms and Pseudonyms ; Constipation ; Diarrhea ; Gastrointestinal Diseases ; Glutens ; Histamine ; Humans ; Irritable Bowel Syndrome ; Postal Service ; Receptors, Histamine ; Skin

Chronic spontaneous urticaria (CSU), also known as chronic idiopathic urticaria, is a common chronic inflammatory skin disorder that has a prevalence of 0.5% to 1% in the general population. It affects daily normal life and work productivity, with significant impacts on quality of life. Generally, the management of CSU uses a step-wise approach. Although second-generation H1 antihistamines are an effective mainstay of CSU, approximately 20% of patients are resistant to conventional antihistamine monotherapy. Evidence-based and expert consensus-based treatment guidelines of CSU can be a useful resource for primary care physicians and specialists. This review presents diverse information to support decision-making for individualized treatment plans in this special population. Several major therapeutic advances have occurred in recent years. Omalizumab, an immunoglobulin G humanized monoclonal anti-immunoglobulin E antibody that prevents binding of immunoglobulin E to the high-affinity immunoglobulin E receptor has shown safety and efficacy in patients with intractable CSU. In well-controlled clinical trials in patients with refractory CSU who received add-on therapy with subcutaneous omalizumab (300 mg every 4 weeks for 12 or 24 weeks), the rates of complete response were significantly higher in the omalizumab group (relative risk, 4.55; P < 0.0001). The introduction of omalizumab as an add-on therapy to H1 antihistamines as a management option has markedly improved the therapeutic possibilities for CSU and the quality of life of CSU patients. Nevertheless, many patients still do not tolerate or benefit from existing therapies, including omalizumab. There are ongoing studies investigating the treatment potential of novel therapeutic targets in CSU.
Efficiency ; Histamine Antagonists ; Humans ; Immunoglobulin E ; Immunoglobulin G ; Immunoglobulins ; Omalizumab ; Physicians, Primary Care ; Prevalence ; Quality of Life ; Receptors, IgE ; Skin ; Specialization ; Urticaria

Going back to basics prior to mentioning the use of antipsychotics in patients with pain, the International Association for the Study of Pain (IASP) definition of pain can be summarized as an unpleasant experience, composed of sensory experience caused by actual tissue damage and/or emotional experience caused by potential tissue damage. Less used than antidepressants, antipsychotics have also been used for treating this unpleasant experience as adjuvant analgesics without sufficient evidence from research. Because recently developed atypical antipsychotics reduce the adverse reactions of extrapyramidal symptoms, such as acute dystonia, pseudo-parkinsonism, akathisia, and tardive dyskinesia caused by typical antipsychotics, they are expected to be used more frequently in various painful conditions, while increasing the risk of metabolic syndromes (weight gain, diabetes, and dyslipidemia). Various antipsychotics have different neurotransmitter receptor affinities for dopamine (D), 5-hydroxytryptamine (5-HT), adrenergic (α), histamine (H), and muscarinic (M) receptors. Atypical antipsychotics antagonize transient, weak D₂ receptor bindings with strong binding to the 5-HT(2A) receptor, while typical antipsychotics block long-lasting, tight D₂ receptor binding. On the contrary, antidepressants in the field of pain management also block the reuptake of similar receptors, mainly on the 5-HT and, next, on the norepinephrine, but rarely on the D receptors. Antipsychotics have been used for treating positive symptoms, such as delusion, hallucination, disorganized thought and behavior, perception disturbance, and inappropriate emotion, rather than the negative, cognitive, and affective symptoms of psychosis. Therefore, an antipsychotic may be prescribed in pain patients with positive symptoms of psychosis during or after controlling all sensory components.
Affective Symptoms ; Analgesics ; Antidepressive Agents ; Antipsychotic Agents ; Delusions ; Dopamine ; Drug-Related Side Effects and Adverse Reactions ; Dystonia ; Hallucinations ; Histamine ; Humans ; Movement Disorders ; Norepinephrine ; Pain Management ; Prolactin ; Psychomotor Agitation ; Psychotic Disorders ; Receptor, Serotonin, 5-HT2A ; Receptors, Neurotransmitter ; Serotonin ; Weight Gain

The ventral pallidum (VP) is a crucial component of the limbic loop of the basal ganglia and participates in the regulation of reward, motivation, and emotion. Although the VP receives afferent inputs from the central histaminergic system, little is known about the effect of histamine on the VP and the underlying receptor mechanism. Here, we showed that histamine, a hypothalamic-derived neuromodulator, directly depolarized and excited the GABAergic VP neurons which comprise a major cell type in the VP and are responsible for encoding cues of incentive salience and reward hedonics. Both postsynaptic histamine H1 and H2 receptors were found to be expressed in the GABAergic VP neurons and co-mediate the excitatory effect of histamine. These results suggested that the central histaminergic system may actively participate in VP-mediated motivational and emotional behaviors via direct modulation of the GABAergic VP neurons. Our findings also have implications for the role of histamine and the central histaminergic system in psychiatric disorders.
Action Potentials ; drug effects ; Animals ; Basal Forebrain ; cytology ; Dimaprit ; pharmacology ; Dose-Response Relationship, Drug ; Electric Stimulation ; Female ; GABAergic Neurons ; drug effects ; Histamine ; pharmacology ; Histamine Agonists ; pharmacology ; Lysine ; analogs & derivatives ; metabolism ; Male ; Patch-Clamp Techniques ; Pyridines ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Histamine H1 ; metabolism ; Receptors, Histamine H2 ; metabolism ; Sodium Channel Blockers ; pharmacology ; Tetrodotoxin ; pharmacology ; gamma-Aminobutyric Acid ; metabolism

Cyproheptadine (CPH), a first-generation antihistamine, enhances the delayed rectifier outward K current (I) in mouse cortical neurons through a sigma-1 receptor-mediated protein kinase A pathway. In this study, we aimed to determine the effects of CPH on neuronal excitability in current-clamped pyramidal neurons in mouse medial prefrontal cortex slices. CPH (10 µmol/L) significantly reduced the current density required to generate action potentials (APs) and increased the instantaneous frequency evoked by a depolarizing current. CPH also depolarized the resting membrane potential (RMP), decreased the delay time to elicit an AP, and reduced the spike threshold potential. This effect of CPH was mimicked by a sigma-1 receptor agonist and eliminated by an antagonist. Application of tetraethylammonium (TEA) to block I channels hyperpolarized the RMP and reduced the instantaneous frequency of APs. TEA eliminated the effects of CPH on AP frequency and delay time, but had no effect on spike threshold or RMP. The current-voltage relationship showed that CPH increased the membrane depolarization in response to positive current pulses and hyperpolarization in response to negative current pulses, suggesting that other types of membrane ion channels might also be affected by CPH. These results suggest that CPH increases the excitability of medial prefrontal cortex neurons by regulating TEA-sensitive I channels as well as other TEA-insensitive K channels, probably I and inward-rectifier Kir channels. This effect of CPH may explain its apparent clinical efficacy as an antidepressant and antipsychotic.
Animals ; Cyproheptadine ; pharmacology ; Female ; Histamine H1 Antagonists ; pharmacology ; Membrane Potentials ; drug effects ; physiology ; Mice, Inbred C57BL ; Patch-Clamp Techniques ; Potassium Channel Blockers ; pharmacology ; Potassium Channels ; metabolism ; Prefrontal Cortex ; drug effects ; physiology ; Pyramidal Cells ; drug effects ; physiology ; Receptors, sigma ; agonists ; metabolism ; Tetraethylammonium ; pharmacology ; Tissue Culture Techniques

Mastocytosis is a disorder characterized by abnormal mast cell proliferation and accumulation in one or more tissues. It presents in two major variants: cutaneous mastocytosis and systemic mastocytosis. Because the symptoms are related to mast cells, histamine receptor antagonists and leukotriene receptor antagonists are recommended as therapeutic options. Here, we report a 54-year-old male patient with a history of urticaria pigmentosa who presented with recurrent anaphylaxis. His serum tryptase level was 31.7 ng/mL and mast cell infiltration was observed in his bone marrow. He had frequent attacks of anaphylaxis despite treatment with ketotifen, levocetirizine, and montelukast. Symptoms related to systemic mastocytosis were controlled and the patient exhibited no recurrence of anaphylaxis following the introduction of monthly omalizumab injection. Omalizumab can be considered as a treatment option in patients with systemic mastocytosis unresponsive to conventional oral medications.
Anaphylaxis ; Bone Marrow ; Humans ; Ketotifen ; Leukotriene Antagonists ; Male ; Mast Cells ; Mastocytosis ; Mastocytosis, Cutaneous ; Mastocytosis, Systemic ; Middle Aged ; Omalizumab ; Receptors, Histamine ; Recurrence ; Tryptases ; Urticaria Pigmentosa