Contribution of astrocytic histamine N-methyltransferase to histamine clearance and brain function in mice.

Brain histamine acts as a neurotransmitter in the regulation of various brain activities. Previous studies have shown that histamine N-methyltransferase (HNMT), a histamine-metabolizing enzyme, controls brain histamine concentration and brain function. However, the relative contribution of astrocytic or neuronal HNMT to the regulation of the histaminergic system is still inconclusive.

Heparan sulfate promotes differentiation of white adipocytes to maintain insulin sensitivity and glucose homeostasis.

Heparan sulfate (HS), a highly sulfated linear polysaccharide, is involved in diverse biological functions in various tissues. Although previous studies have suggested a possible contribution of HS to the differentiation of white adipocytes, there has been no direct evidence supporting this. Here, we inhibited the synthesis of HS chains in 3T3-L1 cells using CRISPR-Cas9 technology, resulting in impaired differentiation of adipocytes with attenuated bone morphogenetic protein 4 (BMP4)-fibroblast growth factor 1 (FGF1) signaling pathways.

Heparan sulfate controls skeletal muscle differentiation and motor functions.

Background: Heparan sulfate (HS) is a sulfated linear polysaccharide on cell surfaces that plays an important role in physiological processes. HS is present in skeletal muscles but its detailed role in this tissue remains unclear.

Methods: We examined the role of HS in the differentiation of C2C12 cells, a mouse myoblast cell line.

Histamine H receptor on astrocytes and neurons controls distinct aspects of mouse behaviour.

Histamine is an important neurotransmitter that contributes to various processes, including the sleep-wake cycle, learning, memory, and stress responses. Its actions are mediated through histamine H-H receptors. Gene knockout and pharmacological studies have revealed the importance of H receptors in learning and memory, regulation of aggression, and wakefulness.

Brain histamine H receptor occupancy after oral administration of desloratadine and loratadine.

Some histamine H receptor (HR) antagonists induce adverse sedative reactions caused by blockade of histamine transmission in the brain. Desloratadine is a second-generation antihistamine for treatment of allergic disorders. Its binding to brain HRs, which is the basis of sedative property of antihistamines, has not been examined previously in the human brain by positron emission tomography (PET).

Histamine elicits glutamate release from cultured astrocytes.

Astrocytes play key roles in regulating brain homeostasis and neuronal activity. This is, in part, accomplished by the ability of neurotransmitters in the synaptic cleft to bind astrocyte membrane receptors, activating signalling cascades that regulate concentration of intracellular Ca ([Ca]) and gliotransmitter release, including ATP and glutamate. Gliotransmitters contribute to dendrite formation and synaptic plasticity, and in some cases, exacerbate neurodegeneration.

Heparan sulfate in pancreatic β-cells contributes to normal glucose homeostasis by regulating insulin secretion.

Heparan sulfate (HS), a linear polysaccharide, is involved in diverse biological functions of various tissues. HS is expressed in pancreatic β-cells and may be involved in β-cell functions. However, the importance of HS for β-cell function remains unknown.

Histamine N-methyltransferase regulates aggression and the sleep-wake cycle.

Histamine is a neurotransmitter that regulates diverse physiological functions including the sleep-wake cycle. Recent studies have reported that histaminergic dysfunction in the brain is associated with neuropsychiatric disorders. Histamine N-methyltransferase (HNMT) is an enzyme expressed in the central nervous system that specifically metabolises histamine; yet, the exact physiological roles of HNMT are unknown.

JNJ10181457, a histamine H3 receptor inverse agonist, regulates in vivo microglial functions and improves depression-like behaviours in mice.

Brain histamine acts as a neurotransmitter and regulates various physiological functions, such as learning and memory, sleep-wake cycles, and appetite regulation. We have recently shown that histamine H3 receptor (H3R) is expressed in primary mouse microglia and has a strong influence on critical functions in microglia, including chemotaxis, phagocytosis, and cytokine secretion in vitro. However, the importance of H3R in microglial activity in vivo remains unknown.

Characterization of murine polyspecific monoamine transporters.

The dysregulation of monoamine clearance in the central nervous system occurs in various neuropsychiatric disorders, and the role of polyspecific monoamine transporters in monoamine clearance is increasingly highlighted in recent studies. However, no study to date has properly characterized polyspecific monoamine transporters in the mouse brain. In the present study, we examined the kinetic properties of three mouse polyspecific monoamine transporters [organic cation transporter 2 (Oct2), Oct3, and plasma membrane monoamine transporter (Pmat)] and compared the absolute mRNA expression levels of these transporters in various brain areas.

Histamine H3 receptor in primary mouse microglia inhibits chemotaxis, phagocytosis, and cytokine secretion.

Histamine is a physiological amine which initiates a multitude of physiological responses by binding to four known G-protein coupled histamine receptor subtypes as follows: histamine H1 receptor (H1 R), H2 R, H3 R, and H4 R. Brain histamine elicits neuronal excitation and regulates a variety of physiological processes such as learning and memory, sleep-awake cycle and appetite regulation. Microglia, the resident macrophages in the brain, express histamine receptors; however, the effects of histamine on critical microglial functions such as chemotaxis, phagocytosis, and cytokine secretion have not been examined in primary cells.