Interaction of antidepressants and neuroleptics with histamine stimulated parietal cell adenylate cyclase and H+ secretion

The role of brain histamine in acute and chronic stresses

As a neurotransmitter or neuromodulator, brain histamine has a variety of physiological roles in brain functions. Acute stress increases the histamine turnovers in the diencephalon, nucleus accumbens and striatum. Histamine regulates anterior pituitary hormones. Anxiolytic drugs also decrease brain histamine turnover. Histamine H1 receptor antagonists and H3 receptor agonists decrease the anxiety state. These findings show that acute stresses increase brain histamine turnover, especially in the diencephalon, which would be partly related to the pathology of anxiety. Moreover, chronic restraint stress continued to increase the histamine turnovers in the nucleus accumbens and striatum, not in the diencephalon. Chronic administration of psychostimulants also increase the striatal histamine release. Histamine agonists prevent psychostimulant-induced behavior and the development of behavioral sensitization. These results indicate that chronic stress continues to increase the histamine turnovers in the nucleus accumbens and striatum, which would have a role of preventing stress vulnerability. Moreover, histamine H3 receptor antagonists have antidepressive effects. Therefore, no increase of histamine turnover in the diencephalon is related to the pathology of depressive state.

Effects of the acute and chronic restraint stresses on the central histaminergic neuron system of Fischer rat

The effects of acute and chronic restraint stresses on the brain histamine level and histamine N-methyltransferase activity in Fischer rat brain were studied. The acute restraint stress increased the histamine levels in the diencephalon and nucleus accumbens, and increased the histamine N-methyltransferase activities in the nucleus accumbens and striatum. The chronic restraint stress also increased histamine N-methyltransferase activities in the nucleus accumbens and striatum. These results indicate that the acute and chronic restraint stresses increase the brain histamine turnover, which may partly relate to the vulnerability for stress-induced anxiety and depression.

Droperidol-fentanyl inhibits mast cell histamine release in rat synovium, but not skin, after immunologic activation: evidence for mast cell heterogeneity

The characteristics of mast cell heterogeneity include differences in mast cell staining, cellular structure, content of proteoglycans and vasoactive amines, and in vitro responses to secretagogues. We have found that the anesthetic agent, droperidol-fentanyl, significantly decreased rat synovial vascular permeability after selective synovial mast cell degranulation. In contrast, there was no effect on skin mast cell-induced vascular permeability. To address the possibility that this difference in response represents mast cell heterogeneity and uniqueness of synovial mast cells, we investigated the effects of three different anesthetic agents on synovial mast cells. In these studies we examined whether (1) the drugs affect synovial mast cells and (2) whether the drugs affect synovial mast cells differently from mast cells in skin. Our data indicate that, compared to inhaled methoxyflurane and ethyl ether, subcutaneous droperidol-fentanyl had a significant inhibitory effect on synovial, but not skin, mast cell-mediated vascular permeability, which was associated with a significant inhibition of synovial mast cell histamine release. Thus, the permeability differences were not due only to effects on histamine receptors. Our data suggest the possibility that there are significant functional differences between synovial and skin mast cells, a phenomenon that may have important therapeutic implications for treatment of mast cell-mediated synovial inflammation.