Background. Itch can be transmitted by two parallel pathways, histaminergic and nonhistaminergic. Histaminergic itch is a subgroup of mechano-insensitive C-fibers, while nonhistaminergic polymodal C-fibers. Experimental models are used to study pruritus: histamine for the antagonizing H1-receptors, BAM8-22 cowhage activating Mas-related G protein-coupled receptors protease-activated receptors, ...

The aim of the present study was to investigate whether and by which mechanism; histamine can induce state-dependent retrieval of passive avoidance task. The pre-training or pre-test intracerebroventricular (i.c.v.) injection of histamine (20µg/mouse) impaired retrieval, when it was tested 24 h later. In the animals, which retrieval was impaired due to histamine pre-training administration, pre...

Histamine has positive inotropic and chronotropic effects on the heart which are not abolished by beta adrenergic-blocking agents. Since the positive inotropic and chronotropic effects of other hormones on the heart are thought to be mediated by cyclic 3',5'-AMP, we examined the effect of histamine on adenyl cyclase in particulate preparations of guinea pig, cat, and human myocardium. Histamine...

BACKGROUND Histamine is the prototypical pruritogen used in experimental itch induction. However, in most chronic pruritic diseases, itch is not predominantly mediated by histamine. Cowhage-induced itch, on the other hand, seems more characteristic of itch occurring in chronic pruritic diseases. OBJECTIVES We tested the validity of cowhage as an itch-inducing agent by contrasting it with the ...

A previous paper (Marks, 1957) describes work done on a number of substances to ascertain their protective effect on phagocytic cells in tissue culture against injury by silica dust. The most potent of those investigated was 48-80, a drug used in experimental pharmacology to release histamine from mast cells. In the present paper, several drugs related to compound 48-80 have been examined for t...

conclusions cyclosom and histamine synergistically exert catalepsy in old rats. in light of these data, the combination of the decreased brain level of somatostatin and increased brain level of histamine may be of pathogenic relevance for extrapyramidal signs in pd. results cyclosom (0.2, 1.0, and 5.0 µg) and histamine (1.0 and 10.0 µg) alone were ineffective in both young and old animals. in c...

Changes characteristic of an inflammatory reaction caused by the injection of an injurious agent into the peritoneal cavity were measurable by the quantity of peritoneal fluid, by the number of leucocytes that entered the cavity, and by the abundance of exuded protein. Inflammation increased in severity along with ion dissociation and increase of the valence of electrolytes. With chlorides, sul...

The role of personal factors makes it difficult to correlate subjective data, such as those obtained with the use of a visual analogue scale, and objective data, such as a quantity of injected histamine. In this study, prick tests with histamine and codeine on the forearms allowed a coherent variation in itch scores to be obtained over time, with highly significant differences from controls and...

Cowhage and histamine, both applied via spicules, were used to induce itch. The quality and intensity of the sensations, axon reflex flare, sympathetic skin vasoconstrictions and the interference of scratching with itch processing were studied. Axon reflex flare reactions were measured by laser Doppler imaging and reflex vasoconstrictions in the finger were recorded by laser Doppler flowmetry. ...