Zhi-Li Huang (#,+), Takatoshi Mochizuki (#), Hirokazu Watanabe and Kazutaka
Maeyama (*)
Department of Pharmacology, Ehime University School of Medicine, Shigenobu-cho,
Onsen-gun, Ehime 791-0295, Japan
(#) Present address: Department of Molecular Behavioral Biology, Osaka Bioscience
Institute, 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan.
(+) Visiting scholar from Department of Pharmacology, Wannan Medical College,
Wuhu, Anhui 241001, P.R. China.
(*) To whom correspondence should be addressed.
Abstract: The effect of immobilization, gentle handling and decapitation
on the level of plasma histamine in Wistar rats was investigated. Mast cell
deficient (Ws/Ws) rats were used to characterize the source of elevated
histamine in plasma by stress, and the effect of nedocromil, a mast cell
stabilizer, on histamine release was assessed in these models in vivo. The
plasma histamine concentration of freely moving rats was 93.0+/-2.3 pmol/ml.
Gentle handling produced a transient increase in plasma histamine level
by 1.9-fold,
whereas immobilization resulted in a longer-lasting elevation by 2.6-fold
compared to that in the freely moving rats. Decapitation increased the plasma
histamine level by 10- to 16-fold compared with that in the freely moving
rats. No increase in plasma histamine was found in Ws/Ws rats exposed to
stress. Nedocromil inhibited the increase in plasma histamine level induced
by stress in a dose-dependent manner. These findings suggest that stress
induces histamine release from mast cells in Wistar rats and the extent
of this histamine release increases with the severity of stress. Nedocromil
proved to be a good pharmacological tool to inhibit stress-induced release
of mediators from mast cells.
Keywords: Immobilization stress, Gentle handling, Decapitation, Histamine
release, Nedocromil