Seirogan, a wood
creosote, has been used as an antidiarrhetic
drug in Asian countries including Japan for many years. This antidiarrhetic has recently been used as a
sugar-coated pill because
Seirogan has a strong smell. The strong smell of the uncoated form of
Seirogan may modulate the defense systems of animals because the sense of smell is important for the detection of toxic metabolites in foods contaminated with pathogens. This study examined the effect of the
sugar-coated and uncoated forms of this antidiarrhetic on the immunological response and inflammatory reactions in mice that had been sensitized with either
fluorescein isothiocyanate or
oxazolone. The sensitization of mice with either
FITC or
oxazolone markedly increased the plasma levels of
tumor necrosis factor-α and mucosal
IgA and elicited severe
inflammation in the colon by a mechanism that could be suppressed by exposure of animals to the smell of uncoated
Seirogan as effectively as the
oral administration of the agent. Dermal
inflammation in the
FITC- and
oxazolone-sensitized mice was also suppressed effectively either by the exposure to the smell or
oral administration of the agent. Biochemical and histochemical analyses revealed that the elevated levels of plasma
tumor necrosis factor-α and mucosal
IgA were significantly decreased by exposure to the smell of uncoated
Seirogan as well as by
oral administration of the agent. Exposure of mice to the smell of
Seirogan but not
oral administration of the agent selectively increased plasma levels of
adrenocorticotropic hormone and
cortisol, particularly in the sensitized animals. These observations suggest that exposing the animals to the smell of
Seirogan per se activated the hypothalamo-pituitary-adrenal axis and systemically modulated immunological reactions to suppress the
allergic reactions.