Effects Of Rice Bran Arabinoxylan Compound On Intense Exercise-induced Secretory Immunoglobulin A Suppression In Rats.

Abstract

Secretory immunoglobulin A (SIgA) plays a major role in specific immunity and provides a protection at mucosal surfaces via several mechanisms. Polymeric immunoglobulin receptor (pIgR) on the surface of the epithelial cells combines with immunoglobulin A to form SIgA. Intense exercise causes a functional decline in several components of the immune system. Rice Bran Arabinoxylan Compound (RBAC; Daiwa Pharmaceutical Co., Ltd.) is obtained by reacting rice bran hemicellulose with multiple carbohydrate hydrolyzing enzymes from. Lentinula edodes mycelia and seems to act as a potent biological response modifier. PURPOSE: To evaluate the effects of RBAC supplementation on the SIgA in rat saliva and on inhibitory effect of intense exercise-induced SIgA suppression. METHODS: Male Wistar rats (8 weeks of age) were assigned to one of the following treatment groups: (1) RBAC-Ex, a RBAC ingested exercised group (n=7); (2) RBAC-Sed, a RBAC ingested sedentary group (n=6); (3) DW-Ex, a distilled water ingested exercised group (n=7); (4) DW-Sed, a distilled water ingested sedentary group (n=6). Rats received RBAC (150 mg/kg body weight) or distilled water orally for two weeks. Their saliva was collected before (0w), after 1 week (1w), 2 weeks (2w) of RBAC intake, and before (pre) and after (post) exercise; the salivary glands were removed after exercise. SIgA concentration in saliva was measured by ELISA, and pIgR mRNA expression in the salivary glands was analyzed by the 7500 Fast Real Time PCR System. RESULTS: Treatment with RBAC significantly increased SIgA concentration (0w: 6.27 ± 0.37 vs. 2w: 9.82 ± 1.79 μg/ml, p<0.05), while there was no significant change in the DW groups. SIgA in the RBAC-Ex and DW-Ex groups significantly decreased after exercise compared with before (p<0.05). The expression of pIgR mRNA did not show significant difference between RBAC-Ex and DW-Ex groups. CONCLUSION: RBAC supplementation for two weeks enhances saliva SIgA concentration, and it may be a potent biological response modifier for exercise-induced immune suppression. Supported by Daiwa Pharmaceutical Co., Ltd.