Young coconut juice increased number of calbindin and vitamin D receptor cells via estrogen receptors in gastrointestinal tract of orchidectomized rats

Adult male rats were orchidectomized, and their gastrointestinal tract was stained immunohistochemically with specific antibodies against calbindin (CB), a calcium-binding protein and vitamin D receptor (VDR), two essential factors in calcium absorption and bone formation. Compared to normal rats, the number of CB-immunoreactive and VDR-immunoreactive cells in the gastrointestinal tract were significantly reduced in orchidectomized rats, but was restored to normal by injecting these rats with estradiol benzoate or by feeding with young coconut juice (YCJ), which was found to be not dose-related. In an attempt to find out if the osteoporosis-protective effects of YCJ were due to the binding of the YCJ active component(s) with estrogen receptors, ERα and ERβ, anti-ERα and ERβ were detected immunohistochemically, and a significant correlation was detected between CB-/VDR-reactive cells vs. ERα-/ERβ-reactive cells. Immunohistochemical profiles showed significant correlations between CB-/VDR-immunoreactive cells vs. ERα-/ERβ-immunoreactive cells. The results suggest that YCJ may be as effective as estradiol benzoate in reducing osteoporosis, probably as a selective estrogen receptor moderator.