Researchers have been investigating alpha-endorphin since the 1970s, but are still not sure exactly how the polypeptide works or how it specifically affects the body. It is known, however, that alpha-endorphin contains 16 amino acids, only one less than gamma-endorphin, from which it may be formed. The seemingly small alteration of the substance, however, is apparently accompanied by a significant change in the influence the polypeptide has on the body. Studies have yet to reveal the exact nature of these changes, but some scientists have suggested that alpha-endorphin may stimulate the brain in a manner similar to amphetamines, while others indicate that gamma-endorphin originates at times from cells of the stomach and may help treat anaphylactic shock and similar conditions.