21.   Other investigators proposed that in rare cases the drugs might paradoxically produce a drop in serotonin levels.

22.   Prozac alleviates depression by increasing serotonin levels.

23.   Serotonin levels affect mood, sexual desire, digestion, depression, and, apparently, REM sleep.

24.   The company counters that the doses used in people will be somewhat lower than those used in animals and that in humans the serotonin levels rise back to normal.

25.   The sugar increases serotonin levels in the brain, and serotonin is the feel-good hormone.

26.   This receptor senses when serotonin levels are on the rise, and like a rheostat on a heater, signals the neuron to slow down its serotonin secretion.

27.   And lowering serotonin levels in cats has also been shown to induce male homosexual activity, they noted.

28.   Depletion of tryptophan in rats and rabbits has been shown to lower serotonin levels and trigger male sexual mounting.

29.   Serotonin levels already have been linked to depression, migraine headaches and irritable bowel syndrome.