The dose – dependent effects of Aspartame on Serotoninergic Parameters in Albino Rats
Scientific evidence to validate anecdotal claims that aspartame (ASP), a low
calorie sweetener may modulate Serotoninergic mediated behaviours remains
inconclusive. This study determined the effects of ASP on plasma tryptophan,
serotonin, monoamine oxidase (MAO) activity and platelet aggregation in rats
intraperitoneally administered with 40, 100 and 200 mg/kg doses over 14 days.
The sweetener induced dose – dependent decreases in MAO activity (9.27 – 4.16
unit/ml vs. 11.4 units/ml) and plasma levels of tryptophan (10.4 – 5.8 mM vs.
14.7 mM) and platelets serotonin (7.3 – 2.6ng/ml vs. 8.6ng/ml) when compared to
the control with ASP200 eliciting significant effects (P < 0.05). ASP100 and
ASP200 further caused moderate (1.95 + 0.2ng/ml vs. 1.30 + 0.07ng/ml, P > 0.05)
and significant (P < 0.05) elevation in free plasma serotonin in the
experimental animals. The increased platelet aggregation induced by ASP200
associated strongly with platelets serotonin level (r = - 0.63; P < 0.05) but
weakly with plasma free serotonin (r = 0.14; P > 0.05). The results of this
study have provided a strong indication that aspartame may alter serotoninergic
parameters and associated behaviours when consumed at doses greater than
100mg/kg per day. The healthiness inherent in acceptable daily intake compliance
of aspartame in foods, candies and beverages is discussed.