The effect of repeated tryptophan administration on body weight, food intake, brain lipid peroxidation and serotonin immunoreactivity in mice

Abstract

Tryptophan as a circulating precursor of serotonin (5-HT) may suppress food intake and body weight. Tryptophan administration can enhance the generation of reactive oxygen species (ROS) by inducing oxidative pathway in vivo and in vitro. We have examined the effect of repeated tryptophan administration on food consumption, body weight, brain lipid peroxidation and 5-HT immunoreactivity. Tryptophan was given at the dose of 100 mg/kg/24 hr in 0.2 ml saline solution i.p. for 7 days to mice. Control mice received 0.9% NaCL solution at the same manner and volume. Body weights were recorded at the beginning and end of the experiments. Thiobarbituric acid reactive substance (TBARS), the last product of lipid peroxidation, was measured spectrophotometrically. Brain 5-HT levels were determined by the immunohistochemical method. Our findings indicate that the tryptophan suppresses food intake significantly in mice. Body weight decreased and brain TBARS levels increased significantly by repeated tryptophan treatment. Immunohistochemical detection showed that 5-HT levels increased by tryptophan administration. There is a link between increased 5-HT level and oxidative stress by tryptophan administration on brain tissue. Tryptophan at repeated doses should be exercised carefully in clinical practice.

Food-derived serotonergic modulators: effects on mood and cognition

“…However, a 7 d Trp treatment in mice suppressed food intake significantly and, more worryingly, increased brain thiobarbituric acid-reactive substances (a measure for oxidative stress) (118) . Taken together, these data show that it might be worthwhile to investigate whether the positive effects of ATS in human subjects could be maintained when diet is supplemented with Trp over a longer period of time.…”

Genome-wide associations for feed utilisation complex in primiparous Holstein–Friesian dairy cows from experimental research herds in four European countries

“…Tryptophan is an essential amino acid that cannot be produced in the body. For that reason, tryptophan is well investigated and linked to feed intake in humans (Wolfe et al, 1997), cattle (Choung and Chamberlain, 1992), mice (Coskun et al, 2006) and pigs (Montgomery et al, 1980). As discussed by Koopmans et al (2006), tryptophan serves as the immediate precursor to serotonergic activity in the brain, and has been implicated in the regulation of many behavioural and physiological processes such as mood, aggression, susceptibility to stress, sleep patterns, but also the regulation of feed intake.…”

Effects of rumen-protected tryptophan on growth performance, fibre characteristics, nutrient utilization and plasma essential amino acids in Cashmere goats during the cashmere slow growth period

“…Meanwhile, in rats, Trp supplementation has been reported to increase growth rate significantly without altering food intake (Haider et al, 1999). Diets containing high Trp levels have been observed to suppress food intake and to decrease BW in mice (Coşkun et al, 2006). The present results indicated that 2.0 g/day RPT supplementation in a Cashmere goat diet can adequately meet optimal dietary requirements; growth performance was not further improved by a higher supply of RPT.…”