Ginger Rhizomes as Anti-Obesity Agent in MSG –Exposed Female Rats: Anti-Hypothyroidic Effect versus Satiety Stimulation as Possible Mechanisms

In Egypt, overexposure to monosodium glutamate (MSG) was reported as a fundamental health challenge. Thus, dietary interventions were needed to prevent the disorders associated with this food additive, especially obesity which is still of great concern. This study was conducted to investigate both the satiety stimulating and the anti-hypothyroidic properties of ginger (Zingiber officinale) as mechanisms for its anti-obesity effect in female rats concurrently exposed to MSG. Twenty adult female albino rats were divided into four equal groups, including the control group, while groups 2 to 4 were administered 6 mg MSG/kg body weight daily, and kept untreated (group 2), or concurrently fed diet supplemented with 0.5 and 1 % of ginger powder  (groups 3 and 4, respectively) for 6 weeks. At the end, body weight gain, feed intake and feed efficiency ratio were calculated. Leptin as well as thyroid –related hormones were determined in sera, while oxidative stress markers were determined in thyroid tissue homogenate. Moreover, specimens from thyroid tissue of rats were histopathologically examined. MSG consumption induced overweight along with increased appetite besides overt hypothyroidism, which was evidenced by increased thyroid stimulating hormone level (0.08±0.01 versus 0.00±0.00 uIU/ml in healthy control), while thyroxin level was decreased (2.76±0.36 versus 3.43±0.43 ng/dl in healthy control). Disturbance of antioxidant defense system in thyroid tissue was also noticed, which was further confirmed by histological staining. Inclusion of ginger powder in rat diet prevented weight gain, which was accompanied with anti-hypothyroidic effects, while appetite was not affected statistically. Thus, it could be concluded that through maintaining thyroid functions, but not reducing appetite, ginger powder prevented obesity associated with MSG consumption in female rats.