Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Physiology

Abstract

Although ginseng has been used for centuries as a medicinal herb, little is known about the effects of North American ginseng (NAG) on the metabolic syndrome. This study was done to investigate the effects of NAG on metabolic variables, and whether central neuronal systems involved in the control of these metabolic variables were altered by NAG treatment. Experiments were done in adult male Sprague-Dawley rats fed a standard chow or a high fat (45 kcal%) diet. Animals were given NAG (250 mg/kg body weight) or vehicle (0.9% saline) daily for 4 weeks by oral gavage. Food and water intake were found not to be altered by ginseng. However, body weight, cumulative body weight gain, and fat pad mass were significantly lower in the NAG treated animals compared to the vehicle treated group regardless of diet. Similarly, NAG treatment reduced plasma leptin, insulin, triglycerides, and noradrenaline levels in all animal groups. Furthermore, NAG lowered arterial pressure and heart rate in animals fed a high fat diet. Within the central nervous system, NAG was found to induce the expression of the immediate early genes Fra-1/2 in brainstem cardiovascular regulatory centers (nucleus of the solitary tract, and caudal and rostral ventrolateral medulla), and in several hypothalamic nuclei involved in the control of the circulation and metabolism (paraventricular, arcuate, lateral, dorsomedial and ventromedial hypothalamic nuclei). Taken together, these data suggest that central brainstem and hypothalamic circuits involved in autonomic control and ingestive behaviour are altered by NAG, and suggest that the use of NAG may be effective treatment for the reduction of the risk for developing the metabolic syndrome in obesity.

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