Administration of
green tea or
caffeine was shown previously to inhibit ultraviolet B light-induced
carcinogenesis in SKH-1 mice, and this effect was associated with a reduction in dermal fat. In the present study,
oral administration of 0.6%
green tea (6 mg
tea solids/ml) or 0.04%
caffeine (0.4 mg/ml; equivalent to the amount of
caffeine in 0.6%
green tea) as the sole source of drinking fluid to SKH-1 mice for 15 weeks increased total 24 hr locomotor activity by 47 and 24%, respectively (p<0.0001).
Oral administration of 0.6% decaffeinated
green tea (6 mg
tea solids/ml) for 15 weeks increased locomotor activity by 9% (p<0.05). The small increase in locomotor activity observed in mice treated with decaffeinated
green tea may have resulted from the small amounts of
caffeine still remaining in decaffeinated
green tea solutions (0.047 mg/ml). The stimulatory effects of orally administered
green tea and
caffeine on locomotor activity were paralleled by a 38 and 23% increase, respectively, in the dermal muscle layer thickness. In addition, treatment of the mice with 0.6%
green tea or 0.04%
caffeine for 15 weeks decreased the weight of the parametrial fat pad by 29 and 43%, respectively, and the thickness of the dermal fat layer was decreased by 51 and 47%, respectively. These results indicate that
oral administration of
green tea or
caffeine to SKH-1 mice increases locomotor activity and muscle mass and decreases fat stores. The stimulatory effect of
green tea and
caffeine administration on locomotor activity described here may contribute to the effects of
green tea and
caffeine to decrease fat stores and to inhibit
carcinogenesis induced by UVB in SKH-1 mice.