TCDD (2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN) REDUCES LIPOPROTEIN-LIPASE ACTIVITY IN THE ADIPOSE-TISSUE OF THE GUINEA-PIG

TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) administered to young male guinea pigs at a dose of 1 .mu.g/kg (single i.p. injection) caused a large reduction in adipose tissue lipoprotein lipase (LPL) activity. This effect occurred rapidly; a 70% decrease was noticed after 24 h and 80% of LPL activity was lost by 48 h when the serum triglyceride levels increased to 175% of control levels. LPL plays an important role in controlling the amount of free fatty acids supplied to adipose tissues. Administration of a large dose of glucose to fasted guinea pigs, which showed a similar weight loss, but less LPL loss than TCDD-treated animals, had the effect of elevating their adipose LPL levels back to a near normal level, whereas the same treatment caused no significant increase in the LPL levels of TCDD-treated animals. The TCDD-caused decline in LPL activity is evidently irreversible. As a consequence, the affected guinea pigs are incapable of responding to changes in nutritional status.