Really does temperature reduction and norepinephrine have similar effects on the energy metabolism in rat brown adipose tissue?

CONTEXT

Heat generation by brown adipose tissue (BAT) in response to temperature reduction seems to be entirely related to sympathetic nervous stimulation.

OBJECTIVE

To analyse if temperature reduction and norepinephrine may differently affect the expression of proteins related to energy metabolism in BAT.

MATERIALS AND METHODS

Isolated rats BAT was incubated with/without norepinephrine (10 mol/L, 24 h at 32 °C and 37 °C).

RESULTS

In BAT, 32 °C increased the protein expression levels of carnitine palmitoyltransferase-I and -II, mitochondrial uncoupling protein-1 (UCP-1) and the expression and activity of lactate dehydrogenase. Mitochondrial F-ATP synthase α-chain expression was decreased at 32 °C compared to 37 °C. Norepinephrine and at 32 °C exposure, UCP-1 expression was increased but cytochrome-c oxidase and F-ATP synthase α-chain expression was reduced with respect to 37 °C.

DISCUSSION

Sympathetic stimulation seems not to be the only factor associated with heat generation.

CONCLUSIONS

Temperature reduction by itself exerts some different effects on the expression of proteins related to the energy metabolism than norepinephrine.