Adrenergic blockade paradoxically increases lipogenic response of brown adipose tissue to sympathetic nerve stimulation.

Intermittent electrical stimulation of sympathetic nerves entering the interscapular brown adipose tissue (BAT) in rats increased the rate of glyceride glycerol synthesis in BAT but the fatty acid synthesis did not change. Simultaneous administration of phenoxybenzamine and propranolol paradoxically increased the fatty acid synthesis in response to the nerve stimulation whereas the glyceride glycerol synthesis was inhibited. Propranolol alone was also effective in mimicking the effects of adrenergic blockade, but guanethidine selectively eliminated the lipogenic response to the nerve stimulation. These results indicate that synthesis of glyceride glycerol induced by sympathetic nerve stimulation is largely due to beta-adrenergic action of noradrenaline, whereas synthesis of fatty acids may be mediated by non-adrenergic transmission of the sympathetic nerves.