Abstract
In rat epididymal tissue in vitro, calcitonin had an anti-lipolytic effect, measured
as a depressed glycerol release into the incubation medium. In particular basal lipolysis
was affected, but the antilipolytic effect of calcitonin could also be demonstrated
during slightly stimulated lipolysis with parathyroid hormone, noradrenaline or dibutyryl
cyclic AMP. During marked and maximal stimulation of lipolysis no antilipolytic effect
of calcitonin was noted.
The accumulation of calcium in the fat tissue, previously shown to increase with
increasing lipolysis, was also depressed by calcitonin. This depression, in contrast
to the antilipolytic effect of calcitonin, became more significant with increasing
lipolysis.
The antilipolytic effect of calcitonin was maintained after adrenalectomy, while
during in vivo glucocorticoid excess it was diminished, seemingly due to decreased
tissue sensitivity. Calcitonin did not modify the highly significant decreased calcium
accumulation in the tissue, seen after adrenalectomy, or the increased calcium accumulation
noted after injections of high doses of cortisone acetate.
The results indicate that calcitonin may have a cyclic AMP-dependent effect on lipolysis,
which is not primarily interference with the hormonal activation of adenylate cyclase
activity as basal lipolysis is affected. The effect of calcitonin on calcium accumulation
seems to be independent of the adenylate cyclase-cyclic AMP system as it is demonstrable
during direct lipase activation by dibutyryl cyclic AMP.
The two noted effects of calcitonin are discussed with special reference to known
effects of two other antilipolytic substances, insulin and nicotinic acid.
Key words
Calcitonin - Lipolysis - Calcium - Adrenalectomy - Cortisone-acetate
