STIMULATORY EFFECT IN VITRO OF PROSTAGLANDIN E1ON NORADRENALINE‐INDUCED LIPOLYSIS IN SUBCUTANEOUS ADIPOSE TISSUE FROM HYPOTHYROID SUBJECTS

Abstract.The lipolytic action of noradrenaline in vitro is markedly reduced in subcutaneous adipose tissue of hypothyroid subjects. This is due to an increased responsiveness of the alpha adrenergic receptors to noradrenaline, resulting in the suppression of the lipolytic effect of the hormone mediated by the beta receptor. Prostaglandin E1(PGE1) inhibited noradrenaline‐induced lipolysis in euthyroid subjects. In contrast, PGE1significantly stimulated the lipolytic action of noradrenaline in adipose tissue from hypothyroid subjects. This has been interpreted as an inhibitory effect of PGE1upon alpha as well as upon beta adrenergic receptor responses to cate‐cholamines. In tissues from euthyroid subjects the main effect of PGE1was an inhibition of the beta adrenergic response to noradrenaline. In adipose tissue from subjects where alpha receptor responsiveness dominates, the action of PGE1mainly results in alpha receptor inhibition.