ABSTRACT
The concept of a physiological or pharmacological response to sympathetic nerve stimulation and sympathomimetic amines being the result of an interaction between an agonist molecule and a receptor was developed with little knowledge of the nature of these receptors or that even existed. The approaches used in the classification of adrenoceptors and their subclassification are described. The first step towards identifying adrenoceptors was the development of radioligand binding techniques. Lipolysis, the breakdown of triglycerides to free fatty acids and glycerol by the action of hormone-sensitive lipase, occurs in adipocytes of white (WAT) and brown adipose tissue (BAT). The sympathetic activity to BAT increases and there is an elevated thermogenic response to noradrenaline. This activation can be prevented by sympathetic denervation. There is good evidence that the adipocytes of BAT receive a rich innervation compared with WAT.
