Distribution of oleyl-anilide hydrolysing activity in rat and human tissues

A method has been developed and tested for the measurement of anilide hydrolysing activity in rat tissues. A concentrated solution of labelled oleyl anilide in isopropanol is added to the tissue homogenates and after incubation, the chloroform/methanol extract of the samples is chromatographed on Silicagel TLC plates and the oleic acid radioactivity is measured. The activity is time-, homogenate- and temperature-dependent, the optimal pH for measurement is 8 and there is no significant spontaneous anilide degradation. In the rat, the activity is widely distributed, with highest protein specific activity in the adipose tissues. The tissue activities of a same animal are fairly well inter-correlated, with rats showing very low activity in all tissues compared with others presenting high overall activity. The levels of activity found can easily explain the fast elimination of anilides administered to rats and their scant toxic effects. Human adipose tissue samples showed a wide range of anilide hydrolase activities per gram of protein, in general lower than in rats and with some values very low. It is postulated that this lack of anilide-hydrolising capability in some humans may be related to the incidence of the toxic oil syndrome.