Alterations in rat adipose tissue morphology induced by a low-temperature environment.

Rats raised in the cold showed an unusual pattern of adipose tissue morphology. Male Sprague-Dawley rats were maintained in a 5 degrees C environment for up to 24 wk and the cellularity of their major adipose depots was determined. Normal age-related increases in adipocyte number were absent in two major fat depots (retroperitoneal and inguinal), whereas there was a supranormal increase in a third (epididymal). This pattern of hyperplasia contrasts sharply with that seen in rats fed highly palatable high-fat or high-carbohydrate diets in which retroperitoneal depots show the most hyperplasia and epididymal pads the least. Such variations of response across depots suggest that the features of adipose tissue responsible for adipocyte proliferation in the various depots may not be homogeneous both in their nature and in their distribution.