The Response of Hairless Mice to Long-term Serotonin Administration

Abstract

The effects of long-term serotonin administration in animals are not well-known. The increasing interest in the function of serotonin, and its possible relationship to connective tissue disorders, necessitates study of such effects. One of the many theories of serotonin function is that it is a fibrosing agent. MacDonald, Robbins and Mallory (4) found that long-term subcutaneous injections of serotinin resulted in a collagenous and fibrous proliferation in the dermis of the rat, with hyperplastic changes of the epidermis. Scherbel, McKittrick and Hawk (7), studying the response to subcutaneously implanted Ivalon sponges in rats, reported that large and un-physiological doses of serotinin increased inflammation, but impeded rather than stimulated connective tissue growth. Lapiere (3) also studied the connective tissue response around implanted Ivalon sponges, following repeated local inject-tions of serotonin. He found an increase in the soluble forms of collagen and felt that this indicated an increased activity of fibroblasts. There are only a few reports concerning the systemic effects of injected serotonin. Waugh and Beschel (8) studied the effects on rat kidney. They found that serotonin injected intraperitoneally produced variable degrees of necrosis of the distal and convoluted tubules, and concluded that the nephropathy effects were due to vasospastic ischemia. The purpose of the present study was to study fully the effects of long-term administration of serotonin to hairless mice, both at the site of administration and systemically.