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Diurnal Distribution of Motor Activity and Feeding during Growth of Tumors

Laboratory of Physiology, National Cancer Institute, NIH, Bethesda, Maryland 20014

The diurnal distributions of motor activity and feeding were examined as indicators of hypothalamic function in three host-tumor organisms: (a) Sprague-Dawley-Walker 256 carcinosarcoma, (b) Sprague-Dawley-4M carcinoma, and (c) Buffalo-5123 hepatoma. The normal, high night/day activity ratio was depressed with growth of tumor in b, but there was no significant change in a and c. The normal, high night to day feeding ratio was depressed with growth of tumor in a, reduced to one in b, and slightly enhanced in c. Changes in diurnal ratios preceded decline in total daily food intake and motor activity. Magnitudes of diurnal ratios of activity and feeding were unrelated in non-tumor-bearing animals. Immediately upon initiation of growth of all tumors, the two ratios became significantly correlated, even when there was no significant change in average magnitude. Hypothalamic dysfunction may be slightly but variably involved in cachectic hypophagia.

Received 11/29/73. Accepted 3/27/74.