AJP - Endocrinology and Metabolism, Vol 263, Issue 5 E920-E927, Copyright © 1992 by American Physiological Society
Early metabolic consequences of epidermal growth factor administration to neonatal rats
M. M. Donnelly, S. B. Hoath and W. F. Pickens
Department of Pediatrics, University of Cincinnati, Ohio 45267-0541.
Daily administration of epidermal growth factor (EGF) to neonatal rodents
elicits a classic morphogenetic syndrome. In this study, we examined the
early (minutes to hours) consequences of EGF treatment in the neonatal rat
(age 0-72 h). Significant findings included a rapid reduction in resting
heart rate 4 h after EGF treatment accompanied by a sensitive dose- and
age-dependent decrease in systemic oxygen consumption (VO2). Midscapular
skin temperature (MST) was measured as a putative noninvasive indicator of
brown adipose tissue thermogenesis. As little as 10 ng EGF/g body wt
elicited a significant reduction in MST. Both the decrease in VO2 evoked by
EGF and the MST response were potentiated by environmental cold exposure.
EGF treatment also resulted in rapid (90 min) reductions in circulating
levels of glycerol, triglyceride, and cholesterol while increasing serum
glucose and arachidonic acid. Other free fatty acids were unaffected. Serum
lactate levels were increased by EGF with the same time course as the
reduction in VO2. These results provide new biochemical data on the
pharmacological actions of EGF and further characterize the EGF-treated
neonatal rodent as an intriguing in vivo model of growth factor action.
