Serum insulin-like growth factor binding proteins (IGFBPs) as markers for anabolic/catabolic condition in fishes

In fishes as well as in all Vertebrates in which it has been assessed, phys iological shifts toward catabolism (e.g. uch as during food deprivation) ar e consistently associated with elevations in the serum levels of at least o ne (often two in fishes) IGFBP in the less than or equal to 31-kDa size ran ge. In mammals, 30-kDa IGFBP-1 is strongly up-regulated under catabolic cir cumstances, and it plays an important physiological role by sequestering IG F peptides to inhibit energy-expensive growth until conditions are more fav orable (e.g, with resumed feeding). Similarly in fishes, it has been found that when the less than or equal to 31-kDa IGFBPs are elevated in serum, so matic growth is inhibited, suggesting a similar growth-inhibitory role of t hese proteins to that of mammalian IGFBP-1. Three different experimentally- induced catabolic states in fishes are compared in this paper: fasting; ins ulin-dependent diabetes mellitus (IDDM); and stress. A strong relationship between elevated serum cortisol concentrations and the presence of IGFBPs i n each case is noted, and the utility of serum IGFBP measurement to serve a s an effective indicator (marker) of catabolic condition in fishes is discu ssed. (C) 2001 Elsevier Science Inc. All rights reserved.