Serum Insulin-Like Growth Factor (IGF)-I Concentrations Are Reduced by Short-Term Dietary Restriction and Restored by Refeeding in Domestic Cats (Felis catus)

Abstract

Nutritional modulation of insulin-like growth factors (IGF) and their binding proteins (IGFBP) is well established. The effect of nutritional restriction on the serum IGF/IGFBP system of adult cats was investigated to evaluate serum IGF-I as a biochemical marker of nutritional status. Assays for measuring feline serum IGF and IGFBP were validated and normal ranges established in a study population of 46 healthy nonobese adult cats. Serum concentrations of IGF-I and IGF-II correlated significantly with body weight (r = 0.75, P < 0. 0001 and r = 0.34, P < 0.03, respectively). Serum IGFBP profiles were similar to other species, including humans, dogs and guinea pigs. IGFBP-3 was the predominant binding protein reflecting IGF-I concentrations and body size. Serum IGFBP-2 concentrations were high relative to the normal human serum pool (NHS) control. Food withdrawal for 18 h followed by refeeding did not alter circulating IGF or IGFBP concentrations, including IGFBP-1, in nine cats. Short-term dietary restriction of nine adult cats to supply initially 56% (56%M) and then 42.5% (42.5%M) of calculated maintenance energy requirements for 14 d resulted in a significant weight loss (P < 0.01). However, serum IGF-I concentrations fell significantly (-51%, P < 0.01) only with 42.5%M restriction. Serum IGF-II, IGFBP, insulin and albumin concentrations were not altered during the study. We conclude that nutrition does modulate the adult feline IGF/IGFBP system, but to a lesser extent than in other species. Further evaluation is required before serum IGF-I can be used for the assessment of nutritional status in adult cats.

Evaluation of IGF-I levels and serum protein profiles of diabetic cats and dogs

“…A 29 kDa band has been previously identified as IGFBP-1 in cats by immunoblotting [25]. In our study, the density of 29 kDa protein band was found as decreased in insulin-treated cats whereas the density of 25 kDa protein band increased in diabetic compared to insulin-treated cats.…”

“…Four of these are important in human serum (IGFBP-1 to 4) in which IGF-I is predominantly bound to IGFBP-3 [32]. On the other hand, a previous study [25] reported that IGFBP-3 appears as doublet (39 and 43 kDa) in cats. Lewitt et al [22] has also reported that cat serum contains IGFBP-3 doublets bands with molecular masses of approximately 45 kDa and 25~35 kDa.…”

Pasireotide for the Medical Management of Feline Hypersomatotropism

“…None of the enrolled cats had evidence of impaired liver or kidney function on these blood tests. We closely monitored food intake during the study because short‐term fasting can decrease serum IGF‐1 concentration in cats . Fortunately, none of the cats in the study experienced noticeable decrease in caloric intake during hospitalization.…”

Evolution of blood parameters during weight loss in experimental obese Beagle dogs

“…Serum IGF-I concentration is generally considered as a biochemical marker of nutritional status and correlates significantly with BW in cats and dogs (Eigenmann et al, 1984;Maxwell et al, 1999). Because normally IGF-I levels reflect the growth hormone (GH) status and because GH secretion is decreased in obesity, it has been suggested that IGF-I is stimulated by the hyperinsulinism that is very often present in the obese state (Clemmons and van Wyk, 1984).…”

“…Because normally IGF-I levels reflect the growth hormone (GH) status and because GH secretion is decreased in obesity, it has been suggested that IGF-I is stimulated by the hyperinsulinism that is very often present in the obese state (Clemmons and van Wyk, 1984). Furthermore, IGF-I is reduced by fasting or by short-term dietary restriction in cats (Maxwell et al, 1999). In the present trial, we did not observe significant variations of IGF-I, nor insulin concentrations during the weight loss programme.…”