Age‐related changes in serum insulin‐like growth factor‐I, insulin‐like growth factor‐I binding protein‐3 and articular cartilage structure in Thoroughbred horses

Abstract

Summary Reasons for performing study: Structural changes in articular cartilage associated with the ageing process require definition for investigators performing developmental and age‐related studies, for which information is lacking. Objectives: To 1) determine the onset and end of puberty as defined by serum insulin like growth factor (IGF‐I) and IGF‐binding protein‐3 (IGFBP‐3) concentrations and 2) correlate articular‐epiphyseal cartilage complex structural changes with the onset and end of puberty. Methods: IGF‐1 and IGFBP‐3 were measured in serum samples from normal female and male horses age 9‐715 days to determine peak and steady‐state values for horses transitioning through puberty. Osteochondral tissue sections were obtained from horses age 120‐840 days (4‐28 months) and examined histologically for cartilage canals and tidemark formation. Results: In male and female horses, serum IGF‐1/IGFBP‐3 concentrations peaked at approximately 225 days, defining the onset of puberty. Cartilage canals were absent from articular cartilage just prior to this time point. IGF‐1/IGFBP‐3 concentrations declined to steady‐state levels at approximately age 450 days, signalling exit from puberty and therefore the beginning of ageing. This time point correlated to initial formation of a tidemark in the osteochondral tissue sections. Conclusions: Horses may be considered pubescent at age 225‐450 days, and post pubescent and ageing after age 450 days. Potential relevance: Defining the normal post natal to post pubescent concentrations for serum IGF‐I and serum IGFBP‐3 establishes subsets of animals for age‐related studies and may be used to monitor horses for abnormally high IGF‐1 concentrations due to natural disease or subsequent to systemic growth hormone administration.

A study of serum insulin-like growth factor type 1 (IGF-1) concentrations in resting untrained Andalusian horses: influence of age and gender

“…However, the progressive reduction in serum IGF-1 concentrations detected in Andalusian horses from one month of age to 10-14 years is not in agreement with the chronological evolution presented for other equine breeds. Fortier et al (2005) found high IGF-1 concentrations in Thoroughbred foals on Day 9 of age, with a decline to 7.5 months, increasing to a level comparable to neonatal concentrations and then again decreasing continuously to 15 months, after which time the concentrations remained relatively steady to 25 months of age. These authors found the peak concentrations at 8.5-10 months, whereas our peak concentrations were observed in the Andalusian foals aged 1-2 months.…”

“…These authors did not find significant differences from three to eight years of age. In Thoroughbreds, Fortier et al (2005) found the highest IGF-1 concentrations at Day 9 of age, which steadily declined to Day 224 (approximately 7.5 months). After Day 224, serum IGF-1 concentrations increased to a level comparable to neonatal concentrations, and then again decreased continuously to Day 450 (approximately 15 months), after which time they remained relatively steady to Day 715 (approximately 31.8 months).…”

“…On the other hand, Tremblay et al (1993) found that Standardbred horses had higher circulating IGF-1 concentrations than Thoroughbreds. Serum IGF-1 concentrations have been reported in horses of different breeds, such as Thoroughbreds (Ozawa et al, 1995;Jackson et al, 2003;Fortier et al, 2005;Noble et al, 2007), Standardbred trotters (Malinowski et al, 1996;Champion et al, 2002), Belgian-cross and Quarter Horse-draft cross (Cymbaluk and Laarveld, 1996) and Quarter Horses (Ropp et al, 2003). To the authors' knowledge, the studies concerning comparative interbreeds are more limited (Tremblay et al, 1993;Ozawa et al, 1995;Cymbaluk and Laarveld, 1996).…”

“…Serum IGF-1 concentrations in horses depend on many factors, such as breed (Tremblay et al, 1993;Ozawa et al, 1995), age (Malinowski et al, 1996;Champion et al, 2002;Fortier et al, 2005;Noble et al, 2007;Munoz et al, 2010a), sex (Ozawa et al, 1995), nutritional status, particularly dietary protein supply and feed deprivation and refeeding (Sticker et al, 1995;Christensen et al, 1997;Ropp et al, 2003), exercise, training and fitness level (Jackson et al, 2003;Noble et al, 2007).…”

Effects of platelet‐rich plasma on the quality of repair of mechanically induced core lesions in equine superficial digital flexor tendons: A placebo‐controlled experimental study

“…Cross-reaction of the antibodies in these human kits with equine samples had been demonstrated previously, 28,29 or has been assumed on homology between equine and human protein structure. Glycosaminoglycans and DNA Analysis After lyophilizing for 24 h and recording dry weight, the tendon samples were papain digested.…”