Sex-associated differences in pancreatic β cell function in healthy preweaning pony foals.
Authors: Jellyman J K, Valenzuela O A, Allen V L, Holdstock N B, Fowden A L
Journal: Equine veterinary journal
Summary
# Editorial Summary Pancreatic β cell function develops rapidly during early foal life and appears to be influenced by sex, with fillies demonstrating a markedly exaggerated insulin response to glucose challenges compared with colts in the immediate postnatal period. Jellyman and colleagues investigated this phenomenon by conducting intravenous glucose tolerance tests alongside arginine and tolbutamide challenges in eight fillies and five colts at 2 and 12 weeks of age, sampling blood at multiple timepoints to measure plasma glucose, insulin and amino-nitrogen concentrations. Female foals showed a significantly greater maximum insulin increment in response to glucose at 2 weeks (395 ± 58 ng/l versus 172 ± 37 ng/l in males; P<0.05), with similar sex-related differences persisting at 12 weeks, whilst responses to arginine and tolbutamide stimulation remained unaffected by sex. Since glucose clearance rates did not differ between sexes, these findings suggest that fillies may possess lower insulin sensitivity than colts during early postnatal development—a potentially important distinction given that innate metabolic differences at this critical growth window could influence tissue development trajectories and have longer-term metabolic consequences. For equine professionals, these results highlight that sex-based variation in glucose metabolism warrants consideration when evaluating metabolic development, growth rates and nutritional requirements in young stock.
Read the full abstract on PubMed
Practical Takeaways
- •Female foals may have lower insulin sensitivity than colts in early post-natal life, which could influence nutritional management and developmental programming strategies during the critical preweaning period
- •Sex-based differences in glucose metabolism appear during the first weeks of life, suggesting potential value in sex-specific feeding or monitoring protocols for young foals
- •These innate metabolic differences may have longer-term consequences for growth and tissue development, warranting further investigation into juvenile and adult health outcomes
Key Findings
- •Female foals showed significantly higher maximum insulin response to glucose at 2 weeks (395 ± 58 ng/l) compared to males (172 ± 37 ng/l, P<0.05)
- •Area under the insulin curve was significantly greater in fillies at 2 weeks of age following glucose challenge
- •At 12 weeks, insulin increment response to glucose remained significantly greater in fillies at 45 minutes post-infusion
- •β cell responses to arginine and tolbutamide were not sex-linked at either age, suggesting sex differences are glucose-specific