Recovery of the erg in n-3 deficient guinea pigs following dietary repletion

Purpose: To determine the existance and nature of a critical period, with respect to electroretinographic (ERG) functional recovery in docosahexaenoic acid (DHA) deficient guinea pigs (GP), repleted with n-3 sufficient diet, supplemented with canola oil (CO). Methods: Albino GP's of the Duncan-Hartley strain were raised from weaning on a semi-synthetic premixture, supplemented with either saffiower seed oil (SO, n-3 deficient) or CO (n-3 sufficient). Investigation of a critical period was conducted by repleting SO GP's with CO. Animals were repleted at 6 weeks post-weaning for 5 or 10 weeks, or at 11 weeks post-weaning for 5 weeks. Hence animals were raised to 6, 11 or 16 weeks post-weaning, with ERG data collected at various time points, including all diet change points. Retinal phospholipid fatty acids (PLFA) were measured by GLC at the time of sacrifice. Results: Electroretinographic resposes of SO animals worsened as the animals aged, corresponding to a reduction in the level of DHA in the retina. The retinal PLFA profile was markedly affected by dietary repletion, regardless of the age that this commenced. Functional recovery (ERG) was observed in repleted groups, and reflected the increased level of DHA in the retina, which approached that found in n-3 sufficient animals, raised from weaning on the CO diet. Conclusion: At the gross functional level assessed with the ERG, retinal dysfunction due to n-3 deficiency appears to be reversible by dietary repletion, and possibly open-ended in terms of a critical period.