The Effect Of High-intensity Interval Training On Cerebrum Bdnf Level In Postnatal Growth-restricted Mice

Scientific literature has demonstrated that growth-restricted mice do not respond positively to exercise when examining striated muscles (cardiac and skeletal). Exercise positively affects brain health and is suggested to mitigate neurodegenerative due to brain-derived neurotrophic factor (Bdnf). Furthermore, high-intensity interval training (HIIT) has been proposed as a possible method to elicit positive exercise responses from postnatal growth-restricted (PNGR) mice. PURPOSE: To determine the effect of HIIT on PNGR Bdnf level in mouse cerebrum. METHODS: Growth-restriction was induced using a cross-fostering nutritive model whereby FVB mice pups born to dams fed a 20% protein diet were cross-fostered to dams fed an 8% protein diet to induce PNGR (n = 18). An additional cohort of pups born to dams fed a 20% protein diet were cross-fostered to a different set of dams fed 20% protein diet (CON, n = 17). The 8% protein diet reduces milk production during lactation, causing PNGR. At PN 21, all pups were weaned, fed a 20% protein diet, and were assigned to either a HIIT group (TRD, CON female n = 5, CON male n = 4, PNGR female n = 4, PNGR male = 5), or a sedentary group (SED, CON female n = 4 CON male n = 4, PNGR female n = 4, PNGR male = 5). At PN 45, a maximal exercise performance test was conducted to set HIIT intensities. From the maximal exercise performance test, mice performed treadmill HIIT running 5 days/week for 4 weeks with alternating intervals of 8 mins at 85% and 2 mins at 50% maximal exercise capacity for 60 minutes. At PN 70, all mice were euthanized, cerebrum tissue was collected, and Bdnf protein expression was analyzed by western blot. ANOVA was used to compare Bdnf protein level, followed by a Tukey’s HSD post-hoc test. RESULTS: Following training, a Diet x Training effect was observed (P = 0.015). The protein level of Bdnf in PNGR (1.24 ± 0.42 a.u.) was significantly lower compared to CON (1.64 ± 0.49 a.u., P < 0.05). Increased Bdnf protein level was observed in CON-TRD (2.01 ± 0.37 a.u) compared to CON-SED (1.25 ± 0.27 a.u, P < 0.05) but there was no significant difference was observed between PNGR-SED (1.24 ± 0.38 a.u.) and PNGR-TRD (1.24 ± 0.48, P = 0.974 a.u.). CONCLUSION: HIIT didn't increase the Bdnf protein expression in PNGR mice cerebrum, suggesting PNGR brain may not positively respond to exercise.