Physical exercise increases adult hippocampal neurogenesis in male rats provided it is aerobic and sustained

Key points summary
 Aerobic exercise such as running enhances adult hippocampal neurogenesis (AHN) in rodents.
 Little is known about the effects of high-intensity interval training (HIT) or of purely anaerobic
resistance training on AHN.
 Here, compared to a sedentary lifestyle, we report a very modest effect of HIT and no effect of
resistance training on AHN in adult male rats.
 We find most AHN in rats that were selectively bred for an innately high response to aerobic
exercise that also run voluntarily and - increase maximum running capacity.
 Our results confirm that sustained aerobic exercise is key in improving AHN. 

Aerobic exercise, such as running, has positive effects on brain structure and function, for example,
adult hippocampal neurogenesis (AHN) and learning. Whether high-intensity interval training (HIT),
referring to alternating short bouts of very intense anaerobic exercise with recovery periods, or
anaerobic resistance training (RT) has similar effects on AHN is unclear. In addition, individual
genetic variation in the overall response to physical exercise likely plays a part in the effects of
exercise on AHN but is less studied. Recently, we developed polygenic rat models that gain
differentially for running capacity in response to aerobic treadmill training. Here we subjected these
Low Response Trainer (LRT) and High Response Trainer (HRT) adult male rats to various forms of
physical exercise for 6 to 8 weeks and examined its effects on AHN. Compared to sedentary animals,
the highest number of doublecortin-positive hippocampal cells was observed in HRT rats that ran
voluntarily on a running wheel while HIT on the treadmill had a smaller, statistically non-significant
effect on AHN. AHN was elevated in both LRT and HRT rats that endurance trained on a treadmill
compared to those that performed RT by climbing a vertical ladder with weights, despite their
significant gain in strength. Furthermore, RT had no effect on proliferation (Ki67), maturation
(doublecortin) or survival (BrdU) of new adult-born hippocampal neurons in adult male Sprague-
Dawley rats. Our results suggest physical exercise promotes AHN most if it is aerobic and sustained,
and especially when accompanied by a heightened genetic predisposition for response to physical
Keywords: aerobic exercise, resistance training, high-intensity interval training, doublecortin
immunohistochemistry, dentate gyrus 

Autor / Fonte:Miriam S. Nokia, Sanna Lensu, Juha P. Ahtiainen, Petra P. Johansson, Lauren G. Koch, Steven L. Britton & Heikki Kainulainen