With Christmas come and gone for another year along with blunted Leptin and neurogenesis . It’s time to throw some coal into your hypothalamus and plant some new nerve cells into your hippocampus.
Now, I’m going to let you in on a not so secret on neurotrophins. Especially a neurotrophin that is getting a lot of attention in neuroscience.Before I dive straight in, neurotrophins are proteins that have a specificity in promoting growth and survival of mature nerve cells. BDNF (brain derived neurotrophic factor) is a subclass of neurotrophins that is responsible for the survival of neurons in the central nervous system. Along with synaptic plasticity and cognitive performance. As with normal healthy ageing. The hippocampus looses 1-2% of volume from the age of 55. Finding non pharmacological ways in increasing expression of BDNF is incredibly important for healthy ageing, and reducing the risk of developing a neurodegenerative disease. It is also hypothesised that BDNF is responsible for the uptake of serotonin in certain classes of anti depressants (SSRI). Hence why aerobic exercise can have an anti depressant effect. As refined sugar, a high fat diet, and physical inactivity all inhibit hippocampal neurogenesis, which sounds like Christmas day to me….
Lets now dive in!
BDNF is concentrated in the hippocampus; and is expressed in two isoforms. I will elaborate on one of the isoforms mature BDNF (mBDNF) which is important for many neuronal survival mechanisms.Physical activity, especially environmentally enriched aerobic exercise. Has been shown to increase serum levels of BDNF, which thus has the ability to cross the blood brain barrier (enter your brain and do cool stuff). Witch finally, as photosynthesis does for mother nature….GROWTH can occur!
Aerobic exercise, with the cardiovascular system being physiologically stressed in the right manner boosts serum levels of BDNF. When BDNF binds to it’s high affinity receptor TrkB (Tropomyosin receptor kinase B). A cascade of long term potentiating, neuronal survival & lastly all the way down to transcription of BDNF mRNA occurs. TrkB can only be influenced by mature BDNF. Which doesn’t leave to many avenues (exercise/intermittent fasting) to promote long term potentiating (increase in synaptic strength). As exercise has shown to up regulate thousands of genes. It’s mind boggling what a simple thing exercise can do. But when one thinks about it. Our ancestors needed their aerobic system to hunt, gather & runaway from threats. It is also no coincidence that intermittent fasting increases levels of BDNF. Reverting back to our ancestors. Food was not readily available at your nearest Coles. And thus for the brain to maintain adequate glucose homoeostasis. Hunger (fasting) resulted in neuronal survival; along with increased levels of norepinephrine for alertness and decision making.
Aim for 30 minutes (70-85% intensity) aerobic exercise. Keeping with the Australian physical activity guidelines (which is modest to say the least). Preferably outdoors; although one must confess to hitting the cross trainer/treadmill on a regular basis. Lastly be mindful of any musculoskeletal/cardiovascular issues!
Embracing the therapeutic benefits of aerobic exercise will hopefully motivate you to chuck on the runners. And take care of your 3 pounds of white/grey matter, and 100 billion neurons!