I talked in the past of the importance of the dopamine receptor 2, D2, for a number of important behaviors (low D2 receptor levels is associated with pathological gambling (Comings et al., 1996), addiction (for review see: Foll et al., 2009), and obesity (Stice et al., 2008).
And I recently discussed the importance of D2 for learning from your mistakes. At the end of that blog piece I promised that I would tell, my small number of readers, in a future post how to increase your D2 levels, so I figured it was time to follow up (thanks Tom and Troy for the reminder).
1) Become the head (leader) of the pack.
There was a very interesting study done on primates (Morgan et. al., 2002, Nature Neuroscience) which tells us an interesting story about how your place in society can affect the molecular biology of your brain. More specifically in this case how your ranking in the social hierarchy can change your D2 levels.
From my pieces on the neuroscience of hope:
In a landmark primate study (Morgan et al., 2002, Nature Neuroscience) singly housed monkey brains were scanned for D2 binding capacity (n = 20). Next the primates were allowed out of their individual cages for the first time so all the animals were now together, and as you can guess a social hierarchy was formed. After a stable hierarchy was formed they re-scanned the primates brains. The high ranking animals D2 binding capacity increased by approximately 20% (the authors believe based on rat studies that singly housed animals have a lower than normal D2 levels at baseline, and therefore suggests that falling lower in the social hierarchy would cause a reduction in D2 levels if the animals start at a ‘normal’ baseline), however D2 levels in the low ranking individuals did not change.
(side note: there is always a problem with these studies because it is both the amount of ‘released’ dopamine and the number of D2 receptors that can affect this binding assay. If there is a high level of dopamine then there is not many available D2 receptors to bind the tagged D2 binder which the measured outcome, but there can be low binding because of simply low D2 levels.)
As a functional test of the D2 levels cocaine was offered to all the primates, Consistent with a large body of literature the primates with the lowest D2 levels had the largest intake of cocaine. The high ranking primates with their high D2 levels were the lowest users of cocaine (again consistent with the literature). The functional cocaine test lends support to the author’s conclusion that the high ranking animals did have higher D2 levels (and not just lower dopamine levels).
Take home: become the leader of any, or multiple, social hierarchies. This could be in your office, your Tuesday night poker game, your book club, your warcraft group, etc, etc. I think you get the picture. If you are at the top of the pack you will get an increase of the D2 (and less likely to get addicted to drugs - all other things being equal).
Foley and Fleshner 2008, study in rodents found that 6 weeks of exercise (wheel running) increased D2 levels in the caudate putamen (part of the striatum). I haven’t come across a human study that has examined D2 levels after X number of weeks of exercise - though I am surprised somebody hasn’t done it.
From the paper:
Taken together, these results suggest that (1) the increased
levels of mRNA for D2 receptors likely result in an
increase in D2 expression, and (2) alterations in D2
receptor expression may be involved in the mechanisms by
which habitually physically active animals are better able
to delay fatigue compared to sedentary controls.
Therefore, not only does regular exercise decrease fatigue, as you would expect (adaptation), but the increase of D2 would likely lead to better learning from your mistakes, not to mention maybe protect your from addiction, gambling, and obesity (at more than one level).
Take home: Exercise to increase your D2 levels - and all the other good things it does - you have everything to gain.
3) Become the top dog in something athletic.
You can see the obvious interaction of 1 and 2. The act of exercise will increase your D2 levels, and with enough training/practice you might be able to become the leader of your sport or team (this could be at the neighborhood level, the city level, etc). I guess the trick is to pick the appropriate level where you can be the top dog. I am not saying this will help your overall chosen sport ability, for to really improve in a sport you need to keep challenging yourself by competing against people who are better than you.
So you see the dichotomy here, what is good for your overall athletic ability might not be good for your overall D2 levels. You have to choose what is most important to you
A start to increasing your D2 levels:
Well I gave you two of the most prominent ways to increase your D2 levels (and the combo). There are other things that will result in changes in your D2 levels - either up or down, and I will try to discuss some of these in a later post. But for now try to become a leader of something, and get out there and exercise.
To better learning from your mistakes - and much more.
(in reality there is far more to this story, with many nuiances, but I can’t begin to fit the complexity of this field of research in these short blog pieces)