Scientists identify connection between dopamine and behavior related to pain and fear

[Indigophoton]

The work was done in mice. The method used to modulate dopamine levels - optogenetics - was new to me, and fascinating. The researchers think their work has relevance to depression and PTSD.

Should low dopamine levels prove to be relevant in ME, some of the results from the study may also suggest another possible reason why some people anecdotally find cannabinoids helpful.

Scientists at the University of Maryland School of Medicine have for the first time found direct causal links between the neurotransmitter dopamine and avoidance—behavior related to pain and fear.

Researchers have long known that dopamine plays a key role in driving behavior related to pleasurable goals, such as food, sex and social interaction. In general, increasing dopamine boosts the drive toward these stimuli. But dopamine's role in allowing organisms to avoid negative events has remained mysterious.

The new study establishes for the first time that dopamine is central in causing behavior related to the avoidance of specific threats. The work was published today in the journal Current Biology.

The researchers also examined the role that endocannabinoids play in this process. Endocannabinoids, brain chemicals that resemble the active ingredients in marijuana, play key roles in many brain processes. Here, Dr. Cheer and his colleagues found that endocannabinoids essentially open the gate that allows the dopamine neurons to fire. When the researchers reduced the level of endocannabinoids, the animals were much less likely to move to avoid shocks.

Dr. Cheer argues that the research sheds light on brain disorders such as post-traumatic stress disorder and depression. In depression, patients feel unable to avoid a sense of helplessness in the face of problems, and tend to ruminate rather than act to improve their situation. In PTSD, patients are unable to avoid an overwhelming sense of fear and anxiety in the face of seemingly low-stress situations. Both disorders, he says, may involve abnormally low levels of dopamine, and may be seen on some level as a failure of the avoidance system.

https://medicalxpress.com/news/2018-04-scientists-dopamine-behavior-pain.amp

 

[chrisb]

When l read Oliver Sacks description of the encephalitis lethargica cases I thought they bore significant resemblances, which were worth exploring. But good luck with trying to persuade a GP. Tests on mice may be permitted, but as for humans......

Edited for typos and to correct Oliver Sacks