serotonin tagged posts

External stimulus causing excitement such as laughter by a joke augments the amygdala activity. In narcolepsy patient (left) lacking orexin neurons, activities of the amygdala become excessive, causing cataplexy. In healthy person (right), orexin neurons augment the activities of serotonin neurons in the dorsal raphe nucleus, which reduce activities of the amygdala due to increased release of serotonin in the amygdala, which in turn inhibits cataplexy. Credit: Kanazawa University

The brain is equipped with sleep mechanism and wakefulness mechanism, which are regulated to be on or off in an adequate manner. It is orexin*1 that is important in regulating this switch...

Image1: Serotonin transporter expression (marked in brown) in human colon. Image2: TLR2 mRNA and protein expression in 5-HT treated cells.

Scientists at the University of Exeter Medical School and University of Zaragoza in Spain studied a protein TLR2, a critical detector of the microbiota found in the intestine. They found that it regulates levels of serotonin – a neurotransmitter of the brain and also found in the gut, where it regulates our bowel routines. The research in cell cultures and verified in mice, provides strong evidence that microbiota can interfere with human physiology by modulating the serotonin transporter activity...

Serotonergic neurons in the dorsal raphe nucleus (DRN) and median raphe nucleus (MRN) of the brainstem differentially modulate emotional behavior. Credit: Columbia University Department of Psychiatry

More nuanced view of brainstem neurons could lead to better drugs for depression, anxiety. Low levels of serotonin in the brain are known to play a role in depression and anxiety, and it is customary to treat these disorders with medications that increase the amount of this neurotransmitter. However, a new study suggests that this approach may be too simple. It appears that neighboring serotonin-producing brainstem regions exert different and sometimes opposing effects on behavior.

“Our study breaks with the simplistic view that ‘more is good and less is bad,’ when it comes to serotonin for mo...