Posted by SLS on March 30, 2008, at 9:51:48
Histamine is a major monoamine neurotransmitter in the brain that serves quite often to promote psychic energy. There are three types of histamine receptors (H1 - H3). H1 receptors act to decrease appetite. Histamine inhibits noradrenaline release from hypothalamic nerve terminals in the PVN (paraventricular nucleus), and thus suppresses feeding behavior. These receptors might also increase metabolism as they seem to be the target of the weight-reducing hormone, leptin. H2 receptors are associated with brain structures in the amygdala, basal ganglia and hippocampus, and are associated with arousal. H3 are autoreceptors that help to control neurotransmission through histamine release inhibition. Overall, brain histamine contributes to a higher level of alertness and arousal, and facilitates changes in libido, learning, and memory. It should be noted that histamine does not cross the blood brain barrier. All of the brain's histamine must be synthesized there. A mast cell reaction will involve only peripheral tissues.
There are now a few researchers looking at the role that brain histamine dynamics plays in mental illness. It has been demonstrated that people with depression have a lower concentration of histamine H1 receptors than normals, and that the degree of reduction is associated with the severity of depression.
- Scott
poster:SLS
thread:820652
URL: http://www.dr-bob.org/babble/neuro/20080204/msgs/820652.html