Nucleus raphe pallidus
Encyclopedia
The nucleus raphe pallidus receives afferent connections from the periaqueductal gray
, the Paraventricular nucleus of hypothalamus, central nucleus of the amygdala
, lateral hypothalamic area, and parvocellular reticular nucleus
.
Also, the pallidus receives afferents from the medial preoptic area, median preoptic nucleus and lateral paragigantocellular reticular nuclei .
The pallidus has recently been shown to be involved in the activation of a fever as an immunoreaction. It has been implied that the preoptic area is constantly inhibiting the raphe pallidus, especially the rostral portion, with GABA
.
When the preoptic area receives immune signals from the body, the inhibition stops and the rostral portion of the raphe pallidus excites the intermediolateral cell column, which induces a fever .
The raphe pallidus has also been known to mediate the tachycardia response, an extremely high heart rate known to be incited by emotional or psychological stress.
Microinjections of a GABA-a antagonist into the raphe pallidus, induces an increased heart rate.
Conversely, microinjections of muscimol, a GABA-a agonist
, inhibit tachycardia in rats under air-stress stimuli.
In both of these cases, GABA is mediating two different sympathetic responses, so clearly the nucleus raphe pallidus is a far more a complex nucleus than previously thought.
Periaqueductal gray
Periaqueductal gray is the gray matter located around the cerebral aqueduct within the tegmentum of the midbrain. It plays a role in the descending modulation of pain and in defensive behaviour...
, the Paraventricular nucleus of hypothalamus, central nucleus of the amygdala
Amygdala
The ' are almond-shaped groups of nuclei located deep within the medial temporal lobes of the brain in complex vertebrates, including humans. Shown in research to perform a primary role in the processing and memory of emotional reactions, the amygdalae are considered part of the limbic system.-...
, lateral hypothalamic area, and parvocellular reticular nucleus
Parvocellular reticular nucleus
The parvocellular reticular nucleus is part of the brain located dorsolateral to the nucleus reticularis pontis caudalis.The dorsal portion of the reticular nucleus has been shown to innervate the mesencephalic trigeminal nucleus and its surrounding area....
.
Also, the pallidus receives afferents from the medial preoptic area, median preoptic nucleus and lateral paragigantocellular reticular nuclei .
The pallidus has recently been shown to be involved in the activation of a fever as an immunoreaction. It has been implied that the preoptic area is constantly inhibiting the raphe pallidus, especially the rostral portion, with GABA
Gabâ
Gabâ or gabaa, for the people in many parts of the Philippines), is the concept of a non-human and non-divine, imminent retribution. A sort of negative karma, it is generally seen as an evil effect on a person because of their wrongdoings or transgressions...
.
When the preoptic area receives immune signals from the body, the inhibition stops and the rostral portion of the raphe pallidus excites the intermediolateral cell column, which induces a fever .
The raphe pallidus has also been known to mediate the tachycardia response, an extremely high heart rate known to be incited by emotional or psychological stress.
Microinjections of a GABA-a antagonist into the raphe pallidus, induces an increased heart rate.
Conversely, microinjections of muscimol, a GABA-a agonist
Agonist
An agonist is a chemical that binds to a receptor of a cell and triggers a response by that cell. Agonists often mimic the action of a naturally occurring substance...
, inhibit tachycardia in rats under air-stress stimuli.
In both of these cases, GABA is mediating two different sympathetic responses, so clearly the nucleus raphe pallidus is a far more a complex nucleus than previously thought.