Neurotransmitter involved in pain
Excitatory:
Inhibitory:
· GABA - mediates gate control in dorsal horn by synapsing on neurons that contain substance P.
- GABAA Rs- ligand gated ion channel (ionotropic), fast inhibition
- GABAB Rs- activates G proteins (metabotropic), slow inhibition
Descending Pain Regulation:
· Norepinephrine
· Serotonin
High concentrations of 5-HT and NA containing terminals are found in the spinal cord, especially in the superficial dorsal/posterior horns, where the terminals of small diameter primary afferent fibres make synaptic contact with second-order neurons of the spinal cord. 5-HT and NA in this area of the spinal cord are critically important for modulating pain sensitivity through their presence in the descending pain pathways (Figure 1).[20] Persistent pain arises from changes in sensitivity within ascending and descending pain pathways in the brain and spinal cord.[21] Under normal circumstances, descending serotonergic and noradrenergic pathways suppress routine ascending input from the periphery (headache, musculoskeletal pain and abdominal pain) to the brain in such a way that attention can be paid to events occurring outside the body. Dysfunction of the descending inhibitory pathway allows routine inputs to ascend via the spinal cord to the brain where they are interpreted as pain, which explains the painful physical symptoms associated with depression.[22] Although other neurotransmitters are involved, both 5-HT and NA have been implicated as mediators of endogenous analgesic mechanisms in descending pain pathways. The precise mechanism involved in pathogenesis of persistent pain is not fully understood, but a growing body of evidence indicates that disinhibition and imbalance of 5-HT and NA could contribute to persistent pain mechanisms.[
· opiates - relieve pain by stimulating mu and delta receptors
Pain gates can also be shut by activating neurons that release endorphins in the PAG
-Periaqueductal gray area (PAG) which presumably mediate the actions of endorphins and enkephalins.
I never go to my doctor anymore asking for pain killers prescription and then be turned down at the end, all I do is order online from www.medsheaven.com hassle free and low cost, they have three pain killers listed on their website which are ultram tramadol celebrex that you buy, and the best part is no prescription required!!!
ReplyDelete