Morphine is a class of drugs known as opioid (narcotic) analgesics. It can help to relieve moderate to severe pain, which by changing how your body feels and responds to pain. Morphine will activate mu-type opioid receptor, which the later will activate the G-proteins (guanine nucleotide-binding proteins). G proteins regulate metabolic enzymes, ion channels, transporter proteins. In this pathway, G proteins activate potassium voltage-gated channel (GIRK) as well as inhibit calcium voltage-gated channel and SNARE proteins. SNARE proteins mainly mediate the vesicle fusion. In this pathway, the synapse vesicles are required to be fused into cell membrane in order to release the neurotransmitter from brain cell. Inhibition of SNARE proteins deregulates the fusion of synapse vesicles which make neurotransmitter unable to be released as result. In order words, the pain signal (as in the neurotransmitters) won't be able to pass across the brain. Therefore, the pain is relieved in some extent.

Morphine Pathway Xuan Demo References