Enteric Nervous System (ENS)
The "second brain" — a network of 500 million neurons lining the GI tract that regulates digestion independently of the CNS. Richly innervated by the endocannabinoid system.
In Depth
The ENS contains as many neurons as the spinal cord and can function independently of the brain. CB1 receptors are densely expressed on enteric neurons, regulating intestinal motility, secretion, and pain signaling. Endocannabinoid tone in the gut is critical for normal GI function — ECS dysregulation is implicated in IBS, IBD, and functional GI disorders. THC's effects on appetite and nausea involve ENS CB1 receptor activation. The gut-brain axis, mediated partly by the ECS, connects GI function to mood, cognition, and stress responses.
Further Reading
More in Neuroscience
Retrograde Signaling
A form of synaptic communication where the postsynaptic neuron sends chemical signals back to the presynaptic neuron to modulate neurotransmitter release.
Neurogenesis
The process by which new neurons are formed in the brain. In adults, primarily occurs in the hippocampus (dentate gyrus) and olfactory bulb.
Neuroprotection
The preservation of neuronal structure and function against injury, degeneration, or disease.
Neuroinflammation
Inflammation of nervous tissue, involving activation of microglia and astrocytes and release of pro-inflammatory cytokines within the CNS.
Hippocampus
A brain region critical for memory formation, spatial navigation, and stress regulation. Highly enriched in CB1 receptors and particularly sensitive to cannabinoid effects.