Question

The endocannabinoid system revealed a new mechanism for modulating activity at synapses. What is it called and how does it work?

Psychopharmacology class

Answer 1

ENDOCANNABINOID SYSTEM:

The endocannabinoid system ( ECS) is composed of endocannabinoids, which are lipid-based neurotransmitters that bind to cnnabinoid receptors, and cannabinoid receptors protein that are expressed throughout the central nervous system including brain and pheripheral nervous system.

SYNAPSE:

the word synapse is derived from Greek. It is a junction or communication between two nerve cells (neurons), witha minute gap , throught which impulses pass (electrical or chemical signals) by diffusion of a neurotransmitter. it is basically like a switch between two brain cells.

The endocannabinoid system revealed a new mechanism for modulating activity at synapses: Retrograde signaling

the new mechanism for activity at synapses in the mammalian brain:

since, tetrahydrocannabinol (THC) is the main psychoactive ingredient in identification of endogenous ligands- endocannabinoids. endocannabinoids is a powerful regulator of synaptic function throughout central nervous system. apart from producing synapses, the endocannabinoid system has been implicated in synapse formation and neurogenesis,by modulating the synapse strenght, the endocannabinoid can regulate neural functions, cognition,motor control. behaviour and pain.also dysregulation of endocannabinoid system, results in conditions like depression, stress and anxiety disorders. the other regulations by endocannaboid system are:

• gastrointestinal activity
• pain perception
• modulation of neurotransmitter release
• maintenance of bone mass
• protecting neurons
• hormonal balance
• immune functions
• metabolism

retrograde signalling with activity - dependent synaptic plasticity causes long term and short term depression. the level of release of neurotrophins by postsynaptic cells determines the activity on presynaptic neurons. they may induce in modifications of neurons excitability and synaptic transmission in the central nervous system directly.when the membrane is depolarized, the post synaptic releses endocannabinoid, a repetative synaptic activity can induce a persistant increase or decrease of synaptic efficacy resulting in either long term depression or long term potentiation .synaptic supression mediated by endocannabinoid provides a means for postsynaptic neurons to tune the sensitivity of their synaptic inputs to different patterns of stimulations. the endogenous cannabinnoids released by depolarized neuron can mediate in down regulation of GABAergic transmission in short term plasticity. in many parts of nervous system long term or short term depression depends on postsynaptic cell activation.blocking of excocystosis or endocytosis in the postsynaptic cell prevents long term potentiation or long term depression.