W3L2: Peptides, Lipids, Nucleosides, Gases

peptides: structure

building blocks of proteins consist of two or more amino acids (either produced naturally in body or consumed through food)

peptides: synthesis

not synthesised from smaller compounds but product of larger compounds (poly-peptides) being broken down into peptides within neuron before release at terminal button

peptides: modulation

serve as modulators but can also act as neurotransmitters and co-release with neurotransmitters (same compound having multiple roles and functions in different contexts)

peptides: opiates

high density of opioid receptors in brain in areas involved in pin

peptides: endogenous opiods

originating internally - opium

peptides: opiates

drugs (morphine, heroin, opium)

peptides: opiates: heroin

full agonist (not neurotoxic but can cause death/respiratory failure)

peptides: opiates: buprenorphine

partial agonist at receptors used as treatment for heroin dependence

peptides: opiates: naloxone

full antagonist and can be used to rapidly block effect of heroin and prevent overdose (no stimulating effect - blocks receptor so person is brought out of overdose) very painful as it blocks all opioid receptors

peptides: opiates: methadone

agonist and is used in treatment of dependence because it has much slower course than heroin

lipids

naturally occurring molecules that include fats, waxes and others (hydrophobic - water fearing) - main biological function is energy storage, signalling and providing structural components of cell membranes

lipids: synthesis

synthesis pathways remain unclear but many serve as neurotransmitters/modulators

lipids: endocannabinoids

best known lipid neurotransmitters (two receptors CB1 and CB2)

lipids: endocannabinoids: CB1

found in brain - responsible for main psychological effects - receptor activation, shortens duration of action potentials in presynaptic neuron decreasing amount of neurotransmitter released

lipids: endocannabinoids: CB2

found in peripheral tissue

lipids: endocannabinoids: role

shortening duration of action potentials in presynaptic neuron and decreasing amount of release - dampening down and modulating neurons

lipids: CB1: locations

basal ganglia, cerebellum, cerebral cortex, hypothalamus, medulla, hippocampus, spinal cord

lipids: cannabis

THC = active ingredient, acts on CB1 receptors

lipids: cannabis: hippocampus

shortens duration of action potentials, dampening down on hippocampus neuronal qualities (has memory effects)

lipids: CB1 locations: cerebellum

movement

lipids: CB1 locations: basal ganglia

movement

lipids: CB1 locations: cerebral cortex

higher cognitive function

lipids: CB1 locations: hypothalamus

appetite

lipids: CB1 locations: hippocampus

learning, memory, stress

lipids: CB1 locations: medulla

nausea/vomiting, chemoreceptor trigger zone

lipids: CB1 locations: spinal cord

peripheral sensation including pain

nucleosides

subunit of nucleic acids, heredity-controlling components of all living cells (DNA and RNA) - obtained by chemical/enzymatic breakdown of nucleic acids (modulate release of other transmitters)

nucleosides: adenosine

forms breakdown of adenosine triphosphate (ATP)

nucleosides: adenosine triphosphate (ATP)

primary energy source in cells for transport systems and many enzymes

nucleosides: adenosine: levels

when you are awake levels gradually rise and in normal conditions promotes sleep and suppresses arousal

nucleosides: adenosine: at synapse

where adenosine is primary neurotransmitter, high postsynaptic firing rate leads to sleepiness (increased firing = reduced activation/arousal)

nucleosides: caffeine

acts as adenosine-receptor antagonist and blocks bodies natural action of adenosine

nucleosides: caffeine: plants

acts as natural pesticide that paralyses and kills insects that attempt to feed on the plants

nucleosides: caffeine: increase altertness

because adenosine increases firing rate in brain areas that promote sleepiness, caffeine increases alterness by reducing firing/activation of these neurons

gases: gases in neurotransmitters

nitric oxide and carbon monoxide

gases: nitric oxide (NO)

main role in dilating blood vessels - produced from amino acid Arginine in subpopulation of 1-2% of neurons in cortex

gases: nitric oxide: function

involved n learning and memory through effects on synaptic plasticity, dilates blood vessels in regions of brain that become metabolically active (rush of blood in all areas of brain)

gases: nitric oxide: difference from traditional neurotransmitters

not synthesised and stored in vesicles, produced throughout cell including dendrites and defuses out of cell as soon as produced, doesn’t activate receptors but simply enters neighbouring cell, short lived and degraded or acted within few seconds of being produced