Dr David McGrath

Spine Physician

MB BS (Hons) FAFOM, RACP, FAFMM
Master of Pain Medicine

Neurotransmitters (NT's)
(stub article)

1. These are special messengers between neurons. They are released into the synaptic space, (under the influence of an action potential) where they diffuse along a concentration gradient to the receiving membrane. Receptors are activated by the chemical, changing the properties of sodium/potassium channels. As Na/K ions are exchanged, the membrane depolarizes. If a threshold is reached, an action potential is initiated,down the receiving nerve axon. The neurotransmitter chemical is either degraded or reabsorbed into the pre-synaptic membrane,or diffused into circulation.
2. There are many NT's creating functional connections between neurons.
3. Many NT have a specialised re-uptake receptor (protein) or transporter, in order to recycle the NT and to end the disurbance. eg Serotonin SERT, Nor-adrenaline(nor-epinephrine) NET
4. The actions and behaviour of membrane receptors, are influence by membrame composition,such as cholesterol content. eg SERT efficiency lower with low cholesterol.
5. Neuromodulators can be seen as neurotransmitters, that have poor pre-synaptic re-uptake or metabolism. As such, their concentrations can vary with brain activity,having a general modulating influence on more specific interactions. They tend to accumulate in spaces such as, intracellular space,CSF space,lymphatic space and general circulation. NT which tend to fall into this class are noradrenaline,Ach,DA,Serotonin. Because of their wider influence,they have hormone like properties.

	Action +/-	Molecule Class	Brain Domain	Functionality
Glutamate (GLU)	+	Peptide	Widespread	Multiple Excitatory
GABA	-	Peptide	Widespread	Multiple Inhibitory
Acetylcholine (Ach)	+/-	No generic Class	Ponto/mes/encephalo/ tegmental complex Sympathetic Para/sympathetic	Learning STM Arousal Reward ACE's
Dopamine (DA)	+	Monoamine	Meso/cortical Meso/limbic Nigro/striatal Tuber/infundibular	Motor System Reward System Cognition Endocrine Nausea
Serotonin 5-Ht		Monoamine	Caudal/dorsal Rostral/dorsal Raphe Nucleus Entero/chromaffin GIT	Introversion Mood Satiety Temperature Sleep Pain Inhibition Flushing/GIT/Nausea
Nor/Epinephrine (NE)		Monoamine	Locus Coeruleus Lateral Tegmental Field Sympathetic	Arousal Reward
Epinephrine (Epi) (Adrenaline)		Monoamine
Glycine (Gly)	+	Peptide		Spinal Reflexes Motor
Histamine (H)		Amine		Circadian Cycle Inflammatory
Melatonin		Mono/amine
Aspartate		Peptide
Dynorphin	-	Opioids	Spinal Cord	Sensory Modulation
Endorphin	-	Opioids	Spinal Cord	Sensory Modulation
Enkephaline	-	Opioids	Spinal Cord	Sensory Modulation
Substance P		Peptide	Brain/Spinal Cord	Neuromodulation
Nitric Oxide (NO)		Gas
Carbon Monoxide (CO)		Gas
Zinc		Metal
Anand/amide (AEA)		Cannabinoid
Taurine		Mono/amine		Inhibitory (Cf GABA)
N-acetyl/aspartyl/ glutamate (NAAG)	-	Peptide
Tyramine		Mono/amine
Hormones		Various	Widespread	Multiple

NT/Clinical	Receptors	Drugs	Therapeutics
Glutamate (GLU)	NMDA	Memantine (NMDA antagonist)	Demetia
GABA
Acetylcholine (Ach)	Nicotinic Muscarinic Ach Esterases	Nicotine (Smoking) Varenicline (Champix) Esterase Inhibitors	Smoking Demetia
Dopamine (DA)	D1 D2	Olanzapine Metoclopramide (maxolon)	Tardive Dyskinesia with D2 antagonism Antagonist action for nausea and pain
Serotonin 5-Ht	5HT-2	SSRI's Venlafaxine (Efexor) Receptor antagonist Olanzapine (zyprexa) Surgery for Carcinoid	Anti-depressants mood stabilizer Anti-psychotic Carcinoid Syndrome
Nor/Epinephrine (NE)	Alpha Beta	SNRI's Reboxetine (Edronax)	Anti-depressants
Epinephrine (Epi) (Adrenaline)	Alpha Beta
Glycine (Gly)
Histamine (H)	H1 H2	Cimetidine	Anti-ulcer
Melatonin	Mono/amine
Aspartate
Dynorphin	Mu Kappa Delta
Endorphin
Enkephaline
Nitric Oxide (NO)
Carbon Monoxide (CO)
Zinc
Anand/amide (AEA)	Cannabinoid Receptors
Taurine
N-acetyl/aspartyl/ glutamate (NAAG)
Tyramine
Hormones

1. Major Depressive Disorder- Serotonin and Noradrenaline potentiation (re-uptake inhibitors)
2. Generalised anxiety Disorder (GAD)- Serotonin potentiation
3. Social anxiety Disorder (SAD/social phobia)-Serotonin potentiation (lexapro)
4. Demetia- Acetylcholine potentiation
5. Demetia-Glutamate inhibition (NMDA antagonist)
(to be continued)