Madan BaralB. Pharmacy 3rd Semester

Roll-8

• Identify neurotransmitters• Understand the physiology of neurotransmission• Classify neurotransmitters• Biosynthesis• Major neurotransmitter systems : simple anatomy

and functions

• Neurotransmitters are endogenous chemicals which transmit signals from a neuron to a target cell across a synapse.

• Ramón y Cajal (1852–1934) discovered a 20 to 40 nm gap between neurons, known today as the synaptic cleft.

• In 1921, German pharmacologist Otto Loewi (1873–1961) confirmed that neurons can communicate by releasing chemicals.

• Otto Loewi is accredited with discovering acetylcholine (Ach)-the first known neurotransmitter

• However, some neurons communicate via electrical synapses

How do we identify if a compound is a neurotransmitter?

Chemical can be classified as a neurotransmitter if it meets the following conditions:1.There are precursors or synthesis enzymes located in the presynaptic side of the synapse2.It is available in sufficient quantity in the presynaptic neuron to affect the postsynaptic neuron.3.There are postsynaptic receptors and the chemical is able to bind to them.4.A biochemical mechanism for inactivation is present.

1. Small Molecule transmitters Mono Amines

• Acetylcholine• Serotonin• Histamine

Catecholamines• Dopamine• Norepinephrine• Epinephrine

Amino acids• Glutamate• Gamma-amino butyric acid (GABA)• Glycine

2. Large Molecule TransmittersNeuropeptides

•Substance P and Other Tachykinins•Opoid Peptides

3. Other Chemical Transmitters• Cannabinoids• Gases (NO)

Neurotransmitter Source Site of Synthesis

Acetylcholine Choline CNS, parasympathetic nerves

Serotonin Tryptophan CNS, chromaffin cells of the gut, enteric cells

GABA Glutamate CNS

Histamine Histidine hypothalamus

Epinephrine Tyrosine adrenal medulla, some CNS cells

Norepinephrine Tyrosine CNS, sympathetic nerves

Dopamine Tyrosine CNS

Nitric oxide Arginine CNS, gastrointestinal tract

C.CATECHOLAIMNES

• Cholinergic • Dopaminergic• Noradrenergic• Serotonergic

Functions• In PNS

– Induces skeletal muscle contraction

• In CNS– Arousal and reward– Enhancement of

sensory perceptions when we wake and in sustaining attention

Functions• Behavior and cognition• Voluntary movement• Motivation, punishment

and reward• Mood, attention, working

memory, and learning

Functions• Affects amygdala, where

attention and responses are controlled

• Increasing heart rate, triggering the release of glucose from energy stores

• Increasing blood flow to skeletal muscle

• Increases the brain's oxygen supply

Functions• Mood• Cognition• Sleep• Memory Processing

• Schizophrenia• Parkinson’s Disease• Alzheimer’s Disease• Dementia• Bipolar Disorder• Depression• Sleep Disorder

• Neurotransmitters are the wonder chemicals of human body.

• URL1-http://en.wikipedia.org/Neurotransmitters• Barren et al. (2005), Ganong’s Review of Medical Physiology (23rd

Ed.), Elsevier, pp 223-297