Drugs

Excitatory drugs:

-NICOTINE
Found in tobacco products. It is a stimulant which mimics the neurotransmitters acetlcholine (Ach) as they bind to the same receptors. It causes the calming effect. Unlike Ach the nicotine cannot be broken down by the enzme acetyl choline esterase. Therefore the effect of nicotine is longer lasting. The effect is pleasure because the nicotine excites the post synaptic neurone releasing a molecule called dopamine. And dopamine gives the feeling of pleasure the molecules is a 'reward' of our brains.

-COCAINE
Dopamine transporters are responsible for removing dopamine molecules from the synaptic cleft after they have done their job.
However, cocaine blocks and inhibits the activities of these transporters. Thus dopamine is trapped in the synaptic cleft. Therefore dopamine binds again and again to the receptors resulting in the overstimulation of the cell.

Outcome: concentrates the reward pathway of our brain. The part that also controls voluntary movements. This is why concaine users are unable to stay still.

-AMPHETAMINE
-stimulates tramission of adrenergic synapses and gives the user energy and increase alertness.
This drug moves into the cesciles of the presynaptic neurgone and cuases their release into the synaptic cleft. Normally these neurotransmitters would be broken down by enzymes but the amphetamine inhibits this from happening.

The high concentrations of dopamine cause euphoria as high concentraions of noradrenaline cause increased alertness and energy.

Inhibitory drugs

-BENZODIAZEPINE
medical use: reduces anxiety and against epileptic seizuers.

Benzodiapine increases the binding of GABA which is an inhibitory neurotransmitters. When the GABA binds to the post synaptic membrane it causes chloride ions to enter and potassium ions to exit . This hypoerpolarizes the neurone and inhibits an action potential from being generated.

The increased binding of GABA causing the post synaptic neurone to become more hyperpolarized.


-ALCOHOL

When alcohol enters the brain it interacts with GABA receptors to make them more inhibitory and it beinds to glutamate receptrs repventing the glutamate from exciting the cell.

As a result the areas invovling memory formation, decision-making and impulse control is slowed down.

-TETRAHYDROCANNABINOL [THC]

This is the main chemical in marijuana.
Usually inhibitory neurotransmitters are active in the synapse. These neurotransmitters inhibits dopamine from being released.

The active chemical in marijuana binds to the receptors that inhibit the release of dopamine: cannabinoid receptors. As a result the inhibition if turned off and dopamine is allowed to squirt into the synapse.
As a result the user feels increased pleasure due to the abnormally high concentrations of dopamine.