Synaptic function and psychopharmacology

The Synapse and Neurotransmitters

• Connection between neurons involves the action potential and neurotransmitter release.

• Calcium ions (Ca2+) are crucial for neurotransmitter release in synaptic transmission.

Communication in the Central Nervous System

• Each neuron receives thousands of synaptic inputs.

• Generates simple outputs (Action Potentials).

• Plays a role in neural computation.

Types of Neurotransmitters

• Variety of neurotransmitters exist, including:

  • Acetylcholine: First known neurotransmitter; excita tory, key in memory formation, At nerve-muscle connections of all voluntary & many involuntary muscles, low levels in Alzheimer's.

  • Noradrenalin: Involved in regulating processes like heart rate, BP and mood regulation; associated with arousal, alertness, and concentration, cocaine influences the activity of noradrenaline in the brain or body.

  • Dopamine: Critical for movement, attention, learning, affected in Parkinson's Disease.

  • Serotonin: Versatile functions including mood regulation; associated with various mental disorders.

  • GABA: Major inhibitory neurotransmitter; implicated in epilepsy, affected by substances like benzodiazepines.

Neurotransmitter Mechanisms

• Drug interactions can occur at various points in neurotransmitter function:

  • Synthesis, release, receptor interaction, reuptake, and inactivation.

• Agonists mimic neurotransmitters while antagonists block their effects.

Clinical Disorders - Parkinson’s Disease

• Symptoms include tremors, rigidity, poor balance, and cognitive effects.

• Treatment often involves L-Dopa, a precursor of dopamine; however, side effects may occur from peripheral conversion.

Treatment - Alzheimer’s Disease

• Characterized by ACh depletion and neuronal degeneration.

• Current treatments aim to inhibit degradation (AChE inhibitors) or enhance ACh release.

Pharmacological Treatments in Mental Health

• Includes neuroleptics, MAOIs, SSRIs, benzodiazepines, and beta-blockers.

• Some debates exist on their efficacy and the chemical imbalance theory.

Psychoactive Drugs: Uses & Abuses

• Categories of psychoactive drugs:

  • Sedatives: (e.g., benzodiazepines, alcohol)

  • Opiates: (e.g., morphine, heroin)

  • Stimulants: (e.g., amphetamines, cocaine)

  • Psychedelics: (e.g., LSD, psilocybin)

Cannabis: Effects and Uses

• Cannabis consists of THC and other cannabinoids, can induce bronchodilation, anti-emetic effects, and has applications in glaucoma treatment.

• Two primary types of cannabinoid receptors (CB1 and CB2) affect various physiological processes.

Addiction vs. Dependence

• Differences between addiction (compulsive behavior) and dependence (physiological adaptation).

• Tolerance development involves up-regulation or down-regulation of receptors affecting sensitivity.