INTRODUCTION

To facilitate the understanding of the pharmacological and unwanted effects of CNS drugs, the
physiological functions of the main CNS neurotransmitters are discussed briefly.
Noradrenaline. Noradrenergic transmission is important in control of mood (functional deficiency
resulting depression) controlling wakefulness, and alertness.
Dopamine. Dopamine is important in motor control (Parkinsonism is due to dopamine
deficiency), has behavioural effects (excessive dopamine activity is implicated in schizophrenia),
important in hormone release (prolactin, GH) and dopamine in chemoreceptor trigor zone
causes nausea and vomiting.
5-HT. Physiological functions associated with 5-HT pathways include; feeding behaviour,
behavioural response (hallucinatory behaviour), control of mood and emotion, control of body
temperature and vomiting.
Acetylcholine(Ach). Ach has effects on arousal, on learning, and on short-term memory.
Dementia and parkinsonism are associated with abnormalities in cholinergic pathways.
GABA. GABA is an inhibitory neurotransmitter in CNS.
Glycine. is an inhibitory neurotransmitter, acts on GABA like receptor in the spinal cord.