d-Amphetamine: A CNS (central nervous system) psychomotor stimulant used for treating ADHD and narcolepsy (sleep disorder that causes abnormal sleepiness). As a performance-enhancer, it improves brain concentration, memory, and physical stamina and some behavioural emergencies as mania and toxic delirium.
Chlorpromazine: First-generation antipsychotic drugs that are therapeutically used for treating schizophrenia, anxiety, and bipolar disorder.
Diazepam: Belongs to benzodiazepines family and the medical reasons for use include anxiety, opiate and alcohol withdrawal symptoms, vertigo, and tetanus by reduction of muscle tone and coordination. It presents as an anxiolytic, antiepileptic and anticonvulsant drug.
Reserpine: It is therapeutically
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Morphine: Primarily used as a painkiller in acute and chronic pain, it is also used to treat myocardial infarction (heart attacks). It presents as an opioid or analgesic drug.
2. At what receptors or signalling systems are these ligands active? d-Amphetamine: Targets the TAAR1 receptor on various types of monoaminergic neurons, increasing neurotransmission in the CNS. The main target is different transporters such as MAO and NET and inhibits them in order to increase the levels of neurotransmitters such as Dopamine.
Chlorpromazine: Targets the dopamine receptors D1 to D5 in the CNS and inhibits amphetamine-induced behavioural changes. It has highest binding affinity to D2 receptor.
Diazepam: It is a positive allosteric modulator of GABA type A receptors in the CNS, particularly in the limbic system, thalamus, and hypothalamus.
Reserpine: It is an antagonist that irreversibly blocks the vesicular monoamine transporters (VMAT) on neurons in the CNS. It blocks the transport of Noradrenaline into the synaptic
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One example is blocking neuronal transporter (NET), thus blocking the uptake of amines by nerve terminals, by competition for the binding site of the amine transporter. This raises the level of neurotransmitter in the synaptic cleft, increasing CNS activity.
Morphine: In the nociceptive neurons pathway, opioid drug or also called opiates. Opioids are agonists that act on opioid receptors coupled to Gi/Go-protein-coupled receptors and exert powerful effects on ion channels on neuronal membranes.
Opioids helps opening of potassium channel to cause hyperpolarization of the cell and inhibit the opening of voltage-gated calcium channels. This decreases neuronal excitability and reduce transmitter release due to inhibition of Ca2+ influx.
Mostly morphine is distributed in the brain and spinal cord. Nociceptive neurons are specific for detecting pain. At the spinal level, Morphine inhibits transmission of nociceptive impulses and suppress nociceptive spinal reflexes. In more detail, morphine can promote the inhibitory pathways and release 5-HT and noradrenaline which can indirectly suppress the excitation of transmission neuron. Morphine can also inhibit directly the excitation of nociceptive transmission, thus the pain feeling is greatly