Chapter 12 - Nervous Tissue - Study Guide - Testing Your Comprehension - Page 473: 1

The use of drugs like chlorpromazine in the treatment of schizophrenia is aimed at reducing the symptoms of the disorder by modulating neurotransmitter activity in the brain. Chlorpromazine is part of a class of drugs known as typical antipsychotics, which primarily target dopamine receptors. While these drugs can be effective in managing symptoms of schizophrenia, they can also lead to side effects that resemble those seen in Parkinson's disease. Here's an explanation of why this occurs: 1. **Dopamine and Schizophrenia**: - Schizophrenia is thought to involve an overactivity of dopamine signaling in certain brain regions. Excessive dopamine transmission is believed to contribute to the positive symptoms of schizophrenia, such as hallucinations and delusions. - Antipsychotic drugs like chlorpromazine work by blocking dopamine receptors, primarily the D2 subtype, to reduce the hyperactivity of dopamine in the brain. This helps alleviate the positive symptoms of schizophrenia. 2. **Dopamine and Motor Control**: - Dopamine is a neurotransmitter that plays a crucial role in motor control and coordination. In particular, it is involved in the regulation of fine motor movements. - Parkinson's disease is characterized by the degeneration of dopamine-producing neurons in a region of the brain called the substantia nigra. This leads to a significant reduction in dopamine levels in the brain, resulting in motor symptoms such as muscle tremors, rigidity, and impaired voluntary movements. 3. **Side Effect Mechanism**: - Antipsychotic drugs like chlorpromazine can inhibit dopamine receptors not only in the areas related to schizophrenia symptoms but also in the broader brain regions responsible for motor control. - By blocking dopamine receptors throughout the brain, these drugs can lead to a reduction in dopamine signaling in the motor control pathways, similar to what occurs in Parkinson's disease. - This reduction in dopamine activity can result in side effects like muscle tremors, rigidity, akinesia (difficulty initiating voluntary movements), and speech impairment, which resemble the motor symptoms seen in Parkinson's disease. 4. **Extrapyramidal Symptoms (EPS)**: - The motor side effects associated with antipsychotic drugs like chlorpromazine are collectively known as extrapyramidal symptoms (EPS). These symptoms can range from mild to severe and significantly impact a patient's quality of life. To mitigate these side effects, newer antipsychotic medications, called atypical antipsychotics, have been developed. These drugs target a broader range of neurotransmitter receptors and have a lower propensity to cause EPS compared to typical antipsychotics like chlorpromazine. However, the choice of antipsychotic medication is made by a healthcare provider based on the specific needs and response of the individual patient. Additionally, medical interventions or adjustments in medication can help manage EPS when they occur in patients taking typical antipsychotics.

The use of drugs like chlorpromazine in the treatment of schizophrenia is aimed at reducing the symptoms of the disorder by modulating neurotransmitter activity in the brain. Chlorpromazine is part of a class of drugs known as typical antipsychotics, which primarily target dopamine receptors. While these drugs can be effective in managing symptoms of schizophrenia, they can also lead to side effects that resemble those seen in Parkinson's disease. Here's an explanation of why this occurs: 1. **Dopamine and Schizophrenia**: - Schizophrenia is thought to involve an overactivity of dopamine signaling in certain brain regions. Excessive dopamine transmission is believed to contribute to the positive symptoms of schizophrenia, such as hallucinations and delusions. - Antipsychotic drugs like chlorpromazine work by blocking dopamine receptors, primarily the D2 subtype, to reduce the hyperactivity of dopamine in the brain. This helps alleviate the positive symptoms of schizophrenia. 2. **Dopamine and Motor Control**: - Dopamine is a neurotransmitter that plays a crucial role in motor control and coordination. In particular, it is involved in the regulation of fine motor movements. - Parkinson's disease is characterized by the degeneration of dopamine-producing neurons in a region of the brain called the substantia nigra. This leads to a significant reduction in dopamine levels in the brain, resulting in motor symptoms such as muscle tremors, rigidity, and impaired voluntary movements. 3. **Side Effect Mechanism**: - Antipsychotic drugs like chlorpromazine can inhibit dopamine receptors not only in the areas related to schizophrenia symptoms but also in the broader brain regions responsible for motor control. - By blocking dopamine receptors throughout the brain, these drugs can lead to a reduction in dopamine signaling in the motor control pathways, similar to what occurs in Parkinson's disease. - This reduction in dopamine activity can result in side effects like muscle tremors, rigidity, akinesia (difficulty initiating voluntary movements), and speech impairment, which resemble the motor symptoms seen in Parkinson's disease. 4. **Extrapyramidal Symptoms (EPS)**: - The motor side effects associated with antipsychotic drugs like chlorpromazine are collectively known as extrapyramidal symptoms (EPS). These symptoms can range from mild to severe and significantly impact a patient's quality of life. To mitigate these side effects, newer antipsychotic medications, called atypical antipsychotics, have been developed. These drugs target a broader range of neurotransmitter receptors and have a lower propensity to cause EPS compared to typical antipsychotics like chlorpromazine. However, the choice of antipsychotic medication is made by a healthcare provider based on the specific needs and response of the individual patient. Additionally, medical interventions or adjustments in medication can help manage EPS when they occur in patients taking typical antipsychotics.