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Behavioral effects of opiates: a pharmacogenetic analysis
Current Developments in Psychopharmacology
|January 1, 1981
Summary
Opiate effects on behavior, like running activity and pain relief, vary significantly between mouse strains. These effects are distinct and influenced by neurochemistry and environmental factors.
Area of Science:
- Pharmacogenetics
- Neuroscience
- Behavioral Pharmacology
Background:
- Opiates, such as morphine and heroin, exhibit varied behavioral effects across different animal species and strains.
- Inbred mouse strains, like C57BL/6J and DBA/2J, display distinct neurochemical profiles, particularly in cholinergic and adrenergic systems, influencing opiate responses.
Purpose of the Study:
- To explore the pharmacogenetic basis of opiate effects by examining behavioral, neurophysiological, and biochemical correlates in different mouse strains.
- To investigate the relationship between motor activity and analgesia induced by opiates.
- To differentiate the neurophysiological mechanisms underlying the motor and analgesic effects of morphine.
Main Methods:
- Comparative analysis of behavioral, neurophysiological (ECoG), and biochemical responses to opiates in various inbred mouse strains.
- Utilizing mice with septal lesions alongside normal mice to dissect morphine's effects.
- Examining the influence of prior experience (naive vs. experienced animals) on morphine's stimulant effects.
Main Results:
- Opiate effects on running activity and analgesia are strain-dependent, with a negative correlation observed between these two measures.
- Morphine's motor and analgesic effects are distinct phenomena, supported by experiments in lesioned and normal mice.
- Differences in electrocorticogram (ECoG) responses to morphine were noted between strains, suggesting a link between behavioral activation and sleep-like ECoG patterns.
- Morphine administration can cause a dissociation between ECoG and behavior, similar to anticholinergic drugs.
- Environmental factors, specifically prior exposure to testing apparatus, modulate morphine's stimulant effects.
Conclusions:
- Opiate response is significantly influenced by genetic background (strain differences) and neurochemical variations.
- Motor and analgesic effects of opiates are mediated by distinct neurobiological pathways.
- Environmental context and prior experience play a crucial role in shaping the behavioral outcomes of opiate administration.