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Gender differences in the cardiovascular responses to morphine and naloxone in spinal rats
1Departamento de Farmacología y Toxicología, Cinvestav, IPN, Apartado Postal 22026, 14000, D.F., Mexico City, Mexico. jcmolcruz@compuserve.com.mx
Abstract:
Putative gender differences in opiate cardiovascular effects were evaluated in spinal rats. After a 4-h exposure to a single dose of morphine (30 mg/kg, i.v.), abstinence was precipitated by naloxone (0.03-3 mg/kg, i.v.). Morphine produced a long-lasting bradycardia and a transient increase in arterial pressure that was similar in both genders. Thereafter, blood pressure decreased both in males and females. Naloxone precipitated a similar dose-dependent heart rate increase in both sexes and a gender-dependent increase in blood pressure. This sex difference appeared in the shape of the response. Prazosin (0.2 mg/kg), prior to naloxone, reduced the pressor response in all animals, suggesting a similar participation of the noradrenergic system in both genders. The present results extend to acute dependence the notion of a sex-dependent differential effect of morphine. The need to consider gender as a factor when studying the effects of opioids is highlighted.
Insights
Opioid withdrawal effects differ by sex. While morphine
Area of Science:
- Pharmacology and Toxicology
- Neuroscience
- Cardiovascular Physiology
Background:
- Opioid drugs like morphine have significant cardiovascular effects.
- Understanding potential gender differences in drug responses is crucial for personalized medicine.
Purpose of the Study:
- To investigate putative gender differences in the cardiovascular effects of morphine and naloxone-precipitated withdrawal in spinal rats.
Main Methods:
- Rats (male and female) were exposed to morphine (30 mg/kg, i.v.) for 4 hours.
- Abstinence was precipitated using various doses of naloxone (0.03-3 mg/kg, i.v.).
- Cardiovascular parameters including heart rate and arterial pressure were monitored. Prazosin was used to assess noradrenergic system involvement.
Main Results:
- Morphine induced similar bradycardia and transient hypertension in both sexes.
- Naloxone precipitated a dose-dependent heart rate increase in both sexes.
- A significant gender-dependent difference was observed in the shape of the naloxone-induced blood pressure response.
- Prazosin pretreatment similarly reduced the pressor response in both genders, indicating comparable noradrenergic system participation.
Conclusions:
- The study highlights sex-dependent differential effects of morphine during acute withdrawal.
- Gender must be considered a critical factor when evaluating opioid effects and developing treatments.