Related Experiment Videos
Effect of chronic neonatal morphine and naloxone on sensorimotor and social development of young rats
1Department of Psychology, Bowling Green State University, OH 43403.
Insights
Neonatal exposure to morphine delayed physical and social development in rats. Conversely, naloxone treatment during this critical period enhanced development and social behaviors.
Area of Science:
- Neuroscience
- Developmental Biology
- Pharmacology
Background:
- Neonatal opioid exposure can impact long-term neurodevelopment.
- Understanding the effects of morphine and its antagonist, naloxone, on developing systems is crucial.
Purpose of the Study:
- To investigate the effects of chronic neonatal morphine and naloxone administration on physical, motor, and social development in Long-Evans rats.
- To compare the developmental trajectories of rats exposed to morphine, naloxone, or no treatment during a critical early postnatal period.
Main Methods:
- Newborn Long-Evans rat pups were treated daily with escalating doses of morphine or a fixed dose of naloxone from postnatal days 3-26.
- Physical development (body weight, eye opening), motor coordination (catalepsy, grasping, swimming), and social behaviors (homing, play) were assessed.
Main Results:
- Chronic morphine exposure resulted in significant delays in physical development and motor coordination compared to controls.
- Morphine-treated rats showed deficits in social behaviors, including homing and play.
- Naloxone treatment led to modest improvements in physical development and did not impede social development; in fact, it accelerated homing behavior acquisition.
Conclusions:
- Neonatal morphine exposure has detrimental effects on multiple developmental domains in rats.
- Naloxone administration during the neonatal period appears to be neuroprotective, promoting development and enhancing social behaviors.
Abstract:
Chronic morphine treatment of newborn Long-Evans rat pups between 3-26 days of age (thrice daily starting with 0.5 mg/kg, increased daily by 0.5 mg/kg to 10 mg/kg) led to lags of 1 to 3 days in physical development (body weights and eye opening times) and motor coordination (catalepsy test, grasping, swimming). Chronic naloxone treatment (5 mg/kg administered thrice daily from day 3-26), in contrast, led to modest gains in development on a number of measures (body weights, vaginal opening). Morphine animals also lagged behind controls and naloxone-tested animals in social behaviors, such as homing and play. Chronic naloxone did not block or retard social development; in fact naloxone-treated animals exhibited more rapid acquisition of homing behavior than controls.