Related Experiment Videos
Effects of morphine on DNA synthesis in neonatal rat brain
Abstract:
Several observations have led to the hypothesis that endogenous opioids may modulate the growth and development of the brain. In the present study, we have examined the effect of morphine on the incorporation of [3H]thymidine into the DNA of neonatal rat brains in vivo and in vitro. We have found that morphine, when administered to one-day-old rats, inhibited [3H]thymidine incorporation into brain DNA in a long-lasting, naloxone-reversible manner. Morphine inhibited DNA synthesis in animals one and 4 days of age but not in older animals. This effect was tissue-specific, and did not appear to be due simply to respiratory depression or decreased availability of precursor to the brain. Naloxone, when administered acutely, or naltrexone, chronically, had no effect on [3H]thymidine incorporation, indicating that endogenous opioids do not tonically depress DNA synthesis. When neonatal brain tissue was incubated with morphine in vitro. [3H]thymidine incorporation values were not different from controls. These data indicate that the effect of morphine on DNA synthesis in vivo may be an indirect one, rather than a direct action on proliferating cells.
Insights
Morphine temporarily reduces DNA synthesis in neonatal rat brains, an effect reversible by naloxone. This suggests opioids may influence brain development indirectly, not by directly acting on developing brain cells.
Area of Science:
- Neuroscience
- Developmental Biology
- Pharmacology
Background:
- Endogenous opioids are hypothesized to influence brain growth and development.
- Previous observations suggest a role for opioids in neurodevelopmental processes.
Purpose of the Study:
- To investigate the effect of morphine on DNA synthesis in neonatal rat brains.
- To determine if endogenous opioids tonically affect DNA synthesis in developing brains.
Main Methods:
- Administered morphine to one-day-old and older rats, measuring [3H]thymidine incorporation into brain DNA in vivo.
- Tested naloxone and naltrexone for effects on [3H]thymidine incorporation.
- Incubated neonatal rat brain tissue with morphine in vitro to assess direct cellular effects.
Main Results:
- Morphine significantly inhibited [3H]thymidine incorporation in neonatal rat brains in a naloxone-reversible manner.
- This inhibitory effect was observed in one- and four-day-old rats but not in older animals.
- In vitro incubation of neonatal brain tissue with morphine did not alter [3H]thymidine incorporation compared to controls.
Conclusions:
- Morphine's inhibition of neonatal brain DNA synthesis in vivo is likely an indirect effect.
- Endogenous opioids do not appear to tonically suppress DNA synthesis in the developing brain.
- These findings suggest a potential indirect modulation of neurodevelopment by opioids.