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Morphine induced increases in the incorporation of 3H-thymidine into brain striatal DNA
Abstract:
3H-thymidine uptake into DNA fractions of rat brain regions was measured following in vivo administration of (methyl-3H)-thymidine and morphine. Acute morphine administration (10 mg/kg; 30 min prior to 3H-thymidine) increased incorporation of 3H-thymidine into DNA of rat striatum. This effect was antagonized by naloxone (1 mg/kg). Further, the observed change in incorporation of 3H-thymidine into DNA in striatum could not be accounted for by differences in the local availability of the label in morphinized rats. An autoradiographic study revealed that the 3H-thymidine was localized in nuclei in cells of the sub-ependymal layer lining the lateral ventricles, an area of glial cell proliferation in adult rats. No change in 3H-thymidine incorporation into DNA was observed in any area of the brain in morphine-addicted rats or in rats undergoing naloxone-precipitated withdrawal. The results indicate that opiates may induce permanent anatomical changes in the brain, including alterations of neuroglial interactions.
Insights
Acute morphine administration increases DNA synthesis in rat striatum, suggesting opiates may cause permanent brain changes. This effect, observed in glial cells, was blocked by naloxone.
Area of Science:
- Neuroscience
- Neuropharmacology
- Cell Biology
Background:
- Opiate drugs like morphine are widely used for pain management.
- Understanding the long-term effects of opiates on brain structure is crucial.
Purpose of the Study:
- To investigate the impact of acute morphine administration on DNA synthesis in rat brain regions.
- To explore potential permanent anatomical changes induced by opiates.
Main Methods:
- In vivo administration of (methyl-3H)-thymidine and morphine to rats.
- Measurement of 3H-thymidine incorporation into DNA across different brain regions.
- Autoradiographic analysis to localize label distribution.
- Administration of naloxone to assess antagonism of morphine effects.
Main Results:
- Acute morphine significantly increased 3H-thymidine incorporation into DNA in the rat striatum.
- This effect was dose-dependently antagonized by naloxone.
- Autoradiography showed 3H-thymidine localization in glial cells within the sub-ependymal layer.
- No changes were observed in morphine-addicted or naloxone-precipitated withdrawal rats.
Conclusions:
- Acute morphine administration stimulates DNA synthesis in specific rat brain areas, particularly in glial cells.
- Opiates may induce lasting anatomical alterations in the brain, affecting neuroglial interactions.
- These findings highlight potential neuroplastic changes associated with opiate use.