Related Experiment Video
Updated: Aug 14, 2026
A Procedure to Study the Effect of Prolonged Food Restriction on Heroin Seeking in Abstinent Rats
Published on: November 12, 2013
Increased brain size and cellular content in infant rats treated with an opiate antagonist
Insights
Naltrexone administration in early life stimulated significant increases in body and brain growth in rats. This suggests the endorphin and opiate receptor system plays a crucial role in developmental processes.
Area of Science:
- Neuroscience
- Developmental Biology
- Pharmacology
Background:
- The role of the endorphin and opiate receptor system in mammalian development is not fully understood.
- Naltrexone is an opioid antagonist used to block the effects of opioids.
Purpose of the Study:
- To investigate the effects of early-life naltrexone exposure on physical and neurological development in rats.
- To explore the potential involvement of the endorphin and opiate system in growth regulation.
Main Methods:
- Rat offspring were administered daily naltrexone injections from birth to day 21.
- Body, brain, and cerebellar weights were measured.
- Morphometric analysis of the cerebrum and cerebellum was performed.
- Cellular composition of the cerebellum was assessed.
Main Results:
- Naltrexone-injected rats showed increased body (18%), brain (11%), and cerebellar (5%) weights compared to controls.
- Cerebral somatosensory cortex was 18% thicker in naltrexone-treated rats.
- The cerebellum was 41% larger, with 70% more glial cells and 30% more granule neurons.
- Prenatally derived neurons were unaffected.
Conclusions:
- Early-life naltrexone administration promotes significant body and brain growth in rats.
- These findings highlight a potential role for the endorphin and opiate receptor system in regulating development.
- Naltrexone's growth-stimulating effects may offer insights into developmental disorders.
Abstract:
From birth to day 21, rat offspring received daily injections of naltrexone at a dosage that blocked morphine-induced analgesia 24 hours a day. At 21 days, body, brain, and cerebellar weights of naltrexone-injected animals were 18, 11, and 5 percent greater than corresponding control weights. In addition, morphometric analysis of the cerebrum revealed a somatosensory cortex that was 18 percent thicker than that of the controls. The cerebellum of naltrexone-treated rats was 41 percent larger in total area and contained at least 70 percent more glial cells and 30 percent more granule neurons. Neurons derived prenatally were unaffected by drug treatment. These results show that naltrexone can stimulate body and brain growth in rats and suggest a role for the endorphin and opiate receptor system in development.
More Related Videos
10:05Rodent Brain Microinjection to Study Molecular Substrates of Motivated Behavior
Published on: September 16, 2015
09:54Combining Laser Capture Microdissection and Microfluidic qPCR to Analyze Transcriptional Profiles of Single Cells: A Systems Biology Approach to Opioid Dependence
Published on: March 8, 2020