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Updated: May 19, 2026
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A Procedure to Study the Effect of Prolonged Food Restriction on Heroin Seeking in Abstinent Rats
Published on: November 11, 2013
Impact of Age on Heroin Intravenous Self-Administration in Wistar Rats
Michael A Taffe1, Sydney L Mehl1, Yanabel Grant1
1Department of Psychiatry, University of California, San Diego; La Jolla, CA, USA.
Biorxiv : the Preprint Server for Biology
|May 18, 2026
Summary
Opioid reward effects differ with age and sex in rats. Middle-aged male rats showed diminished opioid reward, suggesting age-related biological factors influence drug use. This research validates using middle-aged rats for opioid studies.
Area of Science:
- Neuroscience
- Pharmacology
- Addiction Research
Background:
- Rising opioid overdose and non-medical use rates are noted in middle-aged men.
- Factors driving these trends, whether biological or socio-cultural, remain unclear.
- Rodent models offer a way to differentiate these factors, but data on middle-aged rats is scarce.
Purpose of the Study:
- To investigate age-related differences in opioid anti-nociceptive and rewarding effects.
- To compare opioid responses in adult versus middle-aged rats.
Main Methods:
- Wistar rats (male and female) were tested across 4-11 months of age.
- Heroin's anti-nociceptive effects were assessed using a warm-water tail withdrawal assay.
- Intravenous self-administration (IVSA) of heroin was initiated in early adulthood (5 months) or middle age (12 months).
Main Results:
- Heroin's anti-nociceptive effects were consistent across ages.
- Female rats consistently self-administered more heroin than males, regardless of age group.
- Middle-aged male rats self-administered less heroin than adult males, indicating diminished reward.
Conclusions:
- Opioid reward is reduced in middle-aged male rats compared to younger adults.
- Middle-aged rats are suitable models for studying opioid-related behaviors, including drug seeking via IVSA.
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