Related Experiment Videos
A small dose of morphine increases intake of and preference for isotonic saline among rats
M Bertino1, M L Abelson, S H Marglin
1Monell Chemical Senses Center, University of Pennsylvania, Philadelphia 19104.
Abstract:
Water-deprived rats were given hourly opportunities to ingest physiological saline and water for a number of days until they were taking substantial amounts of both solutions. Prior to some opportunities to ingest, they were injected with either morphine (2.0 mg/kg) or a placebo. Across a variety of procedures, morphine increased intake of and, in 1-hr tests, increased preference for 0.9% NaCl. Intake of 1.5% NaCl also increased after administration of morphine. These data suggest that endogenous opioids are involved in sodium intake. These data also provide further support for the idea that one or more of the endogenous opioid systems are involved in the regulation of ingestion.
Insights
Morphine administration increased both the intake and preference for saline solutions in water-deprived rats. These findings indicate a role for endogenous opioids in regulating sodium appetite and overall ingestion behaviors.
Area of Science:
- Neuroscience
- Behavioral Pharmacology
- Physiology
Background:
- Opioid systems play a crucial role in regulating various physiological processes.
- Sodium appetite is a critical behavior for maintaining fluid and electrolyte balance.
- Understanding the neurobiological underpinnings of ingestive behaviors is essential for addressing related disorders.
Purpose of the Study:
- To investigate the effect of morphine on saline intake and preference in a rat model.
- To explore the potential involvement of endogenous opioid systems in sodium appetite regulation.
Main Methods:
- Water-deprived rats were provided with hourly access to water and physiological saline (0.9% NaCl).
- Rats received injections of morphine (2.0 mg/kg) or a placebo prior to ingestive opportunities.
- Intake and preference for different concentrations of NaCl (0.9% and 1.5%) were measured.
Main Results:
- Morphine administration significantly increased the intake of 0.9% NaCl.
- In 1-hour tests, morphine also enhanced the preference for 0.9% NaCl.
- Increased intake of 1.5% NaCl was observed following morphine administration.
Conclusions:
- Endogenous opioids are implicated in the regulation of sodium intake.
- Opioid systems contribute to the control of ingestive behaviors, including salt appetite.