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Chronic food restriction and acute food deprivation decrease mRNA levels of opioid peptides in arcuate nucleus
E M Kim1, C C Welch, M K Grace
1Research and Medicine Service. Department of Veterans Affairs Medical Center, Minneapolis, Minnesota, USA.
The American Journal of Physiology
|May 1, 1996
Summary
Food restriction and deprivation decrease opioid gene expression in the rat arcuate nucleus. These findings suggest endogenous opioid synthesis is linked to food intake and body weight changes.
Area of Science:
- Neuroscience
- Endocrinology
- Molecular Biology
Background:
- Opioid administration stimulates food intake, but the role of endogenous opioid synthesis in regulating consumption remains unclear.
- The arcuate nucleus (ARC) is a key brain region involved in energy balance and appetite regulation.
Purpose of the Study:
- To investigate the relationship between endogenous opioid synthesis and food consumption.
- To examine the effects of food restriction and deprivation on opioid mRNA levels in the rat ARC.
Main Methods:
- Two studies were conducted using rats subjected to varying degrees of food restriction (10-40% of ad libitum intake) and deprivation (24-48 hours).
- Quantitative analysis of pro-dynorphin (proDyn), pro-enkephalin (proEnk), and pro-opiomelanocortin (POMC) mRNA levels in the ARC was performed using quantitative PCR.
Main Results:
- Food restriction and deprivation led to significant decreases in body weight.
- Opioid mRNA levels (proDyn, proEnk, POMC) in the ARC decreased in a manner directly related to the extent of food restriction and body weight loss.
- Specifically, 48-hour deprivation significantly reduced proDyn and POMC mRNA, while 24-hour deprivation reduced POMC mRNA. ProEnk mRNA was unaffected by short-term deprivation.
Conclusions:
- Endogenous opioid mRNA levels in the rat ARC are directly correlated with food intake and body weight.
- These findings elucidate a link between central opioid pathways and energy balance regulation.