Specific Opioid Receptor Subtype Identified as Key to Weight Loss Drug Effects
Opioid antagonists that promoted weight loss in rats had high affinity for the kappa-2B binding site, while non-weight-loss compounds did not.
Quick Facts
What This Study Found
Weight-loss-promoting phenylpiperidine antagonists like LY255582 had high affinity for the kappa-2B binding site. Non-weight-loss compounds did not.
Key Numbers
How They Did This
Phenylpiperidine opioid antagonists were tested for receptor binding at multiple opioid binding sites and compared based on their weight loss efficacy in lean and obese Zucker rats.
Why This Research Matters
This identifies a specific opioid receptor subsite involved in appetite and weight control. Targeting this site could lead to new weight loss drugs.
The Bigger Picture
Obesity is a global health crisis. Identifying that a specific opioid receptor subtype controls appetite and weight opens the door to targeted weight loss drugs that don't affect pain or mood.
What This Study Doesn't Tell Us
Animal study with binding data. Kappa-2B subtype classification was debated and not universally accepted. Mechanism of weight loss not fully established.
Questions This Raises
- ?Could kappa-2B-selective drugs become practical weight loss medications?
- ?Is the kappa-2B site involved in food reward and eating behavior?
Trust & Context
- Key Stat:
- Kappa-2B selectivity Only opioid antagonists with kappa-2B affinity promoted weight loss; those without it didn't, despite similar overall opioid binding
- Evidence Grade:
- Preliminary — animal binding and weight loss study. The kappa-2B subtype classification was debated in the field.
- Study Age:
- Published in 1993 (33 years ago). The opioid system's role in appetite regulation is now well-established, though receptor subtype classifications have evolved.
- Original Title:
- Phenylpiperidine opioid antagonists that promote weight loss in rats have high affinity for the kappa 2B (enkephalin-sensitive) binding site.
- Published In:
- Peptides, 14(1), 17-20 (1993)
- Authors:
- Rothman, R B(3), Xu, H(2), Char, G U, Kim, A, De Costa, B R, Rice, K C, Zimmerman, D M
- Database ID:
- RPEP-00274
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
How are opioids connected to weight?
The opioid system is involved in food reward — the pleasure of eating. Blocking specific opioid receptors can reduce the rewarding aspects of food, leading to decreased food intake and weight loss.
Why does the receptor subtype matter?
Not all opioid receptors affect appetite equally. This study shows the kappa-2B subtype is specifically involved. Targeting it selectively could produce weight loss without affecting pain relief or mood.
Read More on RethinkPeptides
Cite This Study
https://rethinkpeptides.com/research/RPEP-00274APA
Rothman, R B; Xu, H; Char, G U; Kim, A; De Costa, B R; Rice, K C; Zimmerman, D M. (1993). Phenylpiperidine opioid antagonists that promote weight loss in rats have high affinity for the kappa 2B (enkephalin-sensitive) binding site.. Peptides, 14(1), 17-20.
MLA
Rothman, R B, et al. "Phenylpiperidine opioid antagonists that promote weight loss in rats have high affinity for the kappa 2B (enkephalin-sensitive) binding site.." Peptides, 1993.
RethinkPeptides
RethinkPeptides Research Database. "Phenylpiperidine opioid antagonists that promote weight loss..." RPEP-00274. Retrieved from https://rethinkpeptides.com/research/rothman-1993-phenylpiperidine-opioid-antagonists-that
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.