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Adenohypophysial allografts releasing prolactin decrease prolactin mRNA concentration in the host hamster's
G T Campbell1, A C Gore, M J Woller
1Department of Cell Biology and Neuroscience, University of South Carolina School of Medicine, Columbia 29208, USA.
Neuroendocrinology
|May 1, 1996
Summary
Pituitary allografts that increase prolactin (PRL) reduce host PRL mRNA levels. This study shows that PRL, not other pituitary factors, mediates this short-loop negative feedback, decreasing PRL mRNA concentration.
Area of Science:
- Endocrinology
- Molecular Biology
- Neuroscience
Background:
- Pituitary allografts are known to affect the prolactin (PRL)-secretory system.
- The mechanism by which pituitary allografts influence PRL secretion is not fully understood.
- Previous assumptions suggested elevated PRL release from allografts causes these inhibitory effects.
Purpose of the Study:
- To investigate if adult pituitary allografts, which elevate serum PRL, decrease host PRL mRNA.
- To determine if neonatal pituitary or muscle allografts, which do not elevate serum PRL, share this effect.
- To assess if these allografts alter host growth hormone mRNA levels.
Main Methods:
- Utilized Golden Syrian hamsters with pituitary allografts (adult or neonatal) or muscle allografts.
- Measured serum PRL levels and PRL mRNA concentration in the host adenohypophysis.
- Also quantified growth hormone mRNA in the host adenohypophysis.
Main Results:
- Adult pituitary allografts elevated serum PRL and decreased adenohypophysial PRL mRNA.
- Neonatal pituitary or muscle allografts did not elevate serum PRL or decrease PRL mRNA compared to sham transplants.
- No significant differences in PRL concentration within the pituitary glands or in growth hormone mRNA were observed across groups.
Conclusions:
- Demonstrates for the first time that short-loop feedback of prolactin (PRL) involves a decrease in PRL mRNA concentration.
- Supports the hypothesis that PRL itself, rather than another pituitary factor, mediates this negative feedback.
- Highlights the role of PRL in regulating its own gene expression via a short-loop feedback mechanism.