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Relaxin and drinking in pregnant rats
D J Hornsby1, B C Wilson, A J Summerlee
1Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, N1G 2W1, Canada.
Progress in Brain Research
|October 9, 2001
Summary
Brain relaxin influences cardiovascular thresholds and drinking behavior in pregnant rats. This peptide interacts with the forebrain angiotensin system, impacting pregnancy physiology.
Area of Science:
- Neuroendocrinology
- Reproductive Physiology
Background:
- Relaxin, a hormone primarily from the ovary during pregnancy, is also found in the brain.
- Pregnancy is associated with altered cardiovascular regulation and fluid balance.
Purpose of the Study:
- To investigate the role of brain relaxin in cardiovascular regulation during pregnancy in rats.
- To explore the interaction between brain relaxin and the forebrain angiotensin system.
Main Methods:
- Administration of exogenous relaxin into the brain and its effects on drinking behavior.
- Use of monoclonal antibodies to neutralize endogenous brain relaxin.
- Assessment of angiotensin II AT1 receptor expression in the subfornical organ.
Main Results:
- Central administration of relaxin induced a significant drinking response, blocked by anti-relaxin antibodies.
- Neutralizing brain relaxin inhibited the normal increase in nocturnal drinking during late pregnancy.
- Blockade of angiotensin II receptors negated central relaxin actions.
- Increased angiotensin II AT1 receptor expression in the subfornical organ during pregnancy was dependent on endogenous brain relaxin.
Conclusions:
- Brain relaxin plays a role in modulating cardiovascular thresholds and fluid intake in pregnant rats.
- Relaxin's central actions are mediated via the forebrain angiotensin system, specifically at the subfornical organ.
- These findings suggest a novel mechanism for relaxin in maintaining pregnancy homeostasis.
