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Aldosterone effects on salt appetite in adrenalectomized rats
Neuroendocrinology
|January 1, 1986
Summary
Aldosterone (ALDO) is significantly more potent than corticosterone (CORT) in regulating salt intake in rats. Corticosterone partially blocks brain aldosterone uptake, suggesting specific mineralocorticoid recognition sites in the rat brain.
Area of Science:
- Neuroendocrinology
- Behavioral Neuroscience
- Pharmacology
Background:
- The rat brain possesses a mineralocorticoid recognition system influencing salt intake.
- Aldosterone (ALDO) and corticosterone (CORT) are key mineralocorticoids with potential roles in brain function.
Purpose of the Study:
- To determine the in vivo specificity of the rat brain's mineralocorticoid recognition system.
- To compare the potencies of ALDO and CORT in suppressing salt intake in adrenalectomized (ADX) rats.
Main Methods:
- Adrenalectomized rats were administered varying doses of ALDO or CORT via minipump.
- Salt intake was measured using a two-bottle preference test.
- In vivo brain uptake of 3H-ALDO was assessed using quantitative autoradiography and cell nuclei isolation, with and without CORT or RU 28318 administration.
Main Results:
- ALDO dose-dependently suppressed salt intake, while CORT did not.
- CORT (50 micrograms/h) suppressed forebrain 3H-ALDO uptake by 60-75%, particularly in the hippocampus, amygdala, and septum.
- The specific antimineralocorticoid RU 28318 blocked both ALDO's action on salt intake and brain 3H-ALDO uptake.
Conclusions:
- ALDO is at least 500-fold more potent than CORT as a mineralocorticoid in vivo.
- High in vivo 3H-ALDO uptake in specific brain regions is mediated by sites preferentially affected by CORT.
- These findings elucidate the distinct roles of ALDO and CORT in central mineralocorticoid signaling.