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Neuroendocrinology Letters incl. Psychoneuroimmunology & Chronobiology


NeuroendocrinologyİLetters incl. Psychoneuroimmunology & Chronobiology,
ISSNİ0172ñ780X Copyrightİ©İ1998, 1999, 2000, 2001 NeuroendocrinologyİLetters

NEL VOL. 19 No. 3

1998; 19:125-137


Effects of Aldosterine Replacement on the Radial Arm Maze Performance of Adrenalectomized Rats
by Paul R. Vaher & Bruce S. McEwen

Key words:

adrenalectomy; spatial memory; radial arm maze; dentate gyrus; aldosterone; adrenal steroids


Because our earlier study showed that adrenalectomy (ADX) caused lasting deficits in radial arm maze (RAM) performance, without a significant loss of granule cell neurons, we admininistered aldosterone (ALDO), a selective type 1 adrenal steroid receptor agonist, in an atempt to reverse RAM deficits in ADX rats. ALDO was delivered to ADX rats by osmotic minipump (10 mg/hr for 7 days, s.c.). Intake of 3% saline was measured as an index of serum levels of adrenal steroids. Sham, ADX and ADX rats receiving ALDO were tested on the RAM 4 times a week for 3 weeks. ALDO improved RAM performance in ADX rats as was especially evident in the number of errors made. Improved performance with ALDO treatment was correlated with a reduction in saline intake. Performance deteriorated during the third week in conjunction with an increase in salt appetite. In this, as well as our previous experiment, ADX resulted in only a modest increase in apoptotic neuronal death in the dentate gyrus measured 5 wks after surgery. Cross sectional dentate gyrus area was not reduced in ADX rats. Thus, type 1 receptor activation diminished spatial memory deficits in ADX rats. Our studies suggest that adrenal steroids themselves exert activational effects on spatial memory in the absence of pervasive degeneration of dentate gyrus granule cells.

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