Stereotaxic delivery of corticosterone onto the amygdala produces colorectal hypersensitivity through activation of lumbosacral spinal neurons. Since corticosterone activates both the mineralocorticoid (MR) and glucocorticoid (GR) receptors, the aim of this study was to determine the importance of MRs in the regulation of colorectal hypersensitivity, through the use of aldosterone that preferentially binds to MRs. Fischer-344 rats received either aldosterone (n=18) or cholesterol (control, n=18)-containing micropellets bilaterally placed stereotaxically on the dorsal margin of the amygdala. After one week, colorectal sensitivity to distension (30 mmHg) was measured in a subgroup of rats (n=8/group). In other rats (n=10/group), extracellular potentials of single L₆-S₁ spinal neurons in response to CRD (10-80 mmHg) were recorded. In aldosterone-implanted rats, CRD produced a greater visceromotor behavioral response compared to cholesterol controls (19±0.5 vs. 11.5±2.7; P<0.01). 68/182 (37%) and 56/167 (34%) of spinal neurons responded to noxious CRD in aldosterone-implanted and control groups, respectively. 36/42 (86%) neurons excited by CRD had spontaneous activity in aldosterone-implanted groups compared to control (19/33, 58%, P<0.01). Neurons with low thresholds for excitatory responses to CRD were seen more frequently in aldosterone-implanted than those in the control group (35/39 vs 18/31, P<0.05). Maximal excitatory responses of neurons to CRD in aldosterone-implanted rats were significantly greater (23.9±2.2 vs 16.4±2.0 imp/s, P<0.05) and the durations were longer (34.3±2.7 vs 24.9±1.4 s, P<0.05) than those in control group. Finally, a greater number of neurons had wide dynamic range responses to somatic stimulation in aldosterone-treated rats compared to cholesterol controls. Our findings suggest that, in the amygdala, MR-receptor mediated mechanisms are likely involved in descending pathways onto lumbosacral spinal neurons that induce colorectal hypersensitivity to luminal distension.