Patent ID: 7476508

Claim:
A method of screening for a substance for improving memory, a substance for improving learning ability, and/or a substance for treating dementia, comprising the steps of: (a) in the presence of pregnenolone sulfate, bringing a test substance into contact with a screening tool, wherein said screening tool exhibits calcium ion-permeable ion channel activity upon activation with the pregnenolone sulfate and comprises at least one of: (1) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 2, 4, or 6, (2) a polypeptide comprising the amino acid sequence of SEQ ID NO: 2, 4, or 6, and exhibiting calcium ion-permeable ion channel activity upon activation with pregnenolone sulfate, (3) a polypeptide consisting of the amino acid sequence having 98% or more homology with that of SEQ ID NO: 2, 4, or 6, and exhibiting calcium ion-permeable ion channel activity upon activation with pregnenolone sulfate, or (4) a cell expressing at least one of the polypeptides (1) to (3), (b) measuring the calcium ion-permeable ion channel activity of said screening tool following contact with the test substance, (c) comparing the pregnenolone sulfate-mediated activation of the calcium ion-permeable channel activity of the screening tool obtained in the presence of the test substance to the pregnenolone sulfate-mediated activation of the calcium ion-permeable channel activity of the screening tool obtained in the absence of the test substance, and (d) selecting a test substance that enhances the pregnenolone sulfate-mediated calcium ion-permeable ion channel activity of the screening tool and thereby identifying a substance for improving memory, a substance for improving learning ability, and/or a substance for treating dementia.