Sigma receptor-binding agent

1. A method for inhibition of a sigma receptor, which comprises administering an alkyl ether derivative represented by the formula [1] or a salt thereof to a subject in need of inhibition of a sigma receptor:

wherein R 1 and R 2 , which are the same or different, each represent at least one member selected from the group consisting of a hydrogen atom, a halogen atom, an optionally substituted C 1-6 alkyl group, an optionally substituted aryl group, an optionally substituted ar(C 1-6 )alkyl group, an optionally substituted C 1-6 alkoxy group, an optionally substituted aryloxy group, an optionally substituted C 1-6 alkylthio group, an optionally substituted arylthio group, an optionally substituted C 2-6 alkenyl group, an optionally substituted C 2-6 alkenyloxy group, an optionally substituted C 1-6 alkylamino group, an optionally substituted C 1-6 alkylsulfonyl group, an optionally substituted arylsulfonyl group, an optionally substituted carbamoyl group, an optionally substituted heterocyclic group, an optionally protected amino group, an optionally protected hydroxyl group, an optionally protected carboxyl group, a nitro group, and an oxo group; R 3 represents an optionally substituted C 1-6 alkylamino group, an optionally protected amino group, or an optionally protected hydroxyl group; m and n, which are the same or different, each represent an integer of 1 to 6.

2. A method for inhibition of a sigma receptor, which comprises administering an alkyl ether derivative represented by the formula [1] or a salt thereof to a subject in need of inhibition of a sigma-1 receptor:

wherein R 1 and R 2 , which are the same or different, each represent at least one member selected from the group consisting of a hydrogen atom, a halogen atom, an optionally substituted C 1-6 alkyl group, an optionally substituted aryl group, an optionally substituted ar(C 1-6 )alkyl group, an optionally substituted C 1-6 alkoxy group, an optionally substituted aryloxy group, an optionally substituted C 1-6 alkylthio group, an optionally substituted arylthio group, an optionally substituted C 2-6 alkenyl group, an optionally substituted C 2-6 alkenyloxy group, an optionally substituted C 1-6 alkylamino group, an optionally substituted C 1-6 alkylsulfonyl group, an optionally substituted arylsulfonyl group, an optionally substituted carbamoyl group, an optionally substituted heterocyclic group, an optionally protected amino group, an optionally protected hydroxyl group, an optionally protected carboxyl group, a nitro group, and an oxo group; R 3 represents an optionally substituted C 1-6 alkylamino group, an optionally protected amino group, or an optionally protected hydroxyl group; m and n, which are the same or different, each represent an integer of 1 to 6.

3. The method according to claim 2 , wherein R 1 and R 2 , which are the same or different, each represent a hydrogen atom, a halogen atom, or a C 1-6 alkoxy group.

4. The method according to claim 2 , wherein m is 2 and n is 2 or 3.

5. The method according to claim 3 , wherein m is 2 and n is 2 or 3.

6. The method according to claim 2 , wherein R 3 is an optionally protected hydroxyl group.

7. The method according to claim 3 , wherein R 3 is an optionally protected hydroxyl group.

8. The method according to claim 4 , wherein R 3 is an optionally protected hydroxyl group.

9. The method according to claim 5 , wherein R 3 is an optionally protected hydroxyl group.

10. The method according to claim 2 , wherein the alkyl ether derivative is 1-(3-(2-(1-benzothiophene-5-yl)ethoxy)propyl)azetidine-3-ol.

11. A method for inhibition of a sigma receptor, which comprises administering 1 (3 (2 (1 benzothiophene-5-yl)ethoxy)propyl)azetidine-3-ol or a salt thereof to a subject in need of inhibition of a sigma-2 receptor.

12. A method for investigating the physiological function and/or activity of sigma receptors, which comprises

(i) labeling an alkyl ether derivative represented by the formula [1] or a salt thereof with a label compound;

(ii) administering the labeled alkyl ether derivative or a salt thereof to cells and/or living body; and

(iii) imaging a distribution of sigma receptor in cells and/or living body by ray and/or radiation which is released from the label compound:

wherein R 1 and R 2 , which are the same or different, each represent at least one member selected from the group consisting of a hydrogen atom, a halogen atom, an optionally substituted C 1-6 alkyl group, an optionally substituted aryl group, an optionally substituted ar(C 1-6 )alkyl group, an optionally substituted C 1-6 alkoxy group, an optionally substituted aryloxy group, an optionally substituted C 1-6 alkylthio group, an optionally substituted arylthio group, an optionally substituted C 2-6 alkenyl group, an optionally substituted C 2-6 alkenyloxy group, an optionally substituted C 1-6 alkylamino group, an optionally substituted C 1-6 alkylsulfonyl group, an optionally substituted arylsulfonyl group, an optionally substituted carbamoyl group, an optionally substituted heterocyclic group, an optionally protected amino group, an optionally protected hydroxyl group, an optionally protected carboxyl group, a nitro group, and an oxo group; R 3 represents an optionally substituted C 1-6 alkylamino group, an optionally protected amino group, or an optionally protected hydroxyl group; m and n, which are the same or different, each represent an integer of 1 to 6.

13. A method for inhibition of a sigma receptor, which comprises

(i) identifying a subject in need of inhibition of a sigma receptor by analyzing an expression of sigma receptor gene in a subject and/or measuring an activity of sigma receptor in a subject; and

(ii) administering an alkyl ether derivative represented by the formula [1] or a salt thereof to the subject in need of inhibition of a sigma receptor:

wherein R 1 and R 2 , which are the same or different, each represent at least one member selected from the group consisting of a hydrogen atom, a halogen atom, an optionally substituted C 1-6 alkyl group, an optionally substituted aryl group, an optionally substituted ar(C 1-6 )alkyl group, an optionally substituted C 1-6 alkoxy group, an optionally substituted aryloxy group, an optionally substituted C 1-6 alkylthio group, an optionally substituted arylthio group, an optionally substituted C 2-6 alkenyl group, an optionally substituted C 2-6 alkenyloxy group, an optionally substituted C 1-6 alkylamino group, an optionally substituted C 1-6 alkylsulfonyl group, an optionally substituted arylsulfonyl group, an optionally substituted carbamoyl group, an optionally substituted heterocyclic group, an optionally protected amino group, an optionally protected hydroxyl group, an optionally protected carboxyl group, a nitro group, and an oxo group; R 3 represents an optionally substituted C 1-6 alkylamino group, an optionally protected amino group, or an optionally protected hydroxyl group; m and n, which are the same or different, each represent an integer of 1 to 6.