“…There are currently five genetically defined MR subtypes that have been cloned and expressed in multiple types of cells, designated as m1-m5 and four subtypes of pharmacologically characterised MR, named as M1-M4 (for review, see Bonner, 1989 (Araujo et al, 1988;Aubert et al, 1992a;Caulfield et al, 1982;Dekosky et al, 1992;Lange et al, 1989;Mash et al, 1985;Palacios, 1982;Probst et al, 1988;Quirion et al, 1989;Rinne et al, 1989;Vanderheyden et al, 1987), decreases (Araujo et al, 1988;Nordberg et al, 1992;Perry et al, 1987b;Rinne et al, 1989), or increases (Aubert et al, 1992a;Svensson et al, 1992 Perry et al, 1990), decreases (Araujo et al, 1988;Aubert et al, 1992b;Mash et al, 1985;Perry et al, 1987b;Quirion et al, 1986Quirion et al, , 1989Rinne et al, 1989;Wang et al, 1989), and no changes (Aubert et al, 1992b;Svensson et al, 1992) have been described in cortical areas of AD brains as compared with control brains.…”