Sex-related differences in the muscarinic acetylcholinergic receptor in the healthy human brain - A positron emission tomography study

We evaluated the sex-related differences in the decline of the cerebral muscarinic acetylcholinergic receptor (mACh-R) due to aging by using C-11-N-methyl-4-piperidyl benzilate(C-11-NMPB) and positron emission tomography (PET). The subjects consisted of 37 (20 males and 17 females) healthy volunteers. The C-11-NMPB uptake was evaluated by the ratio method (regional C-11-NMPB uptake/Cerebellar C-11-NMPB uptake; rNMPB ratio). The correlation between sex, aging, and the rNMPB ratio in normal aging was evaluated by a multiple regression analysis. The rNMPB ratio was higher in females than in males throughout the entire cerebral region (p < 0.01-p < 0.0001) and he rNMPB ratio might thus possibly decline with age more rapidly in females. Our study therefore revealed the existence of sex-related differences in the cerebral mACh-R.