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 mus carinic acetylcholinergic receptor (mACh-R) due to aging by using C-11-N-me thyl-4-piperidyl benzilate(C-11-NMPB) and positron emission tomography (PET ). The subjects consisted of 37 (20 males and 17 females) healthy volunteer s. The C-11-NMPB uptake was evaluated by the ratio method (regional C-11-NM PB uptake/Cerebellar C-11-NMPB uptake; rNMPB ratio). The correlation betwee n sex, aging, and the rNMPB ratio in normal aging was evaluated by a multip le 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 r atio might thus possibly decline with age more rapidly in females. Our stud y therefore revealed the existence of sex-related differences in the cerebr al mACh-R.