title: Distinct effects of testosterone on plasma and cerebrospinal fluid amyloid-beta levels.
abstract: The effect of testosterone on the levels of the Alzheimer's disease amyloid-beta peptide (Abeta) was investigated in guinea pigs. Castrated guinea pigs (GPX) were administered testosterone at two different dosages, following which plasma and cerebrospinal fluid (CSF) Abeta_{40} levels were measured. Plasma Abeta_{40} levels were reduced in GPX in the early stages of low-dose testosterone treatment, whereas CSF Abeta_{40} levels were only reduced by the time circulating testosterone had returned to untreated GPX levels. The supraphysiological testosterone dose did not reduce CSF Abeta_{40} levels significantly until circulating testosterone was back to uncastrated levels, whereas plasma Abeta_{40} levels significantly increased over time in these animals. These results indicate that the extent of testosterone-induced changes to Abeta_{40} levels and their response rates depend on both the tissue examined and testosterone dosage.
authors.affiliation: Centre of Excellence for Alzheimer's Disease Research and Care, School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia.
authors.forename: Eka J
authors.initials: EJ
authors.lastname: Wahjoepramono
authors.forename: Linda K
authors.initials: LK
authors.lastname: Wijaya
authors.forename: Kevin
authors.initials: K
authors.lastname: Taddei
authors.forename: Georgia
authors.initials: G
authors.lastname: Martins
authors.forename: Matthew
authors.initials: M
authors.lastname: Howard
authors.forename: Karl
authors.initials: K
authors.lastname: de Ruyck
authors.forename: Kristyn
authors.initials: K
authors.lastname: Bates
authors.forename: Satvinder S
authors.initials: SS
authors.lastname: Dhaliwal
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Verdile
authors.forename: Malcolm
authors.initials: M
authors.lastname: Carruthers
authors.forename: Ralph N
authors.initials: RN
authors.lastname: Martins
mesh_terms: D000544:Alzheimer Disease / Q000097:blood* / Q000134:cerebrospinal fluid*; D016564:Amyloid beta-Protein Precursor / Q000097:blood / Q000134:cerebrospinal fluid / Q000187:drug effects; D000818:Animals; D002369:Castration; D006168:Guinea Pigs; D008297:Male; D013739:Testosterone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D016564:Amyloid beta-Protein Precursor; D013739:Testosterone