Nt latency (ML; time from the introduction of a receptive female to the first mount), intromission latency (IL; time from the introduction of a receptive female to the first intromission), and ejaculation latency (EL; interval between the first intromission and ejaculation). B6D2F1 hybrid males were given 4 weekly MSB tests prior to orchidectomy, and all the males ejaculated on at least 3 of the four tests. Thus, all the males were considered sexually experienced and chosen for further study. After orchidectomy, males were tested forFigure 1. Tau, synaptophysin and spinophilin levels in the medial preoptic area in 1934-21-0 web orchidectomized B6D2F1 hybrid male mice. B6D2F1 hybrid males that continued to demonstrate male sexual behavior after long-term orchidectomy (“maters”) have significantly more tau, synaptophysin and spinophilin in the MPOA (A-C) and more synaptophysin and spinophilin in the medial amygdala (D-E) than B6D2F1 hybrid males that ceased after long-term orchidectomy (“non-maters”). Between the two groups, there were no differences in tau levels in the medial amygdala or frontal cortex (data not illustrated). In addition, no differences in synaptophysin or spinophilin protein levels were observed in the frontal cortex between the two groups (data not illustrated). (*p,0.05; levels normalized with an endogenous control, b-actin). doi:10.1371/journal.pone.0069672.gDendritic Spine Density, Tau Male Sex BehaviorCorp., T9450) followed by polyclonal goat anti-mouse (1:10,000; BioRad, 170?047), polyclonal anti-spinophilin/neurabin II produced in rabbit (1:1000, Sigma-Aldrich Corp., N5162) followed by polyclonal goat anti-rabbit (1:10,000; Millipore, AP307P), or monoclonal anti-synaptophysin produced in rabbit (1:10,000; Millipore, catalog MAB368) followed by polyclonal goat antirabbit (1:10,000; Millipore, AP307P). This was followed by detection using SuperSignalH West Pico Chemiluminescent Substrate (Pierce Chemical Co.). Later, blots were reprobed with antibody against b-actin (1:50,000; Sigma-Aldrich Corp. A1978), and after rinsing, the blots were incubated for 1 h in an HRPconjugated goat anti-mouse IgG secondary antibody (1:10,000; Jackson) followed by chemiluminescent detection. The intensities of each of the candidate proteins and b-actin were visualized and quantified directly using the Bio-Rad Chemi Doc XRS+ Imager and Image Lab software (BioRad, USA). Levels of each of the proteins were then normalized to those of b-actin in each sample. Manuals of the get KS 176 BioRad Image Lab software are available on their website (http://www.bio-rad.com/).Experiment 2: MSB Before and After Orchidectomy in Tau Overexpressing MiceAnimals. Adult (,8 weeks old) transgenic male mice that overexpress tau (known as htau mice; n = 13) and littermate controls (n = 10) were purchased from the Jackson Lab (Mapttm1(EGFP)Klt Tg(MAPT)8cPdav/J; stock # 4808). These mice were developed by crossing transgenic mice (mouse line 8C) with mice targeted to be human MAPT mutants. An EGFP coding sequence was inserted into the first MAPT exon and disrupted expression of the gene and produced a cytoplasmic EGFP protein fused to the first 31 amino acids of MAPT. The transgenic allele is a PAC insert of 200?50 kb including the coding sequence, intronic regions and regulatory elements of the human MAPT gene. The founders of this line have now been crossed into the C57BL/6J line for ten generations. These mice express all six human MAPT isoforms. No endogenous mouse MAPT is d.Nt latency (ML; time from the introduction of a receptive female to the first mount), intromission latency (IL; time from the introduction of a receptive female to the first intromission), and ejaculation latency (EL; interval between the first intromission and ejaculation). B6D2F1 hybrid males were given 4 weekly MSB tests prior to orchidectomy, and all the males ejaculated on at least 3 of the four tests. Thus, all the males were considered sexually experienced and chosen for further study. After orchidectomy, males were tested forFigure 1. Tau, synaptophysin and spinophilin levels in the medial preoptic area in orchidectomized B6D2F1 hybrid male mice. B6D2F1 hybrid males that continued to demonstrate male sexual behavior after long-term orchidectomy (“maters”) have significantly more tau, synaptophysin and spinophilin in the MPOA (A-C) and more synaptophysin and spinophilin in the medial amygdala (D-E) than B6D2F1 hybrid males that ceased after long-term orchidectomy (“non-maters”). Between the two groups, there were no differences in tau levels in the medial amygdala or frontal cortex (data not illustrated). In addition, no differences in synaptophysin or spinophilin protein levels were observed in the frontal cortex between the two groups (data not illustrated). (*p,0.05; levels normalized with an endogenous control, b-actin). doi:10.1371/journal.pone.0069672.gDendritic Spine Density, Tau Male Sex BehaviorCorp., T9450) followed by polyclonal goat anti-mouse (1:10,000; BioRad, 170?047), polyclonal anti-spinophilin/neurabin II produced in rabbit (1:1000, Sigma-Aldrich Corp., N5162) followed by polyclonal goat anti-rabbit (1:10,000; Millipore, AP307P), or monoclonal anti-synaptophysin produced in rabbit (1:10,000; Millipore, catalog MAB368) followed by polyclonal goat antirabbit (1:10,000; Millipore, AP307P). This was followed by detection using SuperSignalH West Pico Chemiluminescent Substrate (Pierce Chemical Co.). Later, blots were reprobed with antibody against b-actin (1:50,000; Sigma-Aldrich Corp. A1978), and after rinsing, the blots were incubated for 1 h in an HRPconjugated goat anti-mouse IgG secondary antibody (1:10,000; Jackson) followed by chemiluminescent detection. The intensities of each of the candidate proteins and b-actin were visualized and quantified directly using the Bio-Rad Chemi Doc XRS+ Imager and Image Lab software (BioRad, USA). Levels of each of the proteins were then normalized to those of b-actin in each sample. Manuals of the BioRad Image Lab software are available on their website (http://www.bio-rad.com/).Experiment 2: MSB Before and After Orchidectomy in Tau Overexpressing MiceAnimals. Adult (,8 weeks old) transgenic male mice that overexpress tau (known as htau mice; n = 13) and littermate controls (n = 10) were purchased from the Jackson Lab (Mapttm1(EGFP)Klt Tg(MAPT)8cPdav/J; stock # 4808). These mice were developed by crossing transgenic mice (mouse line 8C) with mice targeted to be human MAPT mutants. An EGFP coding sequence was inserted into the first MAPT exon and disrupted expression of the gene and produced a cytoplasmic EGFP protein fused to the first 31 amino acids of MAPT. The transgenic allele is a PAC insert of 200?50 kb including the coding sequence, intronic regions and regulatory elements of the human MAPT gene. The founders of this line have now been crossed into the C57BL/6J line for ten generations. These mice express all six human MAPT isoforms. No endogenous mouse MAPT is d.