A sex hormone binding globulin (SHBG) similar to human SHBG was identified in marmoset serum based on its gel electrophoretic mobility, isoelectric point and steroid binding properties. Levels of serum SHBG were measured in immature and mature males, immature females and females during the luteal phase and pregnancy; serum progesterone, 5α-dihydrotestosterone (5α-DHT), testosterone, oestradiol-17β and oestrone were also measured. Mean (± s.e.m.) concentrations of SHBG in immature males (336 ±19 nmol/l) were higher (P <0·01) than those in mature males (251 ±13 nmol/l), whereas values in the groups of females were similar (359 ± 12, 395 ± 17, 397 ± 39 nmol/l in immature, non-pregnant and pregnant females respectively). There was an inverse relationship between SHBG and the levels of testosterone (r= −0·67) and 5α-DHT (r = −0·86) in males, but the correlation was significant (P <0·05) only for 5α-DHT. There was no correlation between levels of SHBG and oestrogens in males or between levels of SHBG and any of the steroids measured in females. Equilibrium dialysis was used to assess the percentage of steroid in serum in the unbound form. Mean percentage values for unbound testosterone and 5α-DHT were lower in immature males than in mature males (P <0·01) and negatively correlated with levels of SHBG (r = −0·78, testosterone; r = −0·56, 5α-DHT).
Foveal remapping of motion in area MT of the marmoset monkey