Figure 2

Sex bias in circulating GH patterns in rats and humans (note that the y axes in the human panels are logarithmic). In rats (panels A and B on left side), male pattern is “pulsatile” with low interpulse levels; female pattern is “more continuous” with higher frequency of pulses and with GH levels of “non-zero” between pulses. In humans (panels A and B on the right side), males are pulsatile with low interpulse levels, but in human females, the interpulse levels are high. (Rat data shown are adapted from ref. (62) in compliance with the terms of usage of the Proceedings of the National Academy of Sciences, USA; human data shown are adapted from ref. (56) with permission of The Endocrine Society). Additionally, insets in the rat data panels show sex-biased expression of CYP species by Western blotting, especially the male-specific expression of the 3A subfamily (3A2) (62). For comparison, in mice, M and F pulse heights are similar, the frequency is higher in F and interpulse levels can be low in both M and F (ref. (55); not shown).