Fig. 4.

PRG metabolism via steroidogenic enzymes are altered with age in the cerebral cortex. A: Representative Western blot showing the separation of subcellular fractions. Calnexin is a marker for the microsomal fraction, Cox4 marks the mitochondrial fraction, and NeuN marks the nuclear fraction (n = 3, with three replicate experiments). B: Representative image of the TLC plates used to separate the individual steroid metabolites. C: Dose response curve of increasing amounts ¹⁴C-PRG to ¹⁴C-metabolites in microsomes (n = 3). Data represent the average total ¹⁴C-metabolite picomoles formed per milligram of protein per hour. D: Time course of ¹⁴C-metabolite formation in microsomes following the addition of ¹⁴C-PRG (n = 3). E–J: Metabolite formation of 5α-dihydroprogesterone (5αDHP) (E), 17α-hydroxyprogesterone (17αOHP) (F), deoxycorticosterone (DOC) (G), AlloP (H), testosterone (Test) (I), and CORT (J) in microsomes isolated from the cerebral cortex of young (3 months), middle-aged (12 months), and old (24 months) mice. PRG metabolite formation is shown as the picomoles of each ¹⁴C-metabolite formed per milligram of microsomal protein per hour (n = 4 per group; one-way ANOVA) (*P < 0.05). Statistics were adjusted for multiple comparisons. Only significant differences are depicted in the figure. Data are presented as mean ± SEM