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Hormonal and Nonhormonal Mechanisms of Sexual Differentiation of the Zebra Finch Brain: Embracing the Null Hypothesis
Published in Akira Matsumoto, Sexual Differentiation of the Brain, 2017
More convincing were experiments using fadrozole, a potent inhibitor of estrogen synthesis. Fadrozole inhibited aromatase activity by 75 to 100% in vivo and in vitro, measured in both young and adult zebra finches.64 Thus, there was no doubt about the effectiveness of this drug. However, when fadrozole or the similar aromatase inhibitor vorozole was given to males for several weeks after hatching, the brain developed to be as masculine that of control males.65–67 Males treated before hatching with fadrozole, on Days 3, 5, or 8 of embryonic life, also have a masculine neural circuit and song.68–72 These studies suggest that high levels of estrogen synthesis during development are not necessary for masculine neural development. Two studies suggest that inhibition of steroid synthesis has some demasculinizing effect. Merten and Stocker-Buschina73 found some demasculinization in two song nuclei caused by posthatching treatment with fadrozole, although the fadrozole-treated males sang and appeared to have neurons that were closer in phenotype to male that to female neurons. Posthatching treatment with the steroid synthesis inhibitor MK434 also is reported to have modest demasculinizing effects on portions of the song system,74 suggesting a role for steroids in masculine neural development. However, no study using steroid synthesis inhibitors or steroid receptor blockers has substantially prevented masculine song system development in males, despite numerous attempts with drugs administered both before and after hatching.
The relationship between circulating testosterone and inflammatory cytokines in men
Published in The Aging Male, 2019
Nur-Vaizura Mohamad, Sok Kuan Wong, Wan Nuraini Wan Hasan, James Jam Jolly, Mohd Fozi Nur-Farhana, Soelaiman Ima-Nirwana, Kok-Yong Chin
Gilliver et al. established a rodent wound healing model to investigate the effect of MK-434 as an agent blocking the conversion of testosterone to DHT in dermal repair. The systemic 5α-reductase inhibition treatment (1 mg/day) accelerated the healing process by suppressing the IL-6 production at the wound. The findings suggested that the inhibition of DHT production for 10 days could be a potential therapeutic target to hasten wound healing in elderly men [34].