DHT is generated from testosterone by SRD

DHT is generated from testosterone by SRD5A1 [14]. Rat immature Leydig Epibrassinolide are a good model for investigating the effects of GOS on DHT production. Rat immature Leydig cells contain DHT synthetic enzyme SRD5A1 (encoded by Srd5a1) [15,16] and metabolizing enzymes 3α-hydroxysteroid dehydrogenase (encoded by Akr1c14) [15], and RDH2 (encoded by Rdh2) [16,17] and can secrete androstanediol after the catalysis of SRD5A1 and AKR1C14 (Fig. 1). We hypothesized that GOS inhibited SRD5A1, AKR1C14, and RDH2 and controlled the intracellular level of DHT. In the present study, rat SRD5A1, AKR1C14, and RDH2 were expressed in COS-1 cells. The potency and mode of action of GOS to inhibit these enzymes in both expressed enzyme preparations and rat immature Leydig cells were examined. Molecular docking study of GOS on the crystal structure of AKR1C14 was performed.
Materials and methods
Results
Discussion GOS potently inhibited SRD5A1 in COS-1 cells (Fig. 4A) and rat Leydig cells (Fig. 4B), possibly attenuating testosterone activation into DHT. It has been reported that gossypol inhibited human SRD5A1 with IC50 of 7 × 10−6 M [28]. Interestingly, gossypol preferred to block human SRD5A1 to SRD5A2 (IC50 = 21 × 10−6 M [28]. GOS exerted a noncompetitive inhibition on SRD5A1 against testosterone, indicating that it reduces SRD5A1 activity after binding equally well to the enzyme whether or not it has already bound to NADPH. GOS potently inhibited AKR1C14 (Fig. 4C and Fig. 4D). GOS inhibited AKR1C14 against DHT and NADPH cofactor in a mixed mode. Interestingly, GOS blocked several steroidogenic enzymes, including rat and human 3β-hydroxysteroid dehydrogenase [22], 17β-hydroxysteroid dehydrogenase 3 [22], 11β-hydroxysteroid dehydrogenase 1 [29] and 11β-hydroxysteroid dehydrogenase 2 [29], and placental 3β-hydroxysteroid dehydrogenase 1 [5] and aromatase [5]. However, whether it is a competitive or noncompetitive inhibitor depended upon the nature of the steroidogenic enzymes. Interestingly, GOS has lower energy to bind to the AKR1C14 than DHT, suggesting that it is potent inhibitor. Indeed, it inhibited AKR1C14 with IC50 value of 0.524 ± 0.064 × 10−6 M (Fig. 4C). Molecular docking study showed that GOS mostly bound to steroid-binding site. However, it also extends to the NADPH binding site, possibly explaining the mixed mode of inhibition by this compound.
Introduction Neurodegenerative diseases as multifactorial disorders depend on various cellular mechanism such as mitochondrial dysfunction, neuroinflammation, glutamate excitatory, oxidative stress, disruption in iron hemostasis and lipid synthesis, protein aggregation and failure of autophagy. Mitochondrial dysfunction and lipid accumulation in the brain have close cross talking with each other during neurodegeneration (Jodeiri Farshbaf et al., 2016b, Schwall et al., 2012). disruption in lipid hemostasis which is caused lipid accumulation in the brain could be hallmark for some neurological diseases (Walter and van Echten-Deckert, 2013, Kim et al., 2015). Intracellular lipid droplets (LDs) are the dynamic organelles which store lipids such as triacylglycerol and cholesterol esters and more intense in the adipose tissue (Greenberg et al., 2011). In neurodegenerative disorders high amount of ROS triggers lipid accumulation in neurons (Liu et al., 2015). Transportation of lipids in nervous system is regulated by apolipoproteins E and D (ApoE, D) (Huang and Mahle, 2014). Cellular stress, including inflammation and oxidative stress have potential roles in LDs biogenesis and formation (Khatchadourian et al., 2012, Younce and Kolattukudy, 2012). Therefore, LD formation could be the biomarker for neurodegeneration by the presentation of clinical symptoms (Liu et al., 2015). In this review, we document that focusing on the mitochondrial complex II could reveal new targets for therapeutic drug development for neurodegenerative disorders because of its potential in lipid metabolism.