Endogenous biosynthesis of docosahexaenoic acid(DHA)regulates fish oocyte maturation by promoting pregnenolone production

Omega-3 polyunsaturated fatty acids(n-3 PUFAs),particularly docosahexaenoic acid(22:6n-3,DHA),play crucial roles in the reproductive health of vertebrates,including humans.Nevertheless,the underlying mechanism related to this phenomenon remains largely unknown.In this study,we employed two zebrafish genetic models,i.e.,elovl2^(-/-)mutant as an endogenous DHAdeficient model and fat1(omega-3 desaturase encoding gene)transgenic zebrafish as an endogenous DHA-rich model,to investigate the effects of DHA on oocyte maturation and quality.Results show that the elovl2^(-/-)mutants had much lower fecundity and poorer oocyte quality than the wild-type controls,while the fat1 zebrafish had higher fecundity and better oocyte quality than wildtype controls.DHA deficiency in elovl2^(-/-)embryos led to defects in egg activation,poor microtubule stability,and reduced pregnenolone levels.Further study revealed that DHA promoted pregnenolone synthesis by enhancing transcription of cyp11a1,which encodes the cholesterol side-chain cleavage enzyme,thereby stabilizing microtubule assembly during oogenesis.In turn,the hypothalamic-pituitary-gonadal axis was enhanced by DHA.In conclusion,using two unique genetic models,our findings demonstrate that endogenously synthesized DHA promotes oocyte maturation and quality by promoting pregnenolone production via transcriptional regulation of cyp11a1.

Pregnenolone 16α-carbonitrile negatively regulates hippocampal cytochrome P450 enzymes and ameliorates phenytoin-induced hippocampal neurotoxicity

The central nervous system is susceptible to the modulation of various neurophysiological processes by the cytochrome P450 enzyme(CYP),which plays a crucial role in the metabolism of neurosteroids.The antiepileptic drug phenytoin(PHT)has been observed to induce neuronal side effects in patients,which could be attributed to its induction of CYP expression and testosterone(TES)metabolism in the hippocampus.While pregnane X receptor(PXR)is widely known for its regulatory function of CYPs in the liver,we have discovered that the treatment of mice with pregnenolone 16α-carbonitrile(PCN),a PXR agonist,has differential effects on CYP expression in the liver and hippocampus.Specifically,the PCN treatment resulted in the induction of cytochrome P450,family 3,subfamily a,polypeptide 11(CYP3A11),and CYP2B10 expression in the liver,while suppressing their expression in the hippocampus.Functionally,the PCN treatment protected mice from PHT-induced hippocampal nerve injury,which was accompanied by the inhibition of TES metabolism in the hippocampus.Mechanistically,we found that the inhibition of hippocampal CYP expression and attenuation of PHT-induced neurotoxicity by PCN were glucocorticoid receptor dependent,rather than PXR independent,as demonstrated by genetic and pharmacological models.In conclusion,our study provides evidence that PCN can negatively regulate hippocampal CYP expression and attenuate PHT-induced hippocampal neurotoxicity independently of PXR.Our findings suggest that glucocorticoids may be a potential therapeutic strategy for managing the neuronal side effects of PHT.

Rapid Microwave Assisted Synthesis and Antiproliferative Evaluation of Novel Steroidal Thiazole Derivatives

Three series of novel steroidal thiazole derivatives were synthesized by microwave assisted one-potreaction from pregnenolone, testosterone and estrone, respectively. Their structures were characterized by IR, NMRand HRMS, and the antiproliferative activities of all the synthesized compounds against human cervical carcinoma（HeLa）, human liver carcinoma（HepG2）, human lung carcinoma（A549）, nasopharyngeal carcinoma（CNE2） andnormal kidney epithelial cells（HEK293T） were screened. Among the compounds, 1-estron-17＇-ylidene-2-[4＇-（p-bromophenyl）-2＇-thiazol]hydrazone（12） displayed distinct antiproliferative activity against all the tested cancercell lines and was almost inactive to normal kidney epithelial cells.