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Background: The primary function of testicular Leydig cells (LCs) is to produce testosterone (T). In vitro culture of the cells represents a very important approach to study androgen production and its regulations. Various methods have been developed for the enrichment of the cells from the testes. However, getting cells in large numbers with high purity and viability is still challenging. Here, we describe a new way to isolate LCs from rat testes in large quantity with high purity and viability. Methods: Enzymatic digested testicular cells from adult rats were labelled with prolactin receptor (PRLR) antibody. The positive cells were isolated by magnetic‐activated cell sorting (MACS) protocol. Purified LCs were tested in vitro for their steroidogenic (T production) and non‐steroidogenic (25‐OH‐vitamin D production and Insl3 and Cyp2r1expressions) functions in the presence of Luteinizing Hormone (LH) for up to 24 h. Results: Reanalysis of scRNA‐seq data indicates that Prlr expression is highly specific in LCs of adult rat testis. MACS procedure based on PRLR expression was able to isolate LCs with very high yield (about 106 cells/testis), high purity (about 95%) and viability (> 93%). Purified LCs retained high steroidogenic and non‐steroidogenic functions in responding to maximal LH stimulations, with more than 10‐fold increases in T production in 3 h and 42% and 103% increases in Insl3 and Cyp2r1 expressions in 24 h. Discussion and conclusion: We have established an excellent way to purify high quality LCs from adult rat testis that can serve as a useful tool to study the physiology, pharmacology and toxicology of the cells in vitro. [ABSTRACT FROM AUTHOR]

Background: Midazolam is a neurological drug with diverse functions, including sedation, hypnosis, decreased anxiety, anterograde amnesia, brain-mediated muscle relaxation, and anticonvulsant activity. Since it is frequently used in children and adolescents for extended periods of time, there is a risk that it may affect their pubertal development. Here, we report a potential effect of the drug on the development of Leydig cells (LCs), the testosterone (T)-producing cells in the testis. Methods: Stem LCs (SLCs), isolated from adult rat testes by a magnetic-activated cell sorting technique, were induced to differentiate into LCs in vitro for 3 weeks. Midazolam (0.1–30 μM) was added to the culture medium, and the effects on LC development were assayed. Results: Midazolam has dose-dependent effects on SLC differentiation. At low concentrations (0.1–5 μM), the drug can mildly increase SLC differentiation (increased T production), while at higher concentrations (15–30 μM), it inhibits LC development (decreased T production). T increases at lower levels may be due to upregulations of scavenger receptor class b Member 1 (SCARB1) and cytochrome P450 17A1 (CYP17A1), while T reductions at higher levels of midazolam could be due to changes in multiple steroidogenic proteins. The uneven changes in steroidogenic pathway proteins, especially reductions in CYP17A1 at high midazolam levels, also result in an accumulation of progesterone. In addition to changes in T, increases in progesterone could have additional impacts on male reproduction. The loss in steroidogenic proteins at high midazolam levels may be mediated in part by the inactivation of protein kinase B/cAMP response element-binding protein (AKT/CREB) signaling pathway. Conclusion: Midazolam has the potential to affect adult Leydig cell (ALC) development at concentrations comparable with the blood serum levels in human patients. Further studies are needed to test the effects on human cells. [ABSTRACT FROM AUTHOR]

Stem Leydig cells (SLCs) play a critical role in the development and maintenance of the adult Leydig cell (ALC) population. SLCs also are present in the adult testis. Their identification, characteristics, and regulation in the adult testis remain uncertain. Using single-cell RNA-seq, we found that the mesenchymal stromal population may be involved in ALC regeneration. Upon ALC elimination, a fraction of stromal cells begins to proliferate while a different fraction begins to differentiate to ALCs. Transcriptomic analysis identified five stromal clusters that can be classified into two major groups representing proliferation and differentiation populations. The proliferating group represents stem cells expressing high levels of CD90, Nes, Lum, Fn and Gap43. The differentiating group represents a progenitor stage that is ready to form ALCs, and specifically expresses Vtn, Rasl11a, Id1 and Egr2. The observation that the actively dividing cells after ALC loss were not those that formed ALCs suggests that stem cell proliferation and differentiation are regulated separately, and that the maintenance of the stromal stem cell pool occurs at the population level. The study also identified specific markers for the major interstitial cell groups and potential paracrine factors involved in the regulation of SLCs. Our data suggest a new theory about SLC identity, proliferation, differentiation, and regulation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Guan, Chen, Ji, Wen, Chen, Zhao, Huang, Wang, Shao, Xie, Zhao, Chen, Tian, Lin, Zirkin, Duan, Su and Chen.)