Methazolamide

Cryptorchidism, the failure of testes to descend into the scrotum, exposes the testes to higher temperature and external pressure. Scholars from Razi University found through research conducted at different pressure gradients (0, 25, 50, and 100 mmHg) and time gradients (2 and 4 h) that high hydrostatic pressure may lead to sperm apoptosis. In this work, we investigated the effect of external pressure on spermatogonia, exploring a new mechanism of male infertility caused by cryptorchidism.

Various pressure gradients (0, 25, 50, and 100 mmHg) were applied to spermatogonia for different durations (0, 2, and 4 h) in the Cell Counting Kit-8 (CCK8) experiment. Morphological changes, cell ultrastructure, apoptosis rates, and the expression of apoptosis-related proteins (bax, bcl-2, caspase-3, and caspase-9) were assessed through immunofluorescence, electron microscopy, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay, flow cytometry, immunohistochemistry, real-time quantitative polymerase chain reaction (qPCR), and western blot.

The cell viability assay showed that higher external pressure had a greater negative time-dependent impact on cell viability. Immunofluorescence results indicated that external pressure stimuli altered the morphology of spermatogonia. The results of TUNEL assay and flow cytometry demonstrated that external pressure stimuli induced apoptosis in spermatogonia. Transmission electron microscopy (TEM) observations showed the generation of apoptotic bodies, mitochondrial swelling, vacuolization, and mitochondrial cristae fusion. The results of immunohistochemistry indicated that pressure induced the expression of caspase-3 and caspase-9 proteins. qPCR and western blot analyses revealed an increased ratio of bax/bcl-2 and expression of caspase-3 and caspase-9. Methazolamide (cytochrome C inhibitor) blocked the pressure-induced cell apoptosis and inhibited the activation of caspase-3 while Z-IETD-FMK (caspase-8 inhibitor) did not.

External pressure promotes spermatogonia apoptosis through the intrinsic apoptosis pathway, which may be one of the mechanisms of male infertility induced by cryptorchidism.

Human carbonic anhydrases (hCAs) play a central role in various physiological processes in the human body. HCAs catalyze the reversible hydration of CO₂ into HCO₃^-, and hence maintains the fluid and pH balance. Overexpression of CA II is associated with diseases, such as glaucoma, and epilepsy. Therefore, CAs are important clinical targets and inhibition of different isoforms, especially hCA II is used in treatment of glaucoma, altitude sickness, and epilepsy. Therapeutically used CA inhibitors (CAI) are sulfonamide-based, such as acetazolamide, dichlorphenamide, methazolamide, ethoxzolamide, etc. However, they exhibit several undesirable effects such as numbness, tingling of extremities, malaise, metallic taste, fatigue, renal calculi, and metabolic acidosis. Therefore, there is an urgent need to identify safe and effective inhibitors of the hCAs. In this study, different phenyl boronic acids 1-5 were evaluated against bovine (bCA II) and hCA II. Among all, compound 1 (4-acetylphenyl boronic acid) was found to be active against bCAII and hCA II with IC₅₀ values of 246 ± 0.48 and 281.40 ± 2.8 μM, respectively, while the remaining compounds were found in-active. Compound 1 was identified as competitive inhibitor of hCA II enzyme (K_i = 283.7 ± 0.002 μM). Additionally, compound 1 was found to be non-toxic against BJ Human fibroblast cell line. The X-ray crystal structure for hCA II in-complex with compound 1 was evaluated to a resolution of 2.6 Å. In fact, this the first structural analysis of a phenyl boron-based inhibitor bound to hCA II, allowing an additional structure-activity analysis of the compounds. Compound 1 was found to be directly bound in the active site of hCA II by interacting with His94, His119, and Thr199 residues. In addition, a bond of 3.11 Å between the zinc ion and coordinated boron atom of the boronic acid moiety of compound 1 was also observed, contributing to binding affinity of compound 1 for hCA II. PDB ID: 8IGF.