Objective: Sudden unexpected death in epilepsy (SUDEP) is an unpredictable and devastating comorbidity of epilepsy that is believed to be due to cardiorespiratory failure immediately after generalized convulsive seizures. Methods: We performed cardiorespiratory monitoring of seizure-induced death in mice carrying either a p.Arg1872Trp or p.Asn1768Asp mutation in a single Scn8a allele-mutations identified from patients who died from SUDEP-and of seizure-induced death in pentylenetetrazole-treated wild-type mice. Results: The primary cause of seizure-induced death for all mice was apnea, as (1) apnea began during a seizure and continued for tens of minutes until terminal asystole, and (2) death was prevented by mechanical ventilation. Fatal seizures always included a tonic phase that was coincident with apnea. This tonic phase apnea was not sufficient to produce death, as it also occurred during many nonfatal seizures; however, all seizures that were fatal had tonic phase apnea. We also made the novel observation that continuous tonic diaphragm contraction occurred during tonic phase apnea, which likely contributes to apnea by preventing exhalation, and this was only fatal when breathing did not resume after the tonic phase ended. Finally, recorded seizures from a patient with developmental epileptic encephalopathy with a previously undocumented SCN8A likely pathogenic variant (p.Leu257Val) revealed similarities to those of the mice, namely, an extended tonic phase that was accompanied by apnea. Interpretation: We conclude that apnea coincident with the tonic phase of a seizure, and subsequent failure to resume breathing, are the determining events that cause seizure-induced death in Scn8a mutant mice.

Methoxychlor (MXC), an organochloride insecticide, is a potent toxicant-targeting female reproductive system and known to cause follicular atresia by inducing apoptosis within granulosa cells. Oxidative stress plays a pivotal role in apoptosis; thus, this study focuses on the ameliorative action of N-acetyl cysteine (NAC) on MXC-induced oxidative stress and apoptosis within granulosa cell of caprine ovary. Classic histology, fluorescence assay, and biochemical parameters were employed to evaluate the effect of varied concentration of NAC (1, 5, and 10 mM) on granulosa cell apoptosis after 24, 48, and 72 h exposure duration. Histomorphological studies revealed that NAC diminished the incidence of apoptotic attributes like condensed or marginated chromatin, pyknosis, crescent-shaped nucleus, empty cell spaces, and degenerated cellular structure along with the presence of cytoplasmic processes within granulosa cells in dose- and time-dependent manner. NAC significantly downregulated the percentage of MXC-induced granulosa cell apoptosis within healthy ovarian follicle with its increasing dose, maximum at 10 mM concentration. It also significantly (p < 0.05) upregulated the activity of antioxidant enzymes, namely catalase, superoxide dismutase, and glutathione-s-transferase, along with ferric reducing antioxidant power further declining lipid peroxidation in the MXC-treated caprine ovary. The results revealed a negative correlation between apoptosis frequency and antioxidant enzymes' activity (r = -0.67, r = -0.56, r = -0.31; p < 0.05) while a positive correlation was observed with lipid peroxidation (r = 0.63; p < 0.05) after NAC supplementation. Thus, NAC supplementation reduces the MXC-generated oxidative stress that perhaps declines the ROS generating signal transduction pathway of apoptosis, thereby preventing MXC-induced granulosa cell apoptosis and follicular atresia. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 156-166, 2017.

Toxicological studies have demonstrated the exposure-risk relationship of several pesticides on reproduction of living organisms. To evaluate the role of malathion as a reproductive toxicant, this study aims at assessing the cytological and biochemical changes in the granulosa cells after malathion exposure in dose (1 nM, 10 nM, 100 nM) and time (4 h, 6 h, 8 h) dependent manner. Histomorphological analysis, fluorescence assay, apoptosis quantification, and terminal deoxynucleotidyl transferase d-UTP mediated nick end labeling (TUNEL) assay were done to determine cytological changes, whereas antioxidant enzyme assays were done to measure the oxidative stress in malathion treated ovarian antral follicles. Histological studies exhibited the occurrence of highly condensed or marginated chromatin with fragmented nucleus, pyknosis, loss of membrane integrity, increased empty spaces, and vacuolization in malathion treated granulosa cells. Ethidium bromide/acridine orange (EB/AO) fluorescence staining demonstrated a significant increase in incidence and percentage of apoptosis after malathion exposure (p < 0.001), both between and within the groups. Malathion exposure also resulted in increased DNA fragmentation and decline in both antioxidant enzymes activity namely catalase (CAT) and superoxide dismutase (SOD) in granulosa cells of antral follicles. Moreover, there was found a significant negative correlation between the apoptosis incidence and the level of antioxidant enzymes activity, SOD (r = -0.73 p < 0.01) and CAT (r = -0.80 p < 0.01), in malathion treated ovarian antral follicles. Thus, highlighting the role of DNA fragmentation and declining antioxidant level as a possible mechanism underlying malathion induced reproductive toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1944-1954, 2016.

The reproductive life span of the organism mainly depends on follicular development that maintains the primordial follicle pool in the cohort of follicles within the ovary.The total count of primordial follicles decreases with age due to ovulation and follicular atresia. Follicular atresia, a process of ovarian follicles degradation, mainly occurs via apoptosis, but recent studies also favor autophagy existence. Autophagy

Cadmium (Cd) is a toxic heavy metal with no known biological functions in the human body. Due to a considerably long biological half-life and very low rate of excretion, accumulation of Cd in different body organs (eg, liver, kidney, and testes) over time is associated with perturbed functioning of these organs. Recent studies have shown the extreme sensitivity of the testes to Cd toxicity. In testes, Cd has been reported to induce oxidative stress, apoptosis of spermatogenic cells, reduction in androgen production and sperm functions. Moreover, Cd in combination with other environmental toxicants may be responsible for the declining fertility of males in both animals and humans. Pinpointing how Cd toxicity affects various testicular processes will be imperative for the development of preventative measures to promote fertility among males. Therefore, in the present review, we summarize the recent findings related to the Cd-induced oxidative toxicity, apoptotic toxicity, steroidogenic toxicity, and spermatotoxicity, along with their possible mechanisms in testicular tissue of different animal species. In addition, the utilization of various antioxidant compounds, medicinal plants and other compounds for the management of Cd toxicity in testes is discussed.