Perinatal exposure to Aroclor 1254 disrupts thyrotropin-releasing hormone mRNA expression in the paraventricular nucleus of male and female rats

Polychlorinated biphenyls (PCBs) are industrial pollutants that act as endocrine disruptors and alter thyroid function. However, it is still unclear whether PCBs can affect hypothalamic thyrotropin releasing hormone (Trh) mRNA expression through TH signaling disruption. As salt-loading dehydration induces tertiary hypothyroidism in the hypothalamic parvocellular paraventricular nuclei (paPVN), and perinatal exposure to Aroclor 1254 (A1254) disrupts the hydric balance in rats, we hypothesized that TRH synthesis could be altered during dehydration in TRH neurons that control the hypothalamic–pituitary–thyroid (HPT) axis activity in rats perinatally exposed to A1254. We examined Trh mRNA expression in the paPVN and the response to salt-loading dehydration (hyperosmotic (hyper) stress) in the progeny of Wistar pregnant rats receiving 0 mg/kg BW (control) or 30 mg/kg BW A1254 daily from gestational days 10–19. Three-month-old offspring were subjected to normosmotic or hyper conditions and Trh mRNA, glucocorticoid receptor (GR) mRNA expression were measured in the PVN by RT-PCR. TRH mRNA and TRH+ neurons were measured in the paPVN by fluorescent in situ hybridization (FISH). As expected, Trh mRNA levels were decreased in the paPVN of male and female rats in the hyper group. Basal Trh mRNA expression and serum TSH were decreased in male rats in the A1254 group. Notably, Trh mRNA levels were further decreased in the paPVN of male and female A1254 + hyper rats, in which the GR mRNA expression was significantly decreased. These results support the hypothesis that perinatal exposure to A1254 results in inadequate adaptive response of the HPT axis in adulthood and contributes to dysregulation of the HPT axis response to salt-loading dehydration

Primary explants of the postnatal thymus allow the expansion of clonogenic thymic epithelial cells that constitute thymospheres

Abstract Background Thymic epithelial cells (TECs) are responsible for shaping the repertoires of T cells, where their postnatal regeneration depends on a subset of clonogenic TECs. Despite the implications for regenerative medicine, their cultivation and expansion remain challenging. Primary explant cell culture is a technique that allows the seeding and expansion of difficult-to-culture cells. Here, we report a reliable and simple culture system to obtain functional TECs and thymic interstitial cells (TICs). Methods To establish primary thymic explants, we harvested 1 mm cleaned fragments of thymus from 5-week-old C57/BL6 mice. Tissue fragments of a complete thymic lobe were placed in the center of a Petri dish with 1 mL of DMEM/F-12 medium supplemented with 20% fetal bovine serum (FBS) and 1% penicillin‒streptomycin. To compare, thymic explants were also cultivated by using serum-free DMEM/F-12 medium supplemented with 10% KnockOut™. Results We obtained high numbers of functional clonogenic TECs and TICs from primary thymic explants cultivated with DMEM/F-12 with 20% FBS. These cells exhibited a highly proliferative and migration profile and were able to constitute thymospheres. Furthermore, all the subtypes of medullary TECs were identified in this system. They express functional markers to shape T-cell and type 2 innate lymphoid cells repertoires, such as Aire, IL25, CCL21 and CD80. Finally, we also found that ≥ 70% of lineage negative TICs expressed high amounts of Aire and IL25. Conclusion Thymic explants are an efficient method to obtain functional clonogenic TECs, all mTEC subsets and different TICs Aire+IL25+ with high regenerative capacity

The impact of conservation on the status of the world's vertebrates

Using data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world's vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to extinction each year. However, this overall pattern conceals the impact of conservation successes, and we show that the rate of deterioration would have been at least one-fifth again as much in the absence of these. Nonetheless, current conservation efforts remain insufficient to offset the main drivers of biodiversity loss in these groups: agricultural expansion, logging, overexploitation, and invasive alien species