Abstract
Evidence demonstrates the bidirectional communication and regulation between the neuroendocrine and immune systems. Thyroid hormones play key roles in nervous system development and can exert influence on various immune cells contributing to pathophysiological conditions. Octyl methoxycinnamate (OMC) is one of the most commonly used UV filters, and in vitro and in vivo studies have found thyroid disrupting effects. The present study assessed whether OMC administration in mice dams during the lactational period can cause thyroid disruption and generate immunologic alterations in the offspring. Indirect exposure to the OMC (1,000 mg/kg) in the lactational period affected neurodevelopment parameters, such as delayed eye-opening and weight gain in mice of both sexes, and these alterations are corroborated by the decrease in the T4 levels present in the pups' blood. No significant changes were observed in the thymus of these pups, but the number of lymphocytes increased in the spleen of the animals exposed to OMC, similar to the animals treated with propyl-thiouracil (PTU), a well-known thyroid disruptor. OMC modulated the percentage of leukocyte populations in peripheral blood, and the number of circulating polymorphonuclear cells increased two-fold. In vitro, OMC exhibited an inhibitory effect on splenocyte proliferation and IL-2 production induced by anti-CD3 antibody; however, this effect was reversed with the addition of T4 in the cell culture. In summary, the results of the present study demonstrate the influence of OMC on thyroid dysregulation and its impact on the modulation of the immune system in mice pups.
Highlights
The octyl methoxycinnamate (OMC), known as octinoxate, is probably the organic ultraviolet (UV) filter used most by the cosmetic industry
Lactating pups fed by females exposed to 1,000 mg/Kg/day of Octyl methoxycinnamate (OMC) showed a significant reduction in weight gain and a delay in eye opening compared to the vehicle group (Figures 1A,B and Table 1)
These data were in agreement with results obtained by our group in rats, where the direct exposition to OMC interfered in diverse developmental parameters in pups, wich were linked to a decrease of thyroid activity
Summary
The octyl methoxycinnamate (OMC), known as octinoxate, is probably the organic ultraviolet (UV) filter used most by the cosmetic industry. OMC was reported to induce acute toxicities, and a large number of studies, both in vivo and in vitro, found multiple endocrine disrupting effects in the estrogen receptor (ER), androgen receptor (AR), progesterone receptor (PR), and hypothalamus-pituitary-thyroid (HPT) axis [8,9,10]. Several UV filters have already been cataloged and reported as a HPT function deregulators, especially when exposed to during the early stages of development [11]. These actions can directly affect the gland and/or the corresponding regulatory centers, such as the hypothalamus and the pituitary, affecting the levels of thyrotropin releasing hormone (TRH) and/or thyroidstimulating hormone (TSH), which are directly related to the synthesis of thyroid hormones. Most studies have focused on the estrogenic and anti-androgenic effects of OMC in wild and lab animals [12,13,14]; only a few studies focused on the influence of OMC upon the HPT function [15,16,17]
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