Hormonally mediated effects of artificial light at night on behavior and fitness: linking endocrine mechanisms with function.

Alternation between day and night is a predictable environmental fluctuation that organisms use to time their activities. Since the invention of artificial lighting, this predictability has been disrupted and continues to change in a unidirectional fashion with increasing urbanization. As hormones mediate individual responses to changing environments, endocrine systems might be one of the first systems affected, as well as being the first line of defense to ameliorate any negative health impacts. In this Review, we first highlight how light can influence endocrine function in vertebrates. We then focus on four endocrine axes that might be affected by artificial light at night (ALAN): pineal, reproductive, adrenal and thyroid. Throughout, we highlight key findings, rather than performing an exhaustive review, in order to emphasize knowledge gaps that are hindering progress on proposing impactful and concrete plans to ameliorate the negative effects of ALAN. We discuss these findings with respect to impacts on human and animal health, with a focus on the consequences of anthropogenic modification of the night-time environment for non-human organisms. Lastly, we stress the need for the integration of field and lab experiments as well as the need for long-term integrative eco-physiological studies in the rapidly expanding field of light pollution.

Comparison of UV photolysis, nanofiltration, and their combination to remove hormones from a drinking water source and reduce endocrine disrupting activity.

A sequential water treatment combining low pressure ultraviolet direct photolysis with nanofiltration was evaluated to remove hormones from water, reduce endocrine disrupting activity, and overcome the drawbacks associated with the individual processes (production of a nanofiltration-concentrated retentate and formation of toxic by-products). 17ß-Estradiol, 17α-ethinylestradiol, estrone, estriol, and progesterone were spiked into a real water sample collected after the sedimentation process of a drinking water treatment plant. Even though the nanofiltration process alone showed similar results to the combined treatment in terms of the water quality produced, the combined treatment offered advantage in terms of the load of the retentate and decrease in the endocrine-disrupting activity of the samples. Moreover, the photolysis by-products produced, with higher endocrine disrupting activity than the parent compounds, were effectively retained by the membrane. The combination of direct LP/UV photolysis with nanofiltration is promising for a drinking water utility that needs to cope with sudden punctual discharges or deterioration of the water quality and wants to decrease the levels of chemicals in the nanofiltration retentate.

Methoprene photolytic compounds disrupt zebrafish development, producing phenocopies of mutants in the sonic hedgehog signaling pathway.

Environmental chemicals have been proposed to impact endocrine or retinoid pathways, causing developmental abnormalities in humans and other vertebrates. Presented evidence shows that exposure of zebrafish embryos to sunlight-induced photolytic products of the pesticide methoprene results in developmental defects in the head, heart, pectoral fins, and somites, and in spinal motor and optic nerve axons. Exposed embryos are phenocopies of zebrafish you-type mutants and, as in the mutant sonic-you, show underexpression of the signaling protein sonic hedgehog. Reduced expression of sonic hedgehog is also displayed in embryos treated with the retinoic acid synthesis inhibitor citral. This study identifies citral-related compounds as embryonic signaling disruptors of potential environmental concern.

[The reaction of the systems of hormonal mediator regulation to a weak geomagnetic field against a background of ionizing radiation exposure]. / Reaktsiia sistem gormonal'no-mediatornoi reguliatsii na gipogeomagnitnoe pole na fone vozdeistviia ioniziruiushchego izlucheniia.

Guinea pigs were subjected for 30 minutes to geomagnetic field of ten times decreased induction. The increase of epinephrine and histamine level in blood was observed. The decrease of histamine and serotonin concentration as well as normalization of epinephrine level were found when the influence of weakened geomagnetic field was stopped. Preliminary 2 Gy X-radiation resulted in the suppressed response of the organism to the weak geomagnetic field.

[The interaction of the thyroid-adrenal system with testicular function in mice subjected to gamma irradiation]. / Vzaimodeistvie tireoid-adrenalovoi sistemy s testikuliarnoi funktsiei u myshei, podvergnutykh gamma-oblucheniiu.

Single whole-body gamma-irradiation of BALB/c mice at a dose of 6.0 Gy results in an immediate response of the hypothalamus and hypophysis system: an increased generation of gonadotropin, adrenocorticotropin, and thyreotropin. The response of other organs manifests itself in an increase in testosterone, corticosterone and thyroxine in the organism. The above disturbances result in depression of the testicular activity and in fertility. The deficiency of testosterone is partly compensated by the enhancement of the adrenal secretion of adrogens.

[The hormonal status and carbohydrate-energy metabolism of rats after the long-term action of low doses of ionizing radiation and heat]. / Gormonal'nyi status i uglevodno-énergeticheskii obmen u krys posle dlitel'nogo deistviia malykh doz ioniziruiushchego izlucheniia i tepla.

Hormonal status (blood content of triiodothyronine, thyroxin, insulin, 11-hydroxycorticosteroids), dehydration in the Krebs cycle, and activity of the first enzyme in the pentose-phosphate cycle, glucose-6-phosphate dehydrogenase, in the brain and myocardium of white rats were studied at different time periods after separate and combined prolonged exposure to radiation in relatively small doses and heat. It was found that combination of ionizing radiation and heat led to hypofunction of the endocrine glands and inhibition of dehydration processes in the Krebs Cycle.

[The potential fertility, embryonic development and hormonal status of rats selected for their estrous cycle reaction to constant illumination]. / Potentsial'naia plodovitost', émbrional'noe razvitie i gormonal'nyi status krys, selektsionirovannykh po reaktsii éstral'nogo tsikla na postoiannoe osveshchenie.

Illumination responsiveness (IR) is studied by selection experiments with outbred Wistar rats. Under selection is estrous cycles under permanent illumination (PI) condition, changes in hormonal status, potential fertility, and embryonic developments ats different stages are registered and compared with control. Results indicate significant changes in endocrine regulatory system in the lines exposed to PI. Functional potentiality of reproductive system gets more weak as a result of this selection, which leads to decreasing in number of ovulations, defective development of placenta, less embryo weights, higher embryo mortality. The opposite conditions are observed in rats undergone selection of stability of estrous cycle. It is concluded that the above selection reveals formation of regulatory mechanisms of reproduction on different genetical physiological bases.

[The hormonal functions regulating carbohydrate metabolism in participants in the cleanup of the sequelae of the accident at the Chernobyl Atomic Electric Power Station with a neurocirculatory dystonia syndrome]. / Gormonal'nye funktsii, reguliruiushchie uglevodnyi obmen, u uchastikov likvidatsii posledstvii avarii na Chernobyl'skoi AES s sindromom neirotsirkuliatornoi distonii.

Radioimmunoassay revealed in participants of Chernobyl disaster sequelae preclinical changes of some hormonal functions: moderate increase of the basal concentration of blood insulin, somatotropin, C-peptide against the background of persistent hypercortisolemia. Increase of the level of "hyperglycemic" hormones (cortisol, somatotropin, C-peptide) is explained by adaptative and compensatory reactions of the body in response to lesioning effects of ionizing radiation and other negative factors of the Chernobyl accident. Relative hyperinsulinemia is, apparently, compensating the total hyperglycemic effect of these hormones leading to stabilization of the blood sugar level.

[The long-term sequelae of the effect of incorporated radioactive iodine on the endocrine system in an endemic locality-]. / Viddaleni naslidky vplyvu inkorporovannoho radioaktyvnoho iodu na endokrynnu systemu v umovakh endemichnoï mistsevosti.

25-30 years after the 131J therapeutic dose intake the function of the thyroid gland was found to get impaired in 18% of those irradiated, with the diabetes mellitus incidence rate tending to be on the increase almost two-fold. 131J did not have apparent suppressive action on sexual glands and adrenals. In those persons having taken 131J, frequency of the thyroid gland neoplasia gets increased almost 6-fold as compared to general population.

[The hormone level of the blood plasma in neurodermatitis patients and its dynamics during the performance of nondrug pathogenetic therapy]. / Soderzhanie gormonov v plazme krovi bol'nykh neirodermitom i ikh dinamika v protsesse provedeniia nemedikamentoznoi patogeneticheskoi terapii.

Concentrations of hormones of the hypophysis, thyroid gland and adrenal cortex were measured in blood plasma of those patients presenting with neurodermatitis. A statistically significant reduction in the blood content of thyroid-stimulating hormone (TSH) and hydrocortisone and rise in aldosterone, adrenocorticotrophic hormone (ACTH), triiodothyronine and thyroxin were revealed in this patient population. Combined non-drug therapy treatments involving endovascular helium-neon laser therapy and EHF electromagnetic radiation resulted in improvement in more than half of the measurements done: blood levels of TSH and hydrocortisone got increased while those of ACTH, thyroxin and aldosterone decreased, which fact correlated with the positive clinical picture of the condition in question.

[The correction of the immunohormonal disorders in patients with hyperplastic processes in the endometrium]. / Korrektsiia immunogormonal'nykh narushenii u bol'nykh s giperplasticheskimi protsessami v éndometrii.

Effects were studied of extremely high-frequency electromagnetic radiation (EHF ER) on indices for the immune and endocrine systems in 48 patients with hyperplastic processes in the endometrium. It is ascertain that along with the established normalization of parameters characterizing the above systems there occurs a return of correlations back to normal, which fact permits using EHF ER as an immunocorrective factor.

[The immunological and hormonal effects of combined exposure to a bitemporal ultrahigh-frequency electrical field and to decimeter waves at different sites]. / Immunologicheskie i gormonal'nye éffekty sochetannogo vozdeistviia élektricheskogo polia ul'travysokoi chastoty bitemporal'no i detsimetrovykh voln razlichnoi lokalizatsii.

Bitemporal UHF electric field is shown to enhance glucocorticoid adrenal function unlike inhibition of the thyroid function suppressing a primary immune response (PIR) in the productive phase. The combined exposure to bitemporal UHF electric field and decimeter waves of the adrenals doubles glucocorticoid synthesis abolishing the inhibitory action of the UHF therapy on thyroid function resultant in much more suppressed PIR. Both modalities inhibit thymic production. Decimeter waves alone are less effective. The exposure of the thyroid to decimeter waves initiated PIR by 2.5-fold activation of medullar lymphocytes and by a 80% increase in the thymic function. No response was achieved in combined action on the thyroid of the electric field and decimeter waves.

[The effect of radon on the hormonal regulation of carbohydrate metabolism]. / Vliianie radona na gormonal'nuiu reguliatsiiu uglevodnogo obmena.

Wistar rat experiments provided evidence for marked inhibition of early insulin secretion after a single dose of radon water (radon concentration 200 nCi/1). Hepatocytes and activity of transaminase remained unchanged. Miners in long contact with radon in mines (radon concentration in the air of mines 1.5 nCi/1) develop long-term adaptation of the hormonal systems associated with hyperadaptosis in the system of hormonal regulation of glycohomeostasis.

[The dynamics of the immunobiological effects in transcerebral microwave exposures]. / Dinamika immunobiologicheskikh éffektov pri transtserebral'nykh mikrovolnovykh vozdeistviiakh.

The trend in immunobiological responses to transcerebral action of decimeter microwaves was studied in intact rabbits. Transcerebral microwaves (120 mW/cm2) can alter functional activity of certain links of endocrine system due to possible activation of hypothalamus and hypophysis exposed to microwave electromagnetic field. Such exposure given in courses at early stages leads to an increase in the number of antibody-forming cells in the spleen, whereas total number of splenocytes is on the decrease.

[The immune and hormonal effects of the local action of microwaves of different intensities]. / Immunnye i gormonal'nye éffekty lokal'nogo vozdeistviia mikrovoln razlichnoi intensivnosti.

The trend in immune and hormonal parameters in thyroid, adrenal and transcerebral exposure to microwaves with intensity of 120, 240 and 480 mW/cm2 was studied in rabbits. The thyroid exposure to 120 and 240 mW/cm2 microwaves lead to immunostimulation, while adrenal and transcerebral one induced immunosuppression. The exposure to 240 mW/cm2 and 480 mW/cm2 microwaves resulted in damage to the tissues in 56 and 100% of the animals, respectively. The latter irradiation appeared lethal for 25% of the rabbits. 120 mW/cm2 MV proved safe as there were no signs of edema and necrosis seen with more intensive microwaves. The authors suggest to employ microwaves of 120 mW/cm2 intensity for endocrine glands irradiation to produce an immunomodulating effect.

[A comparative analysis of the biological action of microwaves and laser radiation]. / Sravnitel'nyi analiz biologicheskogo deistviia mikrovoln i lazernogo izlucheniia.

The author gives a comparative analysis of the mechanism of biological action of microwaves and laser radiation in the range of molecular to body level. Similar and different characteristics of these factors are specified.

[The effect of decimeter waves on the metabolism of the myocardium and its hormonal regulation in rabbits with experimental ischemia]. / Vliianie detsimetrovykh voln na metabolizm miokarda i ego gormonal'nuiu reguliatsiiu u krolikov s éksperimental'noi ishemiei.

Biochemical and morphometric methods were employed to study the effect of decimetric waves (460 MHz, 10 and 120 mW/cm2) in cardiac and thyroid exposure on oxygen metabolism, myocardial microcirculation and contractility, thyroid and adrenal hormonal activity, kallikrein-kinin system activity in rabbits with experimental myocardial ischemia. Hypoxia discontinued in all the treatment regimens, but the exposure of the heart (field density 10 mW/sm2) had the additional effect on lipid peroxidation which reduced in the serum and normalized in the myocardium, on myocardial contractility, kallikrein-kinin system and on the adrenal and thyroid hormones.

[A clinical and experimental analysis of the effects of laser therapy]. / Kliniko-éksperimental'nyi analiz éffektov lazerterapii.

Thymus area was exposed to laser radiation in 180 Wistar male rats. Intact animals experienced a stress response to a single laser procedure (a rise in the levels of hydrocortisone, a fall in those of insulin, triiodothyronine and thyroxine). Longer exposure to laser radiation caused a break of the hydrocortisone mechanism. Similar effects were seen in the course exposure. The immune system was unchanged. In adjuvant arthritis laser radiation induced similar hormonal shifts and additional suppression of immunity. In 82 children with active juvenile rheumatoid arthritis laser therapy produced an insignificant effect, while in adults with moderate rheumatoid arthritis the response was good.