Neuroendocrine Disruption: More Than Hormones are Upset

Abstract

Only a small proportion of the published research on endocrine-disrupting chemicals (EDC) directly examined effects on neuroendocrine processes. There is an expanding body of evidence that anthropogenic chemicals exert effects on neuroendocrine systems and that these changes might impact peripheral organ systems and physiological processes. Neuroendocrine disruption extends the concept of endocrine disruption to include the full breadth of integrative physiology (i.e., more than hormones are upset). Pollutants may also disrupt numerous other neurochemical pathways to affect an animal's capacity to reproduce, develop and grow, or deal with stress and other challenges. Several examples are presented in this review, from both vertebrates and invertebrates, illustrating that diverse environmental pollutants including pharmaceuticals, organochlorine pesticides, and industrial contaminants have the potential to disrupt neuroendocrine control mechanisms. While most investigations on EDC are carried out with vertebrate models, an attempt is also made to highlight the importance of research on invertebrate neuroendocrine disruption. The neurophysiology of many invertebrates is well described and many of their neurotransmitters are similar or identical to those in vertebrates; therefore, lessons learned from one group of organisms may help us understand potential adverse effects in others. This review argues for the adoption of systems biology and integrative physiology to address the effects of EDC. Effects of pulp and paper mill effluents on fish reproduction are a good example of where relatively narrow hypothesis testing strategies (e.g., whether or not pollutants are sex steroid mimics) have only partially solved a major problem in environmental biology. It is clear that a global, integrative physiological approach, including improved understanding of neuroendocrine control mechanisms, is warranted to fully understand the impacts of pulp and paper mill effluents. Neuroendocrine disruptors are defined as pollutants in the environment that are capable of acting as agonists/antagonists or modulators of the synthesis and/or metabolism of neuropeptides, neurotransmitters, or neurohormones, which subsequently alter diverse physiological, behavioral, or hormonal processes to affect an animal's capacity to reproduce, develop and grow, or deal with stress and other challenges. By adopting a definition of neuroendocrine disruption that encompasses both direct physiological targets and their indirect downstream effects, from the level of the individual to the ecosystem, a more comprehensive picture of the consequences of environmentally relevant EDC exposure may emerge.

Pond Snail Reproduction as Model in the Environmental Risk Assessment: Reality and Doubts

“…It is concluded that endocrine disruption is not considered a toxicological end point per se but a functional change that may lead to adverse effects in both non-target and target organisms, as well. EDCs act as agonist or antagonists at multiple sites via complex mechanisms of action including: receptor-mediated mechanisms, synthesis and/or metabolism of hormones, neuropeptides and neurotransmitters, as well as transport pathways [32].…”

The Neuroendocrine and Neurodevelopmental Effects of Endocrine Disrupting Chemicals

“…Turkiye Klinikleri J Neur 2018;13(1): [7][8][9][10][11][12][13][14][15][16][17][18][19] lar, DEHP maruziyetine erkek ve dişilerin yaş ve doz-yanıt eğrisi açısından farklı yanıtlar verdiğini göstermektedir. 19 Hipotalamustaki anteroventral periventrikü-ler çekirdek (AVPV) ve cinsel dimorfik çekirdek-mediyal preoptik alan [sexually dimorphic nucleus of the preoptic area (SDN-POA)] cinsiyete özgü üreme fizyolojisi ve davranışlarda rol oynamakta ve her iki bölge de östradiole bağlı olarak cinsiyete bağlı gelişim göstermektedir.…”

“…Turkiye Klinikleri J Neur 2018;13(1): [7][8][9][10][11][12][13][14][15][16][17][18][19] BPA gibi EBK'lere maruziyet, ayrıca morfin ve amfetamin gibi maddelerin limbik sistemde indük-lediği yüksek hareketlilik (hiperlokomosyon) ve ödül etkisini G-protein aktivasyonu yoluyla önemli ölçüde artırmaktadır. Narita ve ark.nın yaptığı bir çalışmada, implantasyon (GD0-7), organogenez (GD7-14), parturisyon (GD14-20) ve laktasyon (PND1-21) olmak üzere dört farklı dönemde 2 mg/kg BPA maruziyetinin etkileri araştırılmıştır.…”

Impacts of Endocrine Disrupting Chemicals on Reproduction in Wildlife

“…The oldest papers related to reproduction dated back to 1995, thus demonstrating how much this particular fi eld has advanced in less than two decades. Within this short review it is impossible to cite all of the available work in this taxa, so we will summarise by focusing on major reviews; 70 in total, including recent ones by McNair et al ( 2012 ), Soffker and Tyler ( 2012 ) and Waye and Trudeau ( 2011 ). The European Environment Agency report ( 2012 ) also provides a useful and succinct summary of this area.…”