Anna Sellitti

Nonylphenol effects on the HPA axis of the bioindicator vertebrate, Podarcis sicula lizard

Nonylphenol (NP) is an endocrine disruptor widely distributed in the environment. It accumulates in the lipids of living organisms and enters the human food chain. The main source of human exposure is expected to be food, drinking water and foodstuff contaminated through leaching from packaging or pesticide formulation applications. NP acts as an estrogenic compound and it is able to mimic the action of estradiol 17β (E2) by binding to the estrogen receptor (ER). The aim of the present study was to investigate the NP effects on the hypothalamic-pituitary-adrenal gland (HPA) axis of the bioindicator Podarcis sicula lizard. A time-dependent stimulation of the HPA axis and variations of both catecholamine plasma levels were showed. Moreover, NP effects on adrenal gland morphology were evaluated by light and transmission electron microscopy. Clear morphological signs of adrenal gland stimulation such as an increase of steroidogenic cord diameter and vascularization, a strong escalation of adrenaline cell number and a decrease of noradrenaline cells were observed. The notably elevated levels of adrenal hormones suggested a permanent turning on of hypothalamic corticotropin releasing factor (CRF) secretion together with a lack of the negative feedback of HPA axis, perturbing systemic responses of the organism. Our data may help to predict the biological alterations induced by NP and to extend its impact upon adrenal function.

Effects of 4‐nonylphenol on proliferation of AGS gastric cells

Objectives:  Nonylphenol (NP) is present ubiquitously in both aquatic and terrestrial environments. This compound is considered an important endocrine disruptor and its toxic/oestrogenic activity has been investigated in a number of in vitro and in vivo studies. Human exposure to NP may occur by cutaneous absorption, ingestion of contaminated food or water and inhalation. Moreover, while the cytotoxic effects of NP are known and studied, its effects on cell death and related mechanisms are not known. Our group decided to investigate NP effects on a gastric epithelial cell line (AGS), in particular NP effects on AGS cell cycle and apoptosis.

Distribution and molecular evolution of the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptors in the lizard Podarcis sicula (Squamata, Lacertidae).

The presence of the pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptors PAC1, VPAC1, and VPAC2 was studied in the lizard Podarcis sicula gastrointestinal and respiratory tissues. The expression and distribution of this neuropeptide was investigated using RT-PCR, immunohistochemistry, and in situ hybridization techniques. RT-PCR showed that several tissues of this reptile synthesize an mRNA encoding for PACAP. Performing in situ hybridization and immunohistochemistry, we found a wide distribution of PACAP and its mRNA in intestine, stomach, liver, and lung. PACAP receptors possess a specific distribution in both gastrointestinal and respiratory system. Further, we analyzed the conservation of PACAP amino acid sequence demonstrating that this peptide in the lizard is very similar to that of other vertebrates. Our findings suggest that also in reptiles an effective PACAP system is present and that it could be implicated in some essential physiological functions as a result of its high conservation amongst vertebrates.

Thyroid Hormones as Potential Early Biomarkers of Exposure to Nonylphenol in Adult Male Lizard (Podarcis sicula)~!2009-10-05~!2010-02-25~!2010-05-17~!

The thyroid has been shown to be a target organ of environmental chemicals, specifically endocrine disrupting contaminants. Reptiles are particularly suitable as contaminant biomonitors, due to their persistence in a variety of habitats, wide geographic distribution, longevity, and, in many cases, site fidelity. Nonylphenol, an estrogenic-like compound, can induce vitellogenin synthesis in males and immature reptilian species, but little is known about its effects on thyroid hormones balance. The present study evaluated the potential effects of an acute exposure to nonylphenol (i.p. injected) on the thyroid of the lizard Podarcis sicula. Nonylphenol induced a significant decrease of T4 and T3 plasma levels, in agreement with the decrease of the epithelial cell height; the nuclei of the thyroid cells were small and elongated, with dense chromatin and a greatly reduced cytoplasm. The colloid was retracted with few reabsorption vacuoles. Moreover, nonylphenol administration significantly inhibited plasma thyroid-stimulating hormone levels, thereby altering the thyroid function. This study highlights how the structural and functional disruption of the thyroid gland in non-target organisms as the lizard might also have an environmental aetiology. In conclusion, nonylphenol was suspected to inhibit the thyroid hormones balance, suggesting the thyroid should be included among the other endocrine glands, susceptible to endocrine

A Preliminary Study of Cadmium Effects on the Adrenal Gland of the Lizard Podarcis sicula~!2009-11-25~!2010-03-23~!2010-05-14~!

Cadmium (Cd) is a heavy metal that can act as endocrine disruptor. Cadmium has the property to accumulate in several organs after entering the body and it principally accumulates in the adrenal glands. Although the uptake mechanisms for the cellular accumulation of Cd are unknown, the most common hypothesis states that Cd uptake involves competition with essential elements such as Ca or Zn for specific transport systems. Cd induces several effects such as cell death, carcinogenesis and disruption of neurotransmitter and hormone action. Particularly, cadmium is able to alter adrenocortical function inducing an impaired capacity to secrete cortisol by steroidogenic cells of the adrenocortical tissues and stimulating catecholamine secretion. In the present paper, we investigated the effects of cadmium exposure on the adrenal gland morphology of the lizard Podarcis sicula. For this purpose, we performed two different treatments in order to investigate cadmium effects after both acute and chronic treatments. We have demonstrated that cadmium has toxic effects on the lizard Podarcis sicula. Specifically, cadmium induces, in a time-dependent manner, steroidogenic cord hyperplasia, disorganization of steroidogenic parenchyma until necrotic degeneration that in turn evokes macrophage infiltration.

Effect of nonylphenol on gastric epithelial cells

Nonylphenol (NP) is an ubiquitous compound present in both aquatic and terrestrial environments besides aerial environment. It is considered an important endocrine disruptor as its toxic and estrogenic activity is well-known. Because of its large use in industrial and agriculture products, large amounts of this compound are released in the environment. Studies aimed at evaluating ways and exposure modalities of the human population to NP have demonstrated that it may mainly occur through feeding. Moreover while NP cytotoxicity is well known and studied, its effects on cell death and related mechanisms are not fully understood. Based on this background, we investigated the effects of NP on the human gastric cancer-derived cell line (AGS). In particular, this study focused on NP ability to regulate cell cycle and to induce apoptosis in AGS cells. The expression levels of several key regulatory apoptotic proteins such as p53, caspases 8, 9, and 3 were evaluated. In addition, the expression of p21,a crucial cell cycle regulator, was also monitored. Our results show that NP is able to induce growth inhibition and apoptosis in AGS in a concentration-and time-dependent manner. In particular, apoptosis occurs through activation of annexin V and a dose-dependent modulation of procaspase 3. The lack of modulation of caspase 9 ruled out the possibility of mitochondrial apoptotic pathway activation. Therefore NP induces apoptosis through caspase 8 activation. In addition, NP-induced apoptosis in AGS is p53-dependent, which peaks 6h after NP treatment.