Plasma T3 Research Articles

Effect of Laparoscopic Ovarian Drilling on Anti-Müllerian Hormone Level among Women with Polycystic Ovary Syndrome : A Retrospective Study

Background: Thyroid dysfunction is associated with increased cardiovascular morbidity and mortality. Hyperthyroidism increases the susceptibility of the heart to ischemia reperfusion injury. Moreover, myocardial ischemia can be further worsened by increased cardiac workload and oxygen demand elicited by the excess thyroid hormones. Objectives: Investigating the cardiac dysfunction induced by ischemia-reperfusion (IR) in rats exposed to excess thyroid hormones and role of somatostatin analogue against ischemia/reperfusion injury in hyperthyroid rats. Patients and Methods: This study was performed on 24 adult male albino rats of a local strain weighing 140-200 g, allocated into three equal groups: Group I (Control IR group): Euthyroid control group exposed to ischemia-reperfusion. Hearts of this group were isolated and perfused in a Langendorff apparatus. Isolated hearts were subjected to 15 min of stabilization, 20 min of zero-flow global ischemia and 30 min of reperfusion. Group II (Hyperthyroid IR group) were subjected to the same protocol of ischemia reperfusion. Group III (Hyperthyroid IR-OCT group): Hyperthyroid rats were supplemented with the somatostatin analogue, octreotide (OCT), 35 µg/kg subcutaneously, 20 minutes before sacrifice, followed by in-vitro study of cardiac responses to ischemia reperfusion. Blood samples were collected for measurement of plasma free T3, T4 and TSH. Coronary efflux lactate dehydrogenase levels were measured. Also, cardiac tissue malondialdehyde (MDA) levels and tumor necrosis factor alpha (TNF-α) levels were estimated. Results: Hyperthyroid (IR) rats revealed significant elevation in plasma free T3 and T4 with concomitant decrease in TSH levels. A significant reduction in final BW and BW gain were observed with higher absolute weights of left ventricle (LV) and cardiac index compared to the euthyroid controls. Systolic blood pressure (SBP) and mean arterial pressure (MAP) significantly elevated in non-treated hyperthyroid rats with a significant increase in their baseline chronotropic and inotropic activity compared to euthyroid control rats. But after ischemia those rats exhibited significantly higher degree of bradycardia (∆HR) and % change in heart rate (HR) compared to control rats. Moreover, significantly deteriorated post-ischemic recovery of inotropic parameters and significantly higher ∆ changes of these parameters were observed compared to euthyroid controls. These changes were accompanied by significant elevation in coronary efflux LDH levels and both cardiac tissue MDA and TNFα. Meanwhile, octreotide administration to hyperthyroid rats showed improvement of their baseline chronotropic and inotropic parameters as evidenced by the significantly reduced degree of bradycardia as well as significantly lower ∆ change of PT and PT/LV parameters compared to non-treated hyperthyroid rats. Such findings could be ascribed partly to the reduction of oxidative and inflammatory responses to IR as determined by the significantly decreased cardiac tissue MDA and TNFα respectively. Conclusion: Hyperthyroid hearts are less tolerant to ischemia/reperfusion injury with higher susceptibility to oxidative stress as well as overproduction of pro-inflammatory mediators. Thus, pharmacological targets that defend oxidative challenge and confer anti-inflammatory properties, namely octreotide (somatotstatin analogue) are considered to have potential therapeutic effect and may protect against myocardial ischemic damage in hyperthyroidism.

Summer season induced rhythmic alterations in metabolic activities to adapt to heat stress in three indigenous (Osmanabadi, Malabari and Salem Black) goat breeds

A study was conducted to assess the adaptive capability of three indigenous goat breeds to heat stress. Thirty six 10 months to one-year-old female goats of Osmanabadi, Malabari and Salem Black breeds were randomly divided into six groups, OC (n = 6; Osmanabadi control), OHS (n = 6; Osmanabadi heat stress), MC (n = 6; Malabari control), MHS (n = 6; Malabari heat stress), SBC (n = 6; Salem Black control) and SBHS (n = 6; Salem Black heat stress). Among the metabolic activity controlling hormones, the breed factor significantly (P < 0.05) influenced only plasma triiodothyronine (T3). However, heat stress significantly (P < 0.05) decreased thyroid stimulating hormone (TSH) in both MHS and SHS groups while significantly (P < 0.05) decreased the plasma T3 in MHS. The rumen metabolites such as acetate, propionate, butyrate and total volatile fatty acids (TVFAs) showed significant (P < 0.05) variation for both breed and treatment effect. The Salem Black breed did not show any significant variation for most of the rumen metabolites as compared to both Osmanabadi and Malabari breeds for the heat stress treatment. The study indicated the importance of the metabolic alterations in indigenous goat breeds to cope to the seasonal rhythms. The results indicated that on comparative basis, Salem Black breed adapted better to the heat stress challenges.

Biological ability of Malpura rams to counter heat stress challenges and its consequences on production performance in a semi-arid tropical environment

A study was conducted to assess the biological ability of Malpura rams to counter heat stress challenges and its impact on the productive performance in a semi-arid tropical environment. The eighteen adult Malpura rams (average body weight 55.0 kg) were divided into two groups, GI (n = 9; Control) and GII (n = 9; heat stress). The study was conducted for a period of 60 days. The results showed that body weight, body condition score, heart girth and feed intake were significantly (p < 0.05) lower in GII as compared to GI rams. The physiological responses i.e. respiration rate, pulse rate, rectal temperature and sweating rate (body and scrotum) were significantly (p < 0.05) higher in rams exposed to heat stress. Among the endocrine parameters, plasma T3, T4 and testosterone concentrations were significantly (p < 0.05) lower in GII rams, while cortisol concentration was significantly (p < 0.05) higher in GII rams. In addition, heat stress significantly (p < 0.05) reduced semen volume, total sperm motility, sperm concentration and progressive sperm motility in GII rams. The results indicated that Malpura rams adapted to the heat stress condition, however, while doing so their production performances were compromised.

Physiological responses and performance of broiler chickens offered olive leaf extract under a hot humid tropical climate

This study was designed to determine the effects of olive leaf extract (OLE) supplementation in the drinking water on growth performance, hematological parameters, plasma triiodothyronine and malondialdeyde, superoxide dismutase, and rectal temperature of broiler chickens under a hot-humid tropical climate. Two hundred and forty Arbor acre broiler chickens were used for this experiment and were allotted to four treatments comprising four replicates of 15 birds each. The birds were offered OLE per liter of water at various levels (0, 5, 10, or 15 mL) in a completely randomized design. Rectal temperature (RT), hematological indices, weight, weight gains, feed consumed, feed conversion ratio, and plasma triiodothyronine (T3) were the parameters measured. The results obtained showed that the plasma T3 of the birds offered 15 mL OLE was higher (P < 0.05) than those of the birds in the other treatment groups. Significant differences (P < 0.05) were observed in the feed intake (DFI), total feed intake (TFI), final weight (FW), total weight gain (TWG), and feed conversion ratio (FCR) among treatments. The DFI, TFI, FW, TWG, and FCR of broilers offered 15 mL OLE were significantly (P < 0.05) better than those offered the 10 mL and 5 mL levels. It was concluded that inclusion of 15 mL of OLE enhanced the performance of broiler chickens during the hot dry season.

Accumulation of Cadmium and Antioxidant and Hormonal Responses in the Indian Major Carp Cirrhinus mrigala During Acute and Sublethal Exposure

Acute (24 h) and sublethal (35 days) effects of cadmium chloride (CdCl2) were examined in Cirrhinus mrigala using various endpoints (accumulation pattern, thyroid hormones (THs), and antioxidants). The mean concentrations of CdCl2 for 24 and 96 h were found to be 35.974 and 22.387 mg L−l, respectively. LC50 concentration of CdCl2 for 24 h (35.97 mg L−l) was used for the acute study. For the sublethal studies, fish were exposed to 3.59 mg L−1 (Treatment I) and 7.19 mg L−1 (Treatment II) corresponding to 1/10th and 1/5th of 24 h LC50 of the CdCl2. During acute exposure, higher accumulation of CdCl2 was noticed in the gill, liver, and kidney of C. mrigala, which is found in the order gill > liver > kidney tissues. Similarly, in sublethal treatments (Treatment I and II), a concentration and time-dependent increase of CdCl2 accumulation was noticed in the order of gill > liver > kidney. GSH, GST, and GPx activities were found to be relatively lower from the treated groups in both acute and sublethal treatments. However, LPO activity was significantly increased in CdCl2-treated fish C. mrigala. Further, plasma T3 reduction was more pronounced than T4 in acute study. During sublethal treatments, both T4 and T3 levels showed a continuous decrease as the exposure period extended. All the values in this study were statically significant (P < 0.01 and P < 0.05).

Genome-wide identification of thyroid hormone receptor targets in the remodeling intestine during Xenopus tropicalis metamorphosis

Thyroid hormone (T3) affects development and metabolism in vertebrates. We have been studying intestinal remodeling during T3-dependent Xenopus metamorphosis as a model for organ maturation and formation of adult organ-specific stem cells during vertebrate postembryonic development, a period characterized by high levels of plasma T3. T3 is believed to affect development by regulating target gene transcription through T3 receptors (TRs). While many T3 response genes have been identified in different animal species, few have been shown to be direct target genes in vivo, especially during development. Here we generated a set of genomic microarray chips covering about 8000 bp flanking the predicted transcription start sites in Xenopus tropicalis for genome wide identification of TR binding sites. By using the intestine of premetamorphic tadpoles treated with or without T3 and for chromatin immunoprecipitation assays with these chips, we determined the genome-wide binding of TR in the control and T3-treated tadpole intestine. We further validated TR binding in vivo and analyzed the regulation of selected genes. We thus identified 278 candidate direct TR target genes. We further provided evidence that these genes are regulated by T3 and likely involved in the T3-induced formation of adult intestinal stem cells during metamorphosis.

Thyroid function of steatitis-affected Mozambique tilapia Oreochromis mossambicus from a sub-tropical African reservoir.

Thyroid function and nutritional indicators were measured in obese, steatitis-affected Mozambique tilapia Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. Plasma thyroid hormones (especially T3) and thyroid follicle histomorphology revealed high levels of activity in every aspect of the thyroid cascade measured in fish from LR compared to a reference population of steatitis-free fish. Concurrent measurements of nutritional state including plasma lipids, liver lipid content and hepatocyte size showed that fish from LR had significant energy stores indicative of abundant nutritional intake. There were distinct sex and seasonal differences, with the highest plasma lipids and T3 levels observed in steatitis-affected females during spring and summer. Positive correlations were observed between plasma lipids (especially cholesterol) and T3 concentrations in fish from both populations, indicating a link between lipid metabolism and thyroid function. There was no direct evidence of thyroid disruption, but this cannot be ruled out until further research determines the factors that underlie the homeostatic shift leading to elevated plasma and liver lipids and T3 levels in steatitis-affected tilapia.

Effects of Combined Exposure to Chronic High-Fat Diet and Arsenic on Thyroid Function and Lipid Profile in Male Mouse.

The thyroid is one of the major endocrine glands that contribute to body and fat metabolism. The present study evaluated the effects of combined exposure to chronic high-fat diet (HFD) and arsenic on thyroid function and lipid profile. In this experimental study, 72 male Naval Medical Research Institute mice were divided into six groups and fed HFD or low-fat diet (LFD) while being exposed to 25 or 50ppm of arsenic in drinking water for 20weeks. After 24h of the last experimental day, blood samples were collected for hormonal and biochemical measurements. The data indicated that exposure to HFD alone increased the levels of triiodothyronine (T3), thyroid-stimulating hormone (TSH), leptin, lipid profile, reactive oxygen species (ROS), and malondialdehyde (MDA) and decreased the levels of high-density lipoprotein, albumin, adiponectin, and glutathione sulfhydryl reductase (GSH), whereas exposure to arsenic alone decreased the levels of T3 and GSH and increased the levels of TSH, leptin, ROS, MDA, and T4/T3 ratio compared to those in the control LFD group. Furthermore, concomitant administration of HFD and arsenic decreased the lipid profile and levels of T4, albumin, total protein, T3, and GSH and increased the levels of TSH, adiponectin, leptin, ROS, MDA, and T4/T3 ratio compared to those in the control LFD or HFD group. In conclusion, combined exposure to HFD and arsenic induced hypothyroidism via reduction of thyroid hormones and enhancement of plasma TSH and T3 uptake levels concomitant with hypolipidemia, hyperleptinemia, hyperadiponectinemia, induction of oxidative stress, and reduction of GSH levels.

Plasma proteins, hepatic enzymes, thyroid hormones and liver histopathology of Cyprinus carpio (Linnaeus, 1758) exposed to an oxadiazin pesticide, indoxacarb

Indoxacarb is a relatively new pesticide from oxadiazin class, which is used near carp ponds for agricultural purposes. Thus, the aim of this study was to determine indoxacarb effects on common carp (Cyprinus carpio). The fish were exposed to 0 (control), 0.75, 1.5 and 3 ppm of indoxacarb over 21 days and plasma biochemical characteristics and liver histopathology were examined. Exposure to indoxacarb induced fall in total protein after 21 days. Globulin increased after 7 days and then decreased after 14- and 21-day exposure. Plasma alanine transaminase and aspartate transaminase activities increased in 1.5 and 3 ppm treatments after 7-day exposure. Indoxacarb exposure significantly decreased plasma alkaline phosphatase after 7 days with no change at the second and third samplings. After 7 days, plasma T3 levels had no significant change; however, it decreased after 14 days in the 1.5 and 3 ppm treatments and also reduced after 21-day exposure to the 3 ppm treatment compared to the control group. Plasma T4 level only decreased significantly in the 3 ppm treatment compared to the control group after 21 days. Different histopathological symptoms such as necrosis, hyperaemia, sinusoidal space extension, pyknotic nuclei, leucocyte infiltration and melanomacrophage aggregates were observed after 21-day exposure to indoxacarb. The symptoms intensity was dependent on indoxacarb concentration. In conclusion, the present results show that indoxacarb exposure adversely affects common carp health and welfare, which consequently may induce serious problems in this species aquaculture.

Do migrant and resident species differ in the timing of increases in reproductive and thyroid hormone secretion and body mass? A case study in the comparison of pre-breeding physiological rhythms in the Eurasian Skylark and Asian Short-toed Lark

BackgroundPhysiological preparation for reproduction in small passerines involves the increased secretion of reproductive hormones, elevation of the metabolic rate and energy storage, all of which are essential for reproduction. However, it is unclear whether the timing of the physiological processes involved is the same in resident and migrant species that breed in the same area. To answer this question, we compared temporal variation in the plasma concentration of luteinizing hormone (LH), testosterone (T), estradiol (E2), triiothyronine (T3) and body mass, between a migrant species, the Eurasian Skylark (Alauda arvensis) and a resident species, the Asian Short-toed Lark (Calandrella cheleensis), both of which breed in northeastern Inner Mongolia, China, during the 2014 and 2015 breeding seasons.MethodsTwenty adult Eurasian Skylarks and twenty Asian Short-toed Larks were captured on March 15, 2014 and 2015 and housed in out-door aviaries. Plasma LH, T (males), E2 (females), T3 and the body mass of each bird were measured every six days from March 25 to May 6.ResultsWith the exception of T, which peaked earlier in the Asian Short-toed Lark in 2014, plasma concentrations of LH, T, E2 andT3 of both species peaked at almost the same time. However, Asian Short-toed Larks attained peak body mass earlier than Eurasian Skylarks. Plasma T3 concentrations peaked 12 days earlier than plasma LH in both species. Generally, plasma LH, T, E2, T3 and body mass, peaked earlier in both species in 2014 than 2015.ConclusionsThe timing of pre-reproductive changes in the endocrine system and energy metabolism can be the same in migrant and resident species; however, residents may accumulate energy reserves faster than migrants. Although migration does not affect the timing of pre-breeding reproductive and metabolic changes, migrant species may need more time to increase their body mass. T levels in resident species may be accelerated by higher spring temperatures that may also advance the pre-breeding preparation of both migrants and residents.

EFFECT OF FASTING REGIMEN AND DIETARY ZINC SUPPLEMENTATION ON HEMATOLOGICAL PARAMETERS, HORMONAL PROFILES AND ANTIOXIDANT PROPERTIES IN MALES OF GROWING RABBITS

The objective of the present study was to evaluate the effect of fasting regimen and dietary zinc (Zn) supplementation on hematological parameters, blood biochemical components, hormonal profiles and the antioxidative properties in males of growing rabbits. A total of 60 weaned male V-Line rabbits (35 days old) were randomly divided into six experimental treatments (10 each): (1) control (basal diet ad labium without any supplementation of Zn); (2) Ad+Zn (basal diet ad labium +100 mg Zn/kg diet); (3) F24 (24 hr fasting regimen per week); (4) F48 (48 hr fasting regimen per week); (5) F24+Zn (24 hr fasting regimen per week+100 mg Zn/kg diet) and (6) F48+Zn (48 hr fasting regimen per week+100 mg Zn/kg diet). All experimental treatments were provided from 35 to 84 day of age. The obtained results showed that fasting regimen (in experimental groups F24 and F48) decreased significantly red blood cells (RBCs) compared with those of control (Ad) or Ad+Zn groups in growing rabbits (P≤ 0.0001). While, group F48 recorded the lowest value of blood hemoglobin concentration (Hb) and packed cell volume (PCV). Dietary Zn supplementation relieved the effect of fasting in groups F24+Zn and F48+Zn. Regarding to white blood cells (WBCs) count, the lowest WBCs number was observed in F48 group compared with other treatments. The highest neutrophils percentages were recorded in groups supplemented with Zn (in groups Ad+Zn, F24+Zn and F48+Zn) compared with the other groups. No significant differences were observed in lymphocytes (%) monocytes (%) eosinophils (%) and basophils (%) among the experimental groups. Feeding growing rabbit's ad libitum diet supplemented with Zn (Ad+Zn) increased significantly blood plasma total protein and albumin concentration comparing with the other experimental groups. However, fasting regimen groups with or without Zn supplementation decreased significantly plasma total protein, albumin, glucose, total lipids, cholesterol and numerically triglycerides concentrations comparing with those fed ad libitum diet with or without Zn supplementation. Growing rabbits exposed to fasting (F24, F48, F24+Zn and F48+Zn groups) had a significant increase in blood plasma aspartate aminotransferase (AST), while, growing rabbits exposed to fasting with Zn (F24 and F48 groups) had a significant increase in blood plasma alanine aminotransferase (ALT) compared with those fed ad libitum diet with or without Zn supplementation (Ad and Ad+Zn groups). Total antioxidant capacity (TAC) was significantly increased in the group fed ad libitum diet supplemented with Zn (Ad+Zn) compared with the other experimental groups. However, TAC was significantly reduced in growing rabbit subjected to fasting regimen (24 or 48 h) and dietary Zn supplementation alleviated this effect and improved TAC significantly. Growing rabbits exposed to fasting (F24, F48, F24+Zn and F48+Zn groups) had a significant increase in plasma malonylaldhyed (MDA) concentration, cortisol, corticosterone and significantly decrease in blood plasma triiodothyronine (T3), thyroxin (T4) compared with those fed ad libitum diet (Ad) and ad libitum diet + Zn (Ad+Zn). It could be concluded that growing rabbits exposed to fasting and fed diet supplemented with or without Zn had a significantly decrease in RBCs, Hb concentration, PCV, plasma total protein, albumin, glucose, total lipids, cholesterol, triglycerides, T3 and T4 concentrations. Interestingly, dietary Zn supplementation improved the antioxidative properties and reduced the rate of lipid peroxidation in growing rabbits subjected to fasting regimen.

Induction of out-of-season egg laying by artificial photoperiod in Yangzhou geese and the associated endocrine and molecular regulation mechanisms

This study was carried out to induce out-of-season breeding, in the summer, and to achieve high reproductive performance using artificial photoperiod manipulation in the long-day breeding Yangzhou goose. Young geese were subject to a two-phase short-to-long (group A) or a three-phase (long-short-long; group B) photoperiod program February through October. Egg-laying was induced to start similarly in both groups in May, increased to a peak level in July, and then decreased gradually through to October. The peak and post-peak laying rates were higher with the three-phase than with the two-phase program. Plasma progesterone concentrations changed similarly in the two groups, increasing from low levels during the pre-lay periods until the peak laying stage, then decreasing with decline in the egg-laying rate. Plasma T3 concentrations increased from the beginning of the experiment to form the first peak under a short photoperiod, declined to a trough at peak lay and then progressively increased to high levels towards the end of the experiment. Plasma T4 concentrations increased throughout the experiment, showing little response to changes in photoperiod. GnIH mRNA expression level in the hypothalamus steadily decreased from high levels under the short photoperiod to a nadir at peak of lay, but was abruptly up-regulated by over a thousand-fold thereafter. This mRNA expression pattern was also shared by GnIHR, VIPR, TRHR, TSH, and PRL genes in the pituitary gland, and to lesser extent, by GnRH, VIP, and TRH genes in the hypothalamus. Pituitary GnRHR mRNA expression levels changed in a similar manner to that of reproductive activities of geese in both groups. FSH beta subunits mRNA expression levels increased to high levels after day 11 of the long photoperiod, and were higher in group B than in group A at peak laying. LH beta gene expression level was similarly upregulated by photoperiod and was higher in group B than in group A when used the multivariable and two-way analyses of variance. Taken together, photoperiod, through regulation of expression of an array of genes in the hypothalamus and pituitary gland, synchronized stimulation and refractoriness of the reproductive system in Yangzhou geese. The higher out-of-season egg laying performance following the three-phase photo-program treatment was mediated by higher FSH beta and LH beta subunit mRNA expression levels.

PLASMA THYROXINE (T4) CONCENTRATION IN ZOO-KEPT BLACK-TAILED PRAIRIE DOGS (CYNOMYS LUDOVICIANUS).

This study was conducted to determine plasma thyroxine (T4) concentrations in zoo-kept black-tailed prairie dogs ( Cynomys ludovicianus ). Thirty-one healthy prairie dogs of both sexes were studied as part of their annual clinical health evaluation, performed under general isoflurane anesthesia. Each animal underwent a complete physical examination, complete blood count, plasma biochemistry, and venous blood gas analysis. Heparinized venous blood samples were collected individually and processed for plasma T4 analysis using a veterinary biochemistry analyzer. The median plasma T4 concentration for the prairie dogs in this study was 4.1 μg/dl (minimum = 0.6 μg/dl; maximum = 8.0 μg/dl). The mean ± standard deviation plasma T4 concentration was 4.49 ± 2.39 μg/dl. No significant differences were found for varying ages, sexes, weights, or housing systems. The data presented in this report can promote better physiologic understanding and improve clinical management of this rodent species.

Disruption of the hypothalamic-pituitary-thyroid axis on co-exposures to dithiocarbamate and neonicotinoid pesticides: Study in a wildlife bird, Amandava amandava

Non-target organisms, including human and wildlife, are susceptible to deleterious effects of pesticide mixtures in their environment. Present study demonstrated the disruption of the hypothalamic-pituitary-thyroid (HPT) axis in a seasonally breeding wildlife bird Amandava amandava on co-exposure to dithiocarbamate mancozeb/MCZ and neonicotinoid imidacloprid/IMI, at concentrations even lower than respective environmentally realistic exposure level of each of the pesticide. Adult male birds (n=8/group) were exposed individually to 0.25% LD50 of each of MCZ (0.14mg) and IMI (2.75μl) followed by co-exposure to their equimixture as MIX-I (0.25% LD50 of each) and MIX-II (0.5% LD50 of each) through food for 30d in preparatory phase of reproductive cycle. Disruptions of thyroid gland and pituitary-thyroid axis were evident. Altered thyroid weight and volume, follicles with inactive colloids and lesions, decrease of height and nucleus-to-cytoplasm ratio of follicular epithelial cells were noted. Plasma levels of T4 and T3 were decreased, more significant in mixture groups than in individually exposed groups. Within co-exposed groups, comparatively high plasma T4 and T3 levels in MIX-II than MIX-I indicated dose non-responsiveness of the pesticides in mixtures; a characteristic displayed by endocrine disrupters. Plasma TSH level was increased in MCZ- and IMI- but decreased in MIX-I and MIX-II suggesting the disruption of the negative feedback and impairment of the HPT axis in co-exposed groups. Effects were more prominent in co-exposed groups due to combinatorial action and cumulative toxicity of pesticides. Considering the role of thyroid hormones in reproductive development, pesticides even in low dose could affect the thyroid homeostasis and reproductive axis.

Transcriptional response to 131I exposure of rat thyroid gland

Humans are exposed to 131I in medical diagnostics and treatment but also from nuclear accidents, and better knowledge of the molecular response in thyroid is needed. The aim of the study was to examine the transcriptional response in thyroid tissue 24 h after 131I administration in rats. The exposure levels were chosen to simulate both the clinical situation and the case of nuclear fallout. Thirty-six male rats were i.v. injected with 0–4700 kBq 131I, and killed at 24 h after injection (Dthyroid = 0.0058–3.0 Gy). Total RNA was extracted from individual thyroid tissue samples and mRNA levels were determined using oligonucleotide microarray technique. Differentially expressed transcripts were determined using Nexus Expression 3.0. Hierarchical clustering was performed in the R statistical computing environment. Pathway analysis was performed using the Ingenuity Pathway Analysis tool and the Gene Ontology database. T4 and TSH plasma concentrations were measured using ELISA. Totally, 429 differentially regulated transcripts were identified. Downregulation of thyroid hormone biosynthesis associated genes (e.g. thyroglobulin, thyroid peroxidase, the sodium-iodine symporter) was identified in some groups, and an impact on thyroid function was supported by the pathway analysis. Recurring downregulation of Dbp and Slc47a2 was found. Dbp exhibited a pattern with monotonous reduction of downregulation with absorbed dose at 0.0058–0.22 Gy. T4 plasma levels were increased and decreased in rats whose thyroids were exposed to 0.057 and 0.22 Gy, respectively. Different amounts of injected 131I gave distinct transcriptional responses in the rat thyroid. Transcriptional response related to thyroid function and changes in T4 plasma levels were found already at very low absorbed doses to thyroid.

Developmental toxicity and thyroid hormone-disrupting effects of 2,4-dichloro-6-nitrophenol in Chinese rare minnow (Gobiocypris rarus)

In the present study, to evaluate embryonic toxicity and the thyroid-disrupting effects of 2,4-dichloro-6-nitrophenol (DCNP), embryos and adults of Chinese rare minnow (Gobiocypris rarus) were exposed to 2, 20, and 200μg/L DCNP. In the embryo-larval assay, increased percentages of mortality and occurrence of malformations, decreased percentage of hatching, and decreased body length and body weight were observed after DCNP treatment. Moreover, the whole-body T3 levels were significantly increased at 20 and 200μg/L treatments, whereas the T4 levels were markedly decreased significantly (p<0.05) for all DCNP concentrations. In the adult fish assay, plasma T3 levels were significantly increased whereas plasma T4 levels were significantly reduced in the fish treated with 20 and 200μg/L (p<0.05). In addition, DCNP exposure significantly changed the transcription levels of thyroid system related genes, including dio1, dio2, me, nis, tr, and ttr. The increased responsiveness of thyroid hormone and mRNA expression levels of thyroid system related genes suggested that DCNP could disrupt the thyroid hormone synthesis and transport pathways. Therefore, our findings provide new insights of DCNP as a thyroid hormone-disrupting chemical.

Thyroid Hormone-Dependent Epigenetic Regulation of Melanocortin 4 Receptor Levels in Female Offspring of Obese Rats.

Maternal obesity is a risk factor for offspring obesity. The melanocortin 4 receptor (Mc4r) is one of the mediators of food intake and energy balance. The present study examined the epigenetic mechanisms underlying altered Mc4r levels in the hypothalamic paraventricular nucleus in the offspring of high-fat diet (HFD)-induced obese dams and sought to elucidate the role of thyroid hormones in epigenetic regulation and tagging of their nucleosome at the Mc4r promoter. Female Wistar rats were fed an HFD or standard chow from weaning through gestation and lactation. Epigenetic alterations were analyzed in the offspring on postnatal day 21 at the Mc4r promoter using chromatin immunoprecipitation and bisulfite sequencing. To study the role of triiodothyronine (T3) in Mc4r downregulation, dams received methimazole (MMI), an inhibitor of thyroid hormone production. Offspring of HFD-fed dams had a greater body weight, elevated plasma T3 concentrations, and lower Mc4r messenger RNA levels than controls. At the Mc4r promoter, offspring of HFD-fed mothers demonstrated increased histone 3 lysine 27 acetylation (H3K27ac) with a greater association to thyroid hormone receptor-β (TRβ), an inhibitor of Mc4r transcription. Moreover, TRβ coimmunoprecipitated with H3K27ac, supporting their presence in the same complex. Maternal MMI administration prevented the HFD reduction in Mc4r levels, the increase in TRβ, and the increase in the TRβ-H3K27ac association, providing further support for the role of T3 in downregulating Mc4r levels. These findings demonstrate that a perinatal HFD environment affects Mc4r regulation through a T3 metabolic pathway involving histone acetylation of its promoter.

Age-related and seasonal variations in plasma uncarboxylated osteocalcin in male Murrah buffaloes

The present study aims to investigate the age-related and seasonal variations in plasma uncarboxylated osteocalcin (UcOCN) in male Murrah buffaloes. In experiment 1, body weight, body dimensions and plasma UcOCN levels were estimated in 120 male Murrah buffaloes aged between 18 days and 8 years. We observed a significant (p < 0.0001) decrease in plasma UcOCN with age and their levels ranged between 0.25 and 9.25 ng/ml. In experiment 2, the plasma UcOCN, cortisol, triiodothyronine (T3), thyroxine (T4) and prolactin levels were determined during spring and summer in 6–34 months (n = 24) old male Murrah buffaloes. Significant (p < 0.0001) higher plasma UcOCN levels were observed in spring than in summer. The plasma T3 and T4 levels were positively correlated with plasma UcOCN, whereas the plasma cortisol and prolactin were negatively correlated. Further, to observe the effect of season on temporal variations of UcOCN, Murrah buffaloes aged between 4–6 (n = 5), 14–16 (n = 5) and 28–30 (n = 5) months were bled at an interval of 30 min, between 0700 and 01030 h, during both the seasons. We observed significant effects of season (p < 0.0001), age (p < 0.0001) and season-by-age interaction (p < 0.01) on plasma UcOCN. The reasons for variations in plasma UcOCN with age and season will be discussed.

Thermal manipulation during late embryogenesis: Effect on body weight and temperature, thyroid hormones, and differential white blood cell counts in broiler chickens

The effects of thermal manipulation (TM) at 38.5°C and 40°C for 6 h at embryonic day (ED) 16, 9 h at ED 17, and 12 h at ED 18 on body weight (BW) and cloacal body temperature (Tb) during the first wk and later at post-hatch d 10, 14, 21, 28, and 42 were evaluated. Furthermore, chicks’ ability to cope with a thermal challenge (TC; 41°C for 6 h) at post-hatch d 14 and 42 was also evaluated. A chick's response to TC was measured by determining the cloacal body temperature; the plasma thyroid hormones (thyroxin (T4) and triiodothyronine (T3)); the packed cell volume (PCV); the heterophil (H), lymphocyte (L), monocyte, basophil, and eosinophil percentages; and the heterophil-to-lymphocyte ratios (H/L). Thermal manipulation did not affect the hatchability. However, the body weight of TM chicken was higher compared with controls at marketing age (post-hatch d 42). At post-hatch d 14 and 42, no significant changes in Tb were observed among the different treatment groups. However, during TC at d 14 and 42, the Tb of TM chicks was lower compared with the controls. During TC, a significant increase in plasma T4 and a significant decrease in plasma T3 of TM chicks compared with controls were reported. Furthermore, during TC, a significant increase in the PCV and heterophil, monocyte, and H/L ratios, and a reduction in the lymphocyte percentages also were observed in TM chicks compared with the controls. Results of this study showed that chicks subjected to heat manipulation during late embryogenesis respond better to heat stress later in the growth and development period.

Alterations in the hypothalamic pituitary thyroid axis in animals submitted to early-life trauma

Introduction: Changes in maternal care can affect offspring’s thyroid hormone T3 levels. Pups from highly caring mothers have higher levels of thyroid hormone T3. In humans, physical abuse in childhood is related to lower levels of T3 in adolescence. This study aimed at verifying if early-life trauma in rodents is correlated with T3 levels in adulthood. Methods: From the second day of life, litters of Wistar rats were subjected to reduced nesting material (Early–Life Stress-ELS) or standard care (Controls). In adult life, the animals were chronically exposed to standard diet or standard diet + palatable diet and plasma T3 levels were measured before and after the exposition to diet. Results: Thyroid hormone T3 levels in adult life correlated negatively with the licking and grooming (LG) scores in the ELS group. This correlation disappeared when the animals had the opportunity to choose between two diets chronically. Conclusion: The adverse environment affected maternal behavior and caused marks on the metabolism of the intervention group (T3), which were reverted by chronic palatable food consumption. Keywords: Trauma; T3; stress