Serum Thyroxine Concentrations Research Articles

Effect of iodinated radiographic contrast media on radioimmunoassay for measuring thyroid hormones

Radioimmunoassay (RIA) is one of the most routine laboratory tests for diagnosing thyroid disease. Patients might receive iodine in the form of intravenous iodinated radiographic contrast media (IRCM) before testing of serum thyroxin (T4) or triiodothyronine (T3) concentration by RIA. The objective was to determine the effect of IRCM on T4 and T3 hormone tests in normal, hypothyroid, and hyperthyroid hormone conditions by RIA. IRCMs (0, 2.5, 5 and 10 mgI/mL) used in this study were iopromide and iodixanol. RIA was determined by commercial T4 RIA kit and T3 RIA kits. The method suggested by the manufacturer was followed. Normal, hypothyroid, and hyperthyroid hormones condition were 1.2 ng/mL, 0.2 ng/mL and 2.2 ng/mL for T3 hormone concentration and 70 ng/mL, 30 ng/mL and 140 ng/mL for T4 hormone concentration, respectively. %Bound values were compared between IRCM-incubated groups and non-incubated group. The data showed that iopromide-incubated groups did not statistically significant change %bound values of T3 and T4 hormone tests in normal, hypothyroid, and hyperthyroid conditions, compared to the non-incubated group. In the same way, %bound values of T3 and T4 hormone tests in iodixanol-incubated groups did not change at all conditions when compared to the non-incubated group. This finding suggested that iodinated radiographic contrast media was unlikely to result in significant problems with radioimmunoassay for measuring T3 and T4 thyroid hormones.

Effects of pre-incubation storage duration and nonventilation incubation procedure on embryonic physiology and post-hatch chick performance

This study investigated the effects and possible interactions of storage and nonventilation during incubation for eggs from Sasso broiler breeder flock on pre- and post-hatch incubation results.A total of 1,260 Sasso eggs from a 58-wk-old broiler breeder flock were individually numbered, weighed and stored for 7 d or for 18 d in a climate-controlled room (16°C, 75% RH). After storage, eggs were weighed, and randomly assigned equally into 2 incubators. One of the incubators was ventilated (V) for the entire incubation and the second was nonventilated (NV) for the first 12 d. At d 18, the eggs were weighed, candled, and fertile eggs were transferred from the turning trays to hatching baskets. During the last 3 d of incubation, hatching eggs were checked individually every 3 h for hatching events and hatchability of fertile eggs. After pull out at d 21.5, post-hatch performances was determined until 1 wk of age.Results showed that, embryo weights from eggs in NV incubator was significantly higher (P < 0.05) in both stored eggs compared to those from eggs in ventilated incubator, but embryos from eggs stored for 18 d were smaller (P < 0.05) than those from eggs stored for 7 d. Hatchability was higher (P < 0.0001) in NV incubator compared to V incubator in both 7 d and 18 d stored eggs and an interaction was found between incubation ventilation and storage duration on both hatchability and embryonic mortality (P < 0.0001). Chick weights from NV incubator at 7 d post-hatch was greater (P = 0.0009) than those from V incubator. Serum Tri-iodothyronine (T3) and Thyroxin (T4) concentrations were significantly higher (P < 0.05) in NV compare to V group.It was concluded that the effect of long-term pre-incubation storage on embryonic physiology and post-hatch growth interacted significantly with incubation ventilation and that nonventilation can compensate for the negative effects of storage on some hatching and post-hatch performances.

Comparison of the Vcheck and IMMULITE 2000 methods for T4 measurement in canine and feline serum

The aim of this study was to compare canine and feline thyroxine (T4) results obtained by the Vcheck method with those obtained by the IMMULITE 2000 immunoassay, which had previously been validated for canine serum. The concentration of T4 in 53 canine and 44 feline serum samples was determined concurrently by the Vcheck and IMMULITE methods, the latter as the reference method. The T4 values were compared using the IMMULITE Youden plot and Deming regression analysis. According to the regression analysis, the two methods gave comparable results. Spearman’s correlation shows a very high consistency of the results obtained by the two analyzers. The results of the Vcheck method were comparable to those of the IMMULITE 2000 reference method, so Vcheck may be used as an alternative assay to evaluate the serum thyroxine concentration in dogs and cats for the diagnosis of thyroid gland disease.

A dosing algorithm for individualized radioiodine treatment of cats with hyperthyroidism.

BackgroundRadioiodine (131I) is the treatment of choice for hyperthyroidism in cats, but current 131I‐dosing protocols can induce iatrogenic hypothyroidism and expose azotemia.ObjectivesTo develop a cat‐specific algorithm to calculate the lowest 131I dose to resolve hyperthyroidism, while minimizing risk of iatrogenic hypothyroidism and subsequent azotemia.AnimalsOne thousand and four hundred hyperthyroid cats treated with 131I.MethodsProspective case series (before‐and‐after study). All cats had serum concentrations of thyroxine (T4), triiodothyronine (T3), and thyroid‐stimulating hormone (TSH) measured (off methimazole ≥1 week). Using thyroid scintigraphy, each cat's thyroid volume and percent uptake of 99mTc‐pertechnatate (TcTU) were determined. An initial 131I dose was calculated by averaging dose scores for T4/T3 concentrations, thyroid volume, and TcTU; 80% of that composite dose was administered. Twenty‐four hours later, percent 131I uptake was measured, and additional 131I administered, as needed, to deliver an adequate radiation dose to the thyroid tumor(s). Serum concentrations of T4, TSH, and creatinine were determined 6 to 12 months later.ResultsThe median calculated 131I dose was 1.9 mCi (range, 1.0‐10.6 mCi); 1380 cats required additional 131I administration on day 2. Of the cats, 1047 (74.8%) became euthyroid, 57 (4.1%) became overtly hypothyroid, 240 (17.1%) became subclinically hypothyroid, and 56 (4%) remained hyperthyroid. More overtly (71.9%) and subclinically (39.6%) hypothyroid cats developed azotemia than euthyroid cats (14.2%; P < .0001).Conclusions and Clinical ImportanceOur algorithm for calculating individual 131I doses resulted in cure rates similar to historical treatment rates, despite much lower 131I doses. This algorithm appears to lower prevalence of both 131I‐induced overt hypothyroidism and azotemia.

Testing for heterotopia formation in rats after developmental exposure to selected in vitro inhibitors of thyroperoxidase

The thyroperoxidase (TPO) enzyme is expressed by the thyroid follicular cells and is required for thyroid hormone synthesis. In turn, thyroid hormones are essential for brain development, thus inhibition of TPO in early life can have life-long consequences for brain function. If environmental chemicals with the capacity to inhibit TPO in vitro can also alter brain development in vivo through thyroid hormone dependent mechanisms, however, remains unknown. In this study we show that the in vitro TPO inhibiting pesticide amitrole alters neuronal migration and induces periventricular heterotopia; a thyroid hormone dependent brain malformation. Perinatal exposure to amitrole reduced pup serum thyroxine (T4) concentrations to less than 50% of control animals and this insufficiency led to heterotopia formation in the 16-day old pup’s brain. Two other in vitro TPO inhibitors, 2-mercaptobenzimidazole and cyanamide, caused reproductive toxicity and had only minor sporadic effects on the thyroid hormone system; consequently, they did not cause heterotopia. This is the first demonstration of an environmental chemical causing heterotopia, a brain malformation until now only reported for rodent studies with the anti-thyroid drugs propylthiouracil and methimazole. Our results highlight that certain TPO-inhibiting environmental chemicals can alter brain development through thyroid hormone dependent mechanisms. Improved understanding of the effects on the brain as well as the conditions under which chemicals can perturb brain development will be key to protect human health.

Progesterone supplementation in Holstein heifers subjected to cooling and timed AI during summer: physiological and reproductive variables and thyroid hormone concentrations.

Our aim was to evaluate the effects of progesterone supplementation after fixed-time artificial insemination (FTAI) on physiological and reproductive variables and serum thyroid hormone concentrations of cooled Holstein heifers during a hot summer season. Sixty-nine Holstein heifers were randomly assigned to three treatments: (1) heifers under visual estrus detection and inseminated according to AM-PM rule (n = 23; control (C)), (2) heifers subjected to FTAI after estrus synchronization using a CIDR insert (n = 24; FTAI group), and (3) heifers treated as the FTAI group plus progesterone supplementation between the day 4 and 14 post-insemination with a reused CIDR device (n = 22; FTAI+SP4 group). All heifers were cooled daily with misting and fans. Physiological variables were measured; likewise, blood samples were collected to determine serum progesterone, thyroxine, and triiodothyronine concentrations. Both respiration rate and rectal temperature were similar among treatments. Conception rate was greater (P < 0.05) in C (65.2%) and FTAI+SP4 (59.1%) heifers than in FTAI heifers (33.3%). Serum triiodothyronine and progesterone concentrations of FTAI+SP4 heifers were similar to those of C heifers but greater (P < 0.05) than those of FTAI heifers. In conclusion, progesterone supplementation post-insemination increased conception rate and serum progesterone concentrations without affecting thermoregulation capacity in Holstein heifers subjected to FTAI and cooling during a hot summer season.

Endocrine profiles and kidney function markers of apparently healthy pregnant and lactating Duroc sows

This experiment was carried out to evaluate the effects of reproductive activities (pregnancy and lactation) on certain serum endocrine profiles and kidney function markers of Duroc sows. Thirty (30) sexually matured cycling apparently healthy Duroc sows and eight (8) Duroc boars (38 pigs), of mean weight 55.36±0.48 kg, aged between13and 15 months were used for this study. The sows (30) were randomly assigned to five groups (A to E) of six sows per group in a completely randomized design (CRD). Group A: Nonpregnant (control), Group B: Early gestation (38 days), Group C: Mid gestation (78 days), Group D: Late gestation (110 days) and Group E: Post gestation (7 days postpartum). The mean serum progesterone (P4) concentration of group D sows was significantly (p&lt;0.05) increased when compared to group E. The mean serum thyroxine (T4) concentration of group D sows (3rd trimester) was significantly (p&lt;0.05) increased when compared to groups C and E. The mean blood urea nitrogen (BUN) concentration of the treated group (C) was significantly (p&lt;0.05) higher when compared to group B. The mean creatinine concentration of group D was significantly (p&lt;0.05) higher when compared to groups E, B and the control. The mean BUN/CRT ratio of group B sows was significantly (p&lt;0.05) higher when compared to groups C, D, E and the control. There were, however, no significant variations (p&gt;0.05) in the mean oestradiol (E2), cortisol (C), creatinine (CRT) concentrations and BUN/CRT ratio among all the groups. In conclusion, the serum endocrine and kidney function markers of Duroc sows in this study were significantly influenced by gestation. This study has established reference values of the endocrine profiles and kidney function markers of Duroc sows during gestation that are consistent with normal health.

Evaluation of serum analytes in pregnant and non-pregnant dairy cows as indicators of pregnancy

This study was conducted to reveal the dynamics of haematological indicators in pregnant and non-pregnant dairy cows. Sixty multiparous healthy dairy cows were divided into four groups based on the length of time they had been pregnant, namely first, second and third trimesters, and non-pregnant (n=15 each). Blood was collected from each animal, and serum was harvested and stored at -20 °C for biochemical profiling. Concentrations of serum total oxidants (TOC), ceruloplasmin oxidase (CpO) and triiodothyronine (T3) were higher (P &lt;0.05) during the third trimester compared with non-pregnant cows. Serum arylesterase (Ary) concentration was lower (P &lt;0.05) during the second and the third trimesters compared with the non-pregnant cows. The concentration of serum total homocysteine (tHcy) was higher (P &lt;0.05) the third trimester compared with the first and the second trimesters. The concentrations of serum total antioxidants (TAC), paraoxonase 1 (PON1), thyroxine (T4), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not different in the pregnant and the non-pregnant cows. Thus, TOC, Ary, CpO, tHcy and T3 could be taken as biological markers to assess the progression of pregnancy and to develop management tools to improve health status during late gestation in dairy cows&#x0D; Keywords: ceruloplasmin, hepatic enzymes, late gestation, triiodothyronine

Correlation between sperm parameters and circulating thyroid hormones and testosterone concentrations in Labrador Retriever dog

Thyroid hormones physiologically regulate the semen quality, by altering testosterone concentrations, and different seminal parameters, as well as sperm motility, viability and semen volume. Serum thyroxine (T4), free thyroxine (fT4), thyroid-stimulating hormone (TSH) and testosterone (T) concentrations were measured in 26 adult Labrador Retriever dogs (n. 20 normospermic and n. 6 azoospermic groups), aged 3 ± 0.5 years old, to determine their specific references, by taking into account the related conventional and kinematic sperm parameters and clinical ultrasound evaluations. The mean values of T4, fT4, TSH and T concentrations, as soon as those of sperm parameters and clinical evaluations of normospermic group were in line with dog’s physiological range of literature data. Normospermic group showed significant correlations between T4 and T (r = −0.681; p < .01), sperm progressive motility (%) (r = −0.623; p < .01), and sperm non-progressive motility (%) (r = 0.625; p < .02). The azoospermic group showed higher T4, fT4, TSH and lower T concentrations, compared to normospermic group, and a positive correlation between T4 and T (r = 0.8548; p < .046). The use of breed-specific hormonal ranges and sperm parameters will improve the knowledge of their interaction in Labrador Retriever dogs, adding a new segment of scientific literature. Highlights Thyroxine (T4), free thyroxine (fT4), thyroid stimulating hormone (TSH) and testosterone (T) concentrations were measured in male dogs. Conventional and kinematic sperm parameters were also evaluated. Dogs were divided in 20 normospermic and n. 6 azoospermic Labrador Retrivers. Azoospermic group showed higher values of T4, fT4, TSH and lower values of T compared to normospermic Use of breed-specific hormonal ranges and sperm parameters will improve the knowledge of scientific literature.

Serum thyroxine and thyrotropin concentrations decrease with severity of nonthyroidal illness in cats and predict 30-day survival outcome.

BackgroundIn cats, nonthyroidal illness affects serum thyroid hormone concentrations. Serum thyroxine (T4) and triiodothyronine (T3) concentrations commonly decrease, whereas free T4 (fT4) concentrations vary unpredictably. Limited information exists regarding effects on serum thyrotropin (thyroid‐stimulating hormone [TSH]) concentrations in cats with nonthyroidal illness syndrome (NTIS).ObjectivesTo characterize alterations in thyroid function that develop in cats with NTIS and to correlate these alterations with severity and outcome of the nonthyroidal illness.AnimalsTwo hundred and twenty‐two cats with NTIS and 380 clinically normal cats of similar age and sex.MethodsProspective, cross‐sectional study. All cats had serum T4, T3, free T4, and TSH concentrations measured. Cats were grouped based on illness severity and 30‐day survival.ResultsCats with NTIS had lower serum T4 and T3 concentrations than did normal cats (P < .001). Serum fT4 and TSH concentrations did not differ between groups. Serum T4, T3, and fT4 concentrations progressively decreased with increasing disease severity (P < .001). The 56 cats that died had lower T4, T3, and TSH concentrations than did the 166 survivors, with no difference in fT4 concentration. Multivariable logistic regression modeling indicated that serum T4 and TSH concentrations both predicted survival (P < .02).Conclusions and Clinical ImportanceCats with NTIS commonly develop low serum T4, T3, and TSH concentrations, the prevalence and extent of which increases with disease severity. Clinicians should consider evaluating thyroid function in cats with severe NTIS, because doing so could help determine probability of successful treatment responses before investing considerable time, effort, and finances in addressing the underlying disease.

Clinical and diagnostic findings in a dog and a cat with congenital hypothyroidism

A seven-year-old Miniature Schnauzer and a 16-month-old Domestic shorthair with clinical features of disproportionate dwarfism, presented with progressive thoracolumbar and cervical myelopathies, respectively. CT and MR imaging were performed in...

Serum concentration of thyroxine and triiodothyronine in newborn calves from cows supplemented with barium selenate

Background: Barium selenate is an inorganic source of selenium (Se) used in prolonged-release preparations to treat selenium deficiency in bovines. Objective: To evaluate serum concentrations of triiodothyronine (T3) and thyroxine (T4) hormones in newborn calves from mothers supplemented with barium selenate during prepartum. Methods: Six black Frisian pregnant cows were supplemented with barium selenate subcutaneously during the last two months of gestation, until calving. Six cows were used as controls. All cows were subjected to a low Se diet, consisting of hay from natural pasture and commercial concentrate lacking Se. The Se balance was measured through the activity of erythrocyte glutathione peroxidase (GPx). Serum concentration of T3 and T4 in calves was determined by electrochemiluminescence. Results: Se supplementation during prepartum increased GPx activity in cows from day 45 post-supplementation (p&lt;0.05). Calves from supplemented mothers showed higher average serum Se concentration than calves from non-supplemented mothers. The average concentration of T3 in the calves from supplemented mothers was lower in the first hour of life (p&lt;0.05) compared with calves from mothers of the non-supplemented group. A decrease (p&lt;0.05) in T4 serum concentrations was observed in both groups at seven days of age. Conclusions: Administration of barium selenate to cows during prepartum generates a reduction in serum concentration of T3 in the first hour of life of calves.

Physiological responses of Holstein calves to hot weather conditions.

The objectives of the study described were to (1) compare environmental temperature-humidity index (THI) with the THI measured within two different calf housing systems and (2) determine how THI affects Holstein heifer calf body temperatures, serum cortisol concentrations, and serum thyroxine concentrations. At 24 to 48h of age, calves were assigned to one of two individual housing treatments: (1) stalls in a three-sided barn (n = 8) or 2) hutches placed outside (n = 8). Calves were observed until 42days of age during the summer months. Ambient temperature and relative humidity within housing systems were recorded hourly. Calf body temperatures were measured hourly using devices attached to the underside of each calf's tail. Blood samples were collected at 7, 21, and 42days of age via jugular venipuncture. Blood serum was analyzed for cortisol and thyroxine concentrations using enzyme-linked immunosorbent assays (ELISAs). Overall average THI was higher in hutches than in stalls (P < 0.0001). Calves housed in hutches had higher body temperatures (39 ± 0.18°C vs 38 ± 0.15°C, P = 0.005). No differences occurred in serum cortisol concentrations (P = 0.89) but at 21days of age, calves housed in hutches had higher serum thyroxine concentrations (16.55 ± 0.51μg/dl vs 13.91 ± 0.54μg/dl, P = 0.0006) than calves housed in stalls. Although both housing systems in this study were located on the same dairy, calves housed in hutches were exposed to higher THI values, had higher body temperatures, and at 21days of age had higher serum thyroxine concentrations than calves housed in stalls inside a three-sided barn.

Stress Associated with Simulated Transport, Changes Serum Biochemistry, Postmortem Muscle Metabolism, and Meat Quality of Broilers.

Simple SummaryThe objective of this study was to investigate the effects of the transportation on broilers through the use of a vibration and motion simulation machine. Short-term transport stress induced significant physiological changes in broiler chickens. Simulation of the vibration and motion associated transport for 2 h altered hormonal secretion and blood biochemical characteristics. However, after 4 h, the birds appear to regain homeostatic equilibrium. Despite this, the stress activated antioxidant defenses, acidified muscles and increased peroxidation, as well as decreasing the meat quality of broilers. This study supports and extends previous work that identified transportation as a major risk in relation to bird welfare and meat quality.Many factors contribute to the stress of transporting broilers from the farm to the processing plant. Using a motion simulation machine, a total of 144 male broilers were employed to determine the effect of motion, vibration, and feed withdrawal during transportation on serum biochemical parameters, postmortem muscle metabolism, and meat quality of broilers. The results indicated that transportation did not affect the activity of lactate dehydrogenase, γ-glutamyl transferase, aspartate aminotransferase, creatine kinase, and glucose in the serum, glutathione peroxidase in the breast and thigh muscle, nitric oxide synthase (NOS) in the breast, and heat stress protein 70 mRNA expression level in the liver (p > 0.05). Serum triiodothyronine, thyroxine, and insulin concentration declined with 2 h transportation (p < 0.05) and recovered with 4 h transportation (p < 0.05). NOS concentration in the thigh increased with 2 h transportation (p < 0.05) and recovered with 4 h transportation (p < 0.05). Two-hour and 4 h transportation increased the activity of superoxide dismutase in both muscles. Malondialdehyde, lactic acid, and drip loss24 h in both thigh and breast muscles increased, and glycogen in both muscles decreased with increasing transportation times (p < 0.05). Two-hour transportation did not influence pH45 min and pH24 h in the breast and thigh muscle, but these indexes decreased with 4 h transportation. This experiment supports and extends previous work that identified transportation as a major risk in relation to bird welfare and meat quality.

Hyperthyroidism is not a risk factor for subclinical bacteriuria in cats: A prospective cohort study.

BackgroundSubclinical bacteriuria is defined as a positive bacterial urine culture in the absence of clinical evidence of urinary tract infection (UTI). Studies have reported that hyperthyroid cats have UTIs (mostly subclinical) with prevalence rates of 12%‐22%. Consequently, clinicians consider hyperthyroidism a risk factor for development of subclinical bacteriuria, and many recommend urine culture when evaluating hyperthyroid cats.ObjectivesTo compare the prevalence of subclinical bacteriuria (based on positive urine culture) in untreated hyperthyroid cats to that in euthyroid cats of similar age and sex.AnimalsThree hundred and ninety‐three hyperthyroid cats presented for radioiodine treatment and 131 euthyroid cats (≥7 years of age) presented for routine examination. Cats with signs of lower urinary tract disease were excluded.MethodsProspective cohort study. Both hyperthyroid and euthyroid cats had urine collected by cystocentesis for complete urinalysis and culture. Data pertaining to age, sex, body condition, and serum thyroxine and creatinine concentrations also were acquired. Logistic regression was performed to evaluate for potential risk factors for subclinical bacteriuria.ResultsHyperthyroid cats showed a low prevalence of subclinical bacteriuria (4.3%), which did not differ from that found in euthyroid cats (4.6%). Of the signalment factors evaluated, only female sex was a significant risk factor (odds ratio [OR], 6.9; P = .002). Furthermore, positive urine cultures were more likely in specimens with dilute urine concentration (<1.035), pyuria, or microscopic bacteriuria.Conclusions and Clinical ImportanceHyperthyroid cats are not at risk for subclinical bacteriuria. In the absence of lower urinary tract signs, no clinical benefit exists in routinely performing urine cultures when evaluating hyperthyroid cats.

Dynamics of thyroid hormones in Stavropol breed sheep in postnatal ontogenesis

The aim of the research was to study the dynamics of thyroid hormones and thyroid-stimulating hormone of the pituitary gland in Stavropol breed sheep in postnatal ontogenesis and the establishment of thyroid status in animals before insemination, during pregnancy and after childbirth. Determination of concentration of total triiodothyronine, free thyroxine and thyroid stimulating hormone in serum was performed by solid-phase enzyme immunoassay (ELISA) using standard test systems. As a result of the studies, the level of thyroid hormones and thyroid-stimulating hormone in the blood of sheep of Stavropol breed in postnatal ontogenesis was determined. It was established that at the birth of lambs, the lowest level of triiodothyronine (2.55 ± 0.04 nmol/l), thyroxine (19.47 ± 0.45 pmol/l) and thyrotropic (0.31 ± 0.05 Mme/ml) hormone was observed in the blood, compared with other age periods. By the age of three months, the levels of triiodothyronine and thyroxine increased significantly by 7.7% and 24.8%, respectively. When comparing the data in six monthly young ewes, the concentration of all studied hormones was the highest in comparison with other age groups (triiodothyronine – 3.11 ± 0.21 nmol/l; thyroxine – 26.29 ± 0.97 pmol/l; thyrotropic hormone – 0.81 ± 0.09 Mme/ml). In the age of nine months, a significant decrease in triiodothyronine by 16.8%, thyroxine - by 13.2% and thyroid-stimulating hormone - by 34.6% was observed, compared with ewes of 6 month old. By the age of 12 months, only free thyroxine was significantly changed, its serum concentration increased by 9.5% and amounted to 25.21 ± 0.31 pmol/l, compared with the data of nine-month-old sheep. It was found that the concentration of triiodothyronine changes significantly in sheep after childbirth and is 2.53 ± 0.03 nmol/l, which is 6.3% more than in pregnant ewes. The level of thyroxine on the 90th day of pregnancy decreases by 5.3%, and by the 135th day by 16%, compared with the previous period of the study. Thyroid-stimulating hormone in the blood serum of sheep on the 90th day of pregnancy becomes significantly lower by 29% (p ⩽ 0.05) than its concentration in non-pregnant ones. After childbirth, thyroid-stimulating hormone significantly increased by 26.66% (p ⩽ 0.05). As a result of the studies, in sheep of Stavropol breed, standard sizes of the level of thyroid gland hormones (triiodothyronine, thyroxine) and thyroid-stimulating hormone were established.

Effect of in Ovo Inoculation of Bifidobacterium spp. on Growth Performance, Thyroid Activity, Ileum Histomorphometry, and Microbial Enumeration of Broilers.

Early colonization by beneficial bacteria stimulates the function and development of the digestive tract, on which the performance and vitality of broilers rely. This experiment evaluated the effects of in ovo injection of bifidobacteria on the performance, thyroid activity, bacterial enumeration, and ileal histomorphometry of broiler chickens. A total of 360 fertile eggs were inoculated into the yolk sac, on day 17 of embryogenesis, and allocated to six experimental groups: negative control (not injected, G1), positive control (injected with sterilized distilled water, G2), and groups inoculated with 2 × 108 CFU of Bifidobacterium bifidum, G3; B. animalis, G4; B. longum, G5; or B. infantis, G6. The results revealed an increase (P < 0.01) in body weight and weight gain in all treated groups increases of at least 5.38 and 8.27%, respectively, compared with the control. Feed consumption was not affected during all experimental periods, while the feed conversion ratio (FCR) was enhanced (P < 0.01) only for the overall experimental period (1-28 days of age). The G3 birds recorded the lowest FCR (1.38), while the highest was observed in G1 birds (1.57). Serum concentrations of thyroxin and triiodothyronine were elevated (P < 0.05) with probiotic inoculation. The antioxidant status and immune response of bifidobacteria injected birds were improved; the serum contents of superoxide dismutase and immunoglobulins Y, M, and A were increased (P < 0.05 and P < 0.01), while the malondialdehyde content was decreased (P < 0.01). Ileal architecture was improved in the bifidobacteria treated groups; the highest values of villus height and the villus height/crypt depth ratio were recorded in G3 (936.6 and 11.80) compared with those of G1 (537.1 and 6.93). Moreover, ileal lactic acid bacteria and Bifidobacterium spp. counts increased by at least 10.64 and 51.75%, while total coliform and bacterial counts reduced by at least 15.46 and 15.18%, respectively, compared with those of the control. In conclusion, all tested strains of bifidobacteria enhanced broiler growth performance, ileal function, and thyroid hormone metabolism without obvious differences among them.

Age effect on thyroid hormone brain response in male mice

Thyroid hormones (TH) are important for brain development and central nervous system (CNS) function. Disturbances of thyroid function occur with higher prevalence in the ageing population and may negatively impact brain function. We investigated the age impact on behavior in young adult and old male mice (5 vs. 20 months) with chronic hypo- or hyper-thyroidism as well as in sham-treated controls. Expression of TH transporters and TH responsive genes was studied in CNS and pituitary by in situ hybridization and qRT-PCR, whereas TH serum concentrations were determined by immunoassay. Serum TH levels were lower in old compared with young hyperthyroid mice, suggesting a milder hyperthyroid phenotype in the aged group. Likewise, elevated plus maze activity was reduced in old hyperthyroid animals. Under hypothyroid conditions, thyroxine serum concentrations did not differ in young and old mice. Both groups showed a comparable decline in activity and elevated anxiety levels. However, an attenuated increase in hypothalamic thyrotropin releasing hormone and pituitary thyroid stimulating hormone transcript expression was found in old hypothyroid mice. Brain expression of monocarboxylate transporter 8 and organic anion transporting polypeptide 1c1 was not affected by age or TH status. In summary, ageing attenuates neurological phenotypes in hyperthyroid but not hypothyroid mice, which fits with age effects on TH serum levels in the animals. In contrast no changes in TH transporter expression were found in aged mouse brains with hyper- or hypo-thyroid state.

Thyroid receptor antagonism as a contributory mechanism for adipogenesis induced by environmental mixtures in 3T3-L1 cells

We previously demonstrated that indoor house dust extracts could induce adipogenesis in pre-adipocytes, suggesting a potential role for indoor contaminant mixtures in metabolic health. Herein, we investigated the potential role of thyroid receptor beta (TRβ) antagonism in adipogenic effects (dust-induced triglyceride accumulation and pre-adipocyte proliferation) following exposure to environmental mixtures (indoor house dust extracts). Concentrations of specific flame retardants were measured in extracts, and metabolic health information was collected from residents (n = 137). 90% of dust extracts exhibited significant adipogenic activity, >60% via triglyceride accumulation, and >70% via pre-adipocyte proliferation. Triglyceride accumulation was positively correlated with concentrations of each of twelve flame retardants, despite most being independently inactive; this suggests a putative role for co-exposures or mixtures. We further reported a positive correlation between dust-induced triglyceride accumulation and serum thyroid stimulating hormone concentrations, negative correlations with serum free triiodothyronine and thyroxine concentrations, and a positive and significant association between dust-induced triglyceride accumulation and residents' body mass index (BMI). We hypothesized that inhibition of TR antagonism might counteract these effects, and both addition of a TR agonist and siRNA knock-down of TR resulted in decreased dust-induced triglyceride accumulation in a subset of samples, bolstering this as a contributory mechanism. These results highlight a contributory role of environmental TR antagonism as a putative factor in metabolic health, suggesting that further research should evaluate this mechanism and determine whether in vitro adipogenic activity could have utility as a biomarker for metabolic health in residents.

Chavibetol corrects thyrotoxicosis through alterations in thyroid peroxidase

Thyrotoxicosis is a clinical syndrome that commonly results from excess secretion and/or release of thyroid hormones in the circulation. It affects most of the body systems and if not treated properly may lead to serious health problems. In this investigation, we isolated a phenolic compound, chavibetol (CHV) from Piper betel leaf and evaluated its possible ameliorative effects in thyrotoxicosis of rats. Adult female rats were rendered thyrotoxic by the administration of L-thyroxine (L-T4) at 500μg/kg/day, i.p., for 12days, and then chavibetol (20.0mg/kg, p.o.) was administered for 2weeks. L-T4 administration elevated the concentration of serum thyroxine and triiodothyronine, activities of alanineaminotransferase and aspartate aminotransferase, and decreased the thyrotropin level as well as the expression of thyroid peroxidase (TPO). Further, it increased the activities of hepatic 5'mono-deiodinase-I, glucose-6--phosphatase, sodium-potasium-ATPase, and lipid peroxidation, and depleted the cellular antioxidants. However, chavibetol treatment to thyrotoxic rats normalized almost all these indices including TPO and also preserved the integrity of thyroid tissues suggesting its potential to correct thyrotoxicosis. Effects of CHV were more or less similar to a conventional antithyroid drug, propylthiouracil (PTU).