Farnesoid X receptor up-regulates thyrotropin embryonic factor and attenuates pathological injury of Con A-induced hepatitis

AIM：To observe how farnesoid X receptor (FXR) functioned in concanavalin A (Con A) -induced hepatitis (CIH) and the regulation of FXR-thyrotropin embryonic factor (TEF) pathway. METHODS：C57BL/6 mice were injected with Con A to induce hepatitis. The expression of FXR and TEF in the liver specimens was determined by qRT-PCR and Western blotting. The concentrations of serum ALT/AST and inflammatory cytokines IFN-γ, TNF-α, IL-4 and IL-2 in the blood samples were tested after Con A injection. RESULTS：FXR was down-regulated in CIH mice. TEF was up-regulated when FXR was activated by chenodeoxycholic acid (CDCA). Activation of FXR reduced the levels of aminotransferases and inflammatory cytokines IFN-γ, TNF-α, IL-4 and IL-2 in the CIH mice induced by Con A injection. CONCLUSION：FXR activation attenuates CIH mouse liver injury and reduces inflammatory cytokines. FXR activation results in TEF up-regulation. The FXR-TEF pathway may play a protective role in autoimmune hepatitis.     

Chicken folliculo-stellate cells express thyrotropin receptor mRNA

We investigated the presence of thyrotropin receptor (TSHR) mRNA in chicken pituitary and brain, and quantified the changes in its expression during the last week of embryonic development. We found that in the pituitary gland, TSHR mRNA co-localizes with folliculo-stellate cells but not with thyrotropic cells, suggesting the existence of a paracrine ultra-short thyrotropin feedback loop. TSHR mRNA was also present throughout the diencephalon and various other brain regions, which implies a more general function for thyrotropin in the avian brain. During late embryogenesis, when the activity of the hypothalamo-pituitary-thyroidal axis increases markedly, a significant rise in TSHR mRNA expression was observed in pituitary, which may signify an important change in pituitary ultra-short thyrotropin feedback regulation around the period of hatching.     

Thyroid Function in Anhidrotic Horses

Background: This study was performed to determine whether anhidrotic horses have altered thyroid function compared with horses that sweat normally.
Hypothesis: Anhidrotic horses have normal thyroid function.
Animals: Ten client-owned horses with clinical signs of anhidrosis were paired with 10 horses living in the same environment that had normal sweat production.
Methods: Horses were diagnosed as having normal sweat production or being anhidrotic based on responses to intradermal injections of terbutaline and physiologic responses to lunging exercise. Control horses were selected from the same environment and matched as closely as possible to anhidrotic horses in terms of age, sex, breed, and athletic condition. Thyrotropin-releasing hormone (TRH) stimulation tests were performed in both horses at the same time, once in the summer or fall, and once again in winter.
Results: Anhidrotic horses produced less sweat in response to intradermal injections of terbutaline and exercise than did control horses. They also had greater increases in body temperature and respiratory rate in response to exercise. Resting concentrations of thyroid hormones and thyroid-stimulating hormone (TSH) were not different between anhidrotic and control horses. Thyroid hormone responses to TRH also were not different between the 2 groups of horses. However, anhidrotic horses had a significantly different TSH response to TRH compared with control horses, particularly in the winter.
Conclusions and Clinical Importance: The biologic relevance of the altered TSH response to TRH in anhidrotic horses is uncertain, considering that TSH concentrations remained within previously reported normal ranges and thyroid hormone responses were not different between anhidrotic and control horses.     

Adenohypophyseal Function in Dogs with Primary Hypothyroidism and Nonthyroidal Illness

Background: A recent study of dogs with induced primary hypothyroidism (PH) demonstrated that thyroid hormone deficiency leads to loss of thyrotropin (TSH) hypersecretion, hypersomatotropism, hypoprolactinemia, and pituitary enlargement with large vacuolated "thyroid deficiency" cells that double-stained for growth hormone (GH) and TSH, indicative of transdifferentiation of somatotropes to thyrosomatropes.
Hypothesis: Similar functional changes in adenohypophyseal function occur in dogs with spontaneous PH as do in dogs with induced PH, but not in dogs with nonthyroidal illness (NTI).
Animals: Fourteen dogs with spontaneous PH and 13 dogs with NTI.
Methods: Adenohypophyseal function was investigated by combined intravenous administration of 4 hypophysiotropic releasing hormones (4RH test), followed by measurement of plasma concentrations of ACTH, GH, luteinizing hormone (LH), prolactin (PRL), and TSH. In the PH dogs this test was repeated after 4 and 12 weeks of thyroxine treatment.
Results: In 6 PH dogs, the basal TSH concentration was within the reference range. In the PH dogs, the TSH concentrations did not increase with the 4RH test. However, TSH concentrations increased significantly in the NTI dogs. Basal and stimulated GH and PRL concentrations indicated reversible hypersomatotropism and hyperprolactinemia in the PH dogs, but not in the NTI dogs. Basal and stimulated LH and ACTH concentrations did not differ between groups.
Conclusions and Clinical Importance: Dogs with spontaneous PH hypersecrete GH but have little or no TSH hypersecretion. Development of hyperprolactinemia (and possible galactorrhea) in dogs with PH seems to occur only in sexually intact bitches. In this group of dogs with NTI, basal and stimulated plasma adenohypophyseal hormone concentrations were not altered.     

Immunohistochemical study on ACTH cells and TSH cells of pituitary pars distails of morphine dependent male rats and its restoration after withdrawal

AIM: To investigate the change of adrenocorticotropic hormone (ACTH) cells and thyroid- stimulating hormone(wn) cells of pars distalls of pituitary gland of morphine dependent dependent rats and its restoration after withdrawal. METHODS: Morphine dependent model of male rats was made by subcutaneous injection of mor- phine and the adstinent model was made after withdrawal. Changes of ACTH cells and TSH cells of pars distails of pituitary gland were detected by immunohistochemistoy survey and image analysis. RESULTS: The intensity of positive staining and the numerical density of ACTH and TSH immunoreactive cells were weakened (P＜ 0.01), after withdrawal from morphine for a short time the changes would exist continuously. CONCLUSION: Morphine may give rise to disorder of endocrine of pituitary gland of male rats, which may incompletely restore after withdrawal for a short time.     

Seasonal and pulsatile dynamics of thyrotropin and leptin in mares maintained under a constant energy balance

The objective of this study was to determine if seasonal and/or pulsatile variations occur in plasma concentrations of thyrotropin (TSH) and leptin in mares while maintaining a constant energy balance. Blood samples were collected every 20 min during a 24 h period in winter and again in summer from six Quarter Horse type mares. Plasma concentrations of TSH, leptin, and T₄ were determined by radioimmunoassay. No differences were observed in body weight between winter (388.1 ± 12.5 kg) and summer (406.2 ± 12.5 kg; P = 0.11). Plasma concentrations of TSH were greater in the summer (2.80 ± 0.07 ng/ml) when compared to winter (0.97 ± 0.07 ng/ml; P < 0.001). Pulse frequency of TSH was not different between winter (6.17 ± 0.78 pulses/24 h) and summer (5.33 ± 0.78 pulses/24 h; P = 0.49). Mean TSH pulse amplitude, pulse area, and area under the curve were all greater in summer compared to winter (3.11 ± 0.10 ng/ml versus 1.20 ± 0.10 ng/ml, 24.86 ± 0.10 ng/ml min versus 13.46 ± 1.90 ng/ml min, 3936 ± 72.93 ng/ml versus 1284 ± 72.93 ng/ml, respectively; P < 0.01). Mean concentrations of leptin were greater in summer (2.48 ± 0.17 ng/ml) compared to winter (0.65 ± 0.17 ng/ml; P < 0.001). Pulsatile secretion patterns of leptin were not observed in any horses during experimentation. Mean concentrations of T₄ were greater in winter (20.3 ± 0.4 ng/ml) compared to summer (18.2 ± 0.4 ng/ml; P < 0.001). These seasonal differences between winter and summer provide evidence of possible seasonal regulation of TSH and leptin.