Decreased ACTH secretion during prolonged transportation stress is associated with reduced pituitary responsiveness to tropic hormone stimulation in cattle

The present study examined the effect of transportation stress on hypothalamic–pituitary–adrenal axis responsiveness to tropic hormone stimulation and on abundance of corticotropin releasing factor (CRF) receptor R1 (CRFR1) and arginine vasopressin (AVP) receptor V3 (V3) mRNAs in the anterior pituitary (AP) of cattle. Holstein steers were transported for 10 h or used as non-transported controls (NTC). Blood samples were collected at start of transportation and every 1–2 h thereafter. To test AP responsiveness to tropic hormones, animals were challenged (i.v.) with CRF (0.5 μg/kg), AVP (1 μg/kg) or CRF plus AVP immediately after end of transportation and blood samples collected every 30 min for 3 h. The AP of animals transported for 0, 4 or 10 h were harvested for mRNA analyses. Plasma ACTH in transported animals increased within 1 h and remained elevated for 6 and 8 h versus NTC and 0 h values, respectively. Plasma concentrations of cortisol increased in response to transportation and remained elevated throughout the transport period. Injection of CRF or AVP to NTC animals increased plasma ACTH, but ACTH secretion in response to CRF or AVP was dramatically reduced in transported animals. ACTH secretion following co-injection of CRF and AVP tended to be less in transported animals, but was almost 100% greater than when secretagogues were administered separately. Despite decreased AP responsiveness to CRF and AVP, AP CRFR1 and V3 mRNAs were increased after 10 h transportation. Results indicate decreased AP responsiveness to CRF and AVP may regulate duration of ACTH secretion in response to transportation stress in cattle.     

Synthetic adrenocorticotropic hormone stimulation tests in healthy neonatal foals

BACKGROUND: Cosyntropin (adrenocorticotropic hormone [ACTH]) stimulation tests are used to evaluate adrenal function. Low-dose ACTH stimulation tests are the most accurate method for diagnosing relative adrenal insufficiency in critically ill humans but have not been evaluated in foals. HYPOTHESIS: Peak serum cortisol concentrations in healthy foals will not be significantly different after intravenous administration of 1, 10, 100, and 250 microg of cosyntropin. ANIMALS: 14 healthy neonatal foals, 3-4 days of age. METHODS: A randomized cross-over model was used in which cosyntropin (1, 10, 100, or 250 microg) was administered intravenously on days 3 and 4 of life. Blood samples were collected before and 30, 60, 90, 120, and 150 minutes after administration of cosyntropin for determination of serum cortisol concentration. RESULTS: Serum cortisol concentrations did not significantly increase after administration of 1 microg of cosyntropin. Cortisol concentration peaked 30 minutes after administration of 10 microg of cosyntropin and 90 minutes after 100 and 250 microg of cosyntropin. There was no relationship between cosyntropin dose and serum cortisol concentration at 30 minutes. Compared with the 10-microg dose, 100 and 250 microg of cosyntropin induced significantly greater cortisol concentrations at 90 minutes, at which point the 10-microg cosyntropin-dose cortisol values were indistinguishable from baseline. There was no significant difference in the area under the cortisol concentration curve between the 100- and 250-microg doses. No effect of day of testing or foal weight on peak cortisol concentration was detected. CONCLUSIONS AND CLINICAL IMPORTANCE: The results of this study suggest that 10- and 100-microg doses of cosyntropin would be appropriate for evaluating adrenal function in neonatal foals.     

Pharmacopuncture Versus Acepromazine in Stress Responses of Horses During Road Transport

Acupuncture has been shown to have the beneficial effect of reducing stress responses in animals and humans. Pharmacopuncture is the injection of subclinical doses of drugs into acupoints to give therapeutic results without side effects. This study compared the effects of injecting the usual dose of acepromazine (ACP; 0.1 mg/kg, intramuscularly [I.M.]) with those of pharmacopuncture (1/10 ACP dose at the governing vessel 1 [GV 1] acupoint) on the stress responses of healthy horses undergoing road transport for 2.5 hours. Four different treatments were applied immediately before loading, with 8 animals/treatment: injection of saline or ACP (0.1 mg/kg, I.M.) at the base of the neck; and injection of saline or 1/10 ACP (0.01 mg/kg) at the GV 1 acupoint. The road transport increased heart rate (HR), respiratory rate, body temperature, and serum cortisol of the untreated horses (injected with saline at the base of the neck). Pharmacopuncture at GV 1 reduced the average HR and transport-induced increase in HR at unloading, without changing the other variables. On the other hand, ACP (0.1 mg/kg) produced significant sedation and reduced the transport-induced increase in respiratory rate but without preventing the stress-induced increase of cortisol. Other acupuncture points and drugs should be tested to verify the beneficial effect of this therapy to reduce stress in horses during road transport.     

Effects of anaesthesia with MS-222, clove oil and CO2 on feed intake and plasma cortisol in steelhead trout (Oncorhynchus mykiss)

We examined the effects tricaine methanesulfonate (MS-222), clove oil and CO₂ on feed intake and cortisol response in steelhead trout, Oncorhynchus mykiss. Even though a body of literature exists about the effects of different anaesthetics on fish, no comparative information seems to be available about their effects on feed intake after anaesthesia, which would be important to know especially in aquaculture research. We anaesthetised juvenile steelhead trout with these three anaesthetics, and then sampled them 4, 24 and 48 h later. Fish in all groups ate relatively well already 4 h after anaesthesia. However, feed intake in fish treated with clove oil or MS-222 was lower than in the controls. There were no differences in feed intake among anaesthetised groups. Plasma cortisol concentrations were elevated 48 h after anaesthetisation, but the treatment means were equal throughout the experiment. Our results support previous findings that clove oil is a reasonable alternative to MS-222.     

Altered Serum Thyrotropin Concentrations in Dogs with Primary Hypoadrenocorticism before and during Treatment

Background

Thyrotropin (TSH) can be increased in humans with primary hypoadrenocorticism (HA) before glucocorticoid treatment. Increase in TSH is a typical finding of primary hypothyroidism and both diseases can occur concurrently (Schmidt's syndrome); therefore, care must be taken in assessing thyroid function in untreated human patients with HA.

Objective

Evaluate whether alterations in cTSH can be observed in dogs with HA in absence of primary hypothyroidism.

Animals

Thirty dogs with newly diagnosed HA, and 30 dogs in which HA was suspected but excluded based on a normal ACTH stimulation test (controls) were prospectively enrolled.

Methods

cTSH and T4 concentrations were determined in all dogs and at selected time points during treatment (prednisolone, fludrocortisone, or DOCP) in dogs with HA.

Results

cTSH concentrations ranged from 0.01 to 2.6 ng/mL (median 0.29) and were increased in 11/30 dogs with HA; values in controls were all within the reference interval (range: 0.01–0.2 ng/dL; median 0.06). There was no difference in T4 between dogs with increased cTSH (T4 range 1.0‐2.1; median 1.3 μg/dL) compared to those with normal cTSH (T4 range 0.5‐3.4, median 1.4 μg/dL; P=0.69) and controls (T4 range 0.3‐3.8, median 1.8 μg/dL; P=0.35). After starting treatment, cTSH normalized after 2–4 weeks in 9 dogs and after 3 and 4 months in 2 without thyroxine supplementation.

Conclusions and Clinical Relevance

Evaluation of thyroid function in untreated dogs with HA can lead to misdiagnosis of hypothyroidism; treatment with glucocorticoids for up to 4 months can be necessary to normalize cTSH.     

盐度胁迫对大鳞鲃抗氧化酶和血清皮质醇的影响

为阐明盐度胁迫对大鳞鲃(Luciobarbus capito)肝、肾和鳃组织抗氧化系统及血清皮质醇的影响,本研究设置4个NaCl盐度组(3、6、9和12 g/L)和1个淡水对照组,检测分析了不同盐度胁迫下曝露3、6、12、24、48、96 h和7 d大鳞鲃肝、肾和鳃组织中酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、谷胱甘肽过氧化物酶(GSH-Px)的活性和丙二醛(MDA)含量的变化,以及血清中皮质醇浓度的变化。结果显示,在相同盐度胁迫下,大鳞鲃的肝、肾和鳃组织中ACP、AKP、GSH-Px抗氧化酶的活力、MDA含量以及血清皮质醇含量随胁迫时间的延长均呈先上升后下降、随后趋于稳定的变化趋势,在胁迫开始24 h内各指标达到峰值,并在48 h开始逐渐趋于平稳;胁迫初期,相同曝露时间,大鳞鲃的肝、肾和鳃组织中3种抗氧化酶活力、MDA含量及血清皮质醇含量均与盐度呈显著正相关性。大鳞鲃在盐度胁迫过程中,ACP、AKP活力和MDA含量在肾组织的范围分别为1.42~2.15 U/g prot、1.01~1.87金氏单位/g prot和13.05~57.27 nmol/mg prot;肝组织中分别为1.27~1.96 U/g prot、0.31~0.86金氏单位/g prot和17.02~55.98 nmol/mg prot;鳃组织则为0.98~1.96 U/g prot、0.13~0.84金氏单位/g prot和8.33~53.93 nmol/mg prot,肾组织中ACP、AKP活力和MDA含量均高于肝、鳃组织;而GSH-Px的活力在肝、肾和鳃组织的范围分别为44.41~114.77、16.52~67.59和9.07~48.00活力单位,肝组织中GSH-Px活力显著高于肾和鳃组织。此外,血清皮质醇在盐度胁迫过程中的含量变化范围为197.00~355.50 ng/L。综上所述,在12 g/L的高盐胁迫下大鳞鲃通过自身调节,各项指标仍可恢复正常,表明其对盐度环境有较强的适应能力。