Somatotrophin increases thyroxine-5′-monodeiodinase activity in lactating mammary tissue of the cow

Capuco, Anthony; Keys, J.E.; Smith, J. J.

doi:10.1677/joe.0.1210205

Cited by 50 publications

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“…As men tioned, we favor the hypothesis that GH therapy pri marily acts to stimulate the peripheral deiodination of T4 to T4. an effect which has also been demonstrated in other species [21,22], If this holds true, it could also explain the decreased T4 levels and radioiodine uptake and the blunted TSH response to TRH observed in other studies assuming a feedback inhibition by the elevated (normal ized) T3 levels. That GH therapy per se should induce hypothyroidism would also be difficult to understand from a teleological point of view, and is also incompatible with reported GH effects such as increased energy expen diture, increased resting-heart rate and lowering of serum cholesterol.…”

Section: Christiansensupporting

confidence: 61%

Thyroid Function during Growth Hormone Therapy

et al. 1992

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Administration of growth hormone (GH) in GH-deficient patients has been reported to cause a variety of perturbations in thyroid function. Reports range from decreased sensitivity of thyrotropin (TSH) to thyrotropin-releasing hormone (TRH) stimulation and induction of hypothyroidism to increased energy expenditure and enhanced peripheral thyroxine (T₄) to triiodothyronine (T₃) conversion. Some of the diversities may relate to the fact that earlier studies were uncontrolled case reports, which furthermore employed pituitary GH preparations, which may have been contaminated with TSH. A confounding variable in terms of incipient TSH insufficiency in some patients may also have been present. Data from a placebo-controlled crossover study of 4-months GH therapy in GH-deficient adults, some of whom were on ongoing T₄ substitution, revealed that the most prominent effect on thyroid function was increased peripheral T₄ to T₃ conversion without significantly affecting TSH levels or secretion from the thyroid gland. It was furthermore observed that T3 levels during placebo were significantly decreased compared to an untreated healthy control group. Comparable findings have been made in a controlled study of 6-months GH therapy in adult-onset GH-deficient patients. More recent data suggest that these effects prevail after long-term (16 months) therapy. Similar findings have also been reported in healthy subjects receiving pharmacological GH doses. It is likely that this effect is not caused by GH per se inasmuch as reduced T₄ to T₃ conversion is a common observation in catabolic states with concomitant GH hypersecretion. It remains to be shown whether insulin-like growth factor I (IGF-I) stimulates peripheral deiodination.

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Section: Christiansensupporting

confidence: 61%

Thyroid Function during Growth Hormone Therapy

et al. 1992

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“…The decrease in T 4 : T 3 ratio after the 5th week postpartum may be because of the higher conversion of T 4 to T 3 in the liver of cows with AOV. However, significant changes in peripheral tissue conversion of T 4 to T 3 may occur without a detectable change in serum T 3 or T 4 (Capuco et al, 1989).…”

Section: Discussionmentioning

confidence: 98%

Relationships between thyroid hormones and serum energy metabolites with different patterns of postpartum luteal activity in high-producing dairy cows

Kafi

Tamadon

Saeb

et al. 2012

Animal

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This study investigated the relationships of thyroid hormones, serum energy metabolites, reproductive parameters, milk yield and body condition score with the different patterns of postpartum luteal activity in the postpartum period. A total of 75 multiparous healthy (free of detectable reproductive disorders) Holstein dairy cows (mean peak milk yield 5 56.5 6 7.0 kg/day) were used in this study. Transrectal ultrasound scanning and blood sample collection were performed twice weekly. Serum concentrations of progesterone (P 4 ) were measured twice weekly and beta-hydroxybutyrate (BHBA), non-esterified fatty acids, thyroxine (T 4 ), 3,30,5-tri-iodothyronine (T 3 ), free thyroxine (fT 4 ) and free 3,30,5-tri-iodothyronine (fT 3 ) were measured every 2 weeks from the 1st to the 8th week postpartum. On the basis of the serum P 4 profile of the cows, 25 (33.4%) had normal luteal activity (NLA), whereas 30 (40%), 10 (13.3%), 6 (8%) and 4 (5.3%) had prolonged luteal phase (PLP), delayed first ovulation (DOV), anovulation (AOV) and short luteal phase, respectively. Serum T 4 concentrations in PLP cows were higher than that in NLA cows at the 3rd week postpartum and did not change during the period of study, whereas in the NLA cows the concentrations increased (P , 0.05). Further, the least square (LS) mean of serum fT 4 concentrations in the DOV and AOV cows were significantly lower than in the NLA cows during the study period (P , 0.05). In addition, the AOV cows had higher LS mean serum BHBA and T 4 concentrations than the NLA cows in early weeks postpartum (P , 0.05). In conclusion, the serum thyroid hormones' profile differs in high-producing dairy cows showing PLP, AOV and DOV in comparison with the postpartum NLA cows.Keywords: thyroid hormone, energy metabolite, luteal activity, high-producing dairy cow ImplicationsThis study investigated the relationships of thyroid hormones, serum energy metabolites, reproductive parameters, milk yield and body condition score with the different patterns of postpartum luteal activity in the postpartum period. The serum thyroid hormones' profile differs in high-producing dairy cows showing prolonged luteal phase, anovulation and delayed first ovulation in comparison with the cows with normal postpartum luteal activity. IntroductionHigh-yielding dairy cows have been selected to produce more milk, in large part through their ability to mobilize fat and muscle to support milk production in early lactation. This results in a loss of body condition score (BCS) and is associated with alterations in blood metabolites and hormone profiles, which in turn influence fertility (Pryce et al., 2001;Wathes et al., 2007). The nutritional status of cattle is communicated within the hypothalamic-pituitary-ovarian axis via metabolic hormones or blood metabolites or both (Butler, 2000). Previous studies have focused on the association between negative energy balance (NEB) postpartum and delayed onset of ovarian cyclicity, and hence poor fertility (Lucy, 2003;Patton et al., 2007;Wathes et al., 2007)....

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“…us, thyroid hormone status may influence feed intake, which subsequently affects IGF-I levels, and may modify IGF-I concentrations through effects on GH secretion or receptor levels. Administration of GH to lactating cows increased the activity of mammary 5'D twofold (Capuco et al, 1989), thus enhancing the metabolic priority of the udder (Kahl et al, 1995). Significant independent associations of serum T 4 with T 3 and IGF-I levels during the puerperium were found in two experiments involving 60 healthy cows .…”

Section: Basic Physiology Nutritional Factors Influencing Thyroid Fumentioning

confidence: 88%

Clinical endocrinology of thyroid gland function in ruminants

Huszenicza¹,

Kulcsár²,

Rudas³

2002

Vet. Med.

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After briefly introducing the basec steps in production and metabolism of thyroid hormones, the author gives an overview of nutritional, metabolic and disease related factors and endocrine interactions influencing thyroid gland function in ruminants, particularly in the postpartum dairy cow. Involvement of thyroid hormonal regulation of seasonal patterns of reproduction as well as ovarian endocrine function are discussed.Keywords: thyroxin; triiodothyronine; ovary; metabolism; ruminants Abbreviations: 5'D = 5'-deiodinase (syn.: outer-ring deiodinase); 5D = 5-deiodinase (syn.: inner-ring deiodinase); BHB = βOH-butyrate; E 2 = 17β-estradiol; FSH = follicle stimulating hormone; GH = growth hormone; GnRH = gonadotropin releasing hormone; hCG = human chorionic gonadotropin; IGF-I = insulin-like growth factor-I (syn.: somatomedin C); IL = interleukin; LH = luteinizing hormone; mRNA = messenger ribonucleic acid; NEB = negative energy balance; NEFA = non-esterified fatty acids; P 4 = progesterone; PVN = paraventricular nucleus of the hypothalamus; rT 3 = 3,3',5'-triiodothyronine (syn.: reverse-triiodothyronine); T 3 = 3,3',5-triiodothyronine; T 4 = thyroxine; TNFα = tumor necrosis factor-α; TRH = thyrotropin-releasing hormone; TSH = thyroid-stimulating hormone (syn.: thyrotropin)

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Somatotrophin increases thyroxine-5′-monodeiodinase activity in lactating mammary tissue of the cow

Cited by 50 publications

References 0 publications

Thyroid Function during Growth Hormone Therapy

Thyroid Function during Growth Hormone Therapy

Relationships between thyroid hormones and serum energy metabolites with different patterns of postpartum luteal activity in high-producing dairy cows

Clinical endocrinology of thyroid gland function in ruminants

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