ÇİĞDEM ALTINSAAT, Aykut Göktürk ÜNER, Nesrin SULU

Seasonal changes of serum leptin, triiodothyronine, and thyroxine levels in Arabian mares

Bu çalışmanın amacı Arap atlarında serum leptin, triiodotronin ve tiroksin seviyelerinin mevsimsel olarak değişimleri ile troid hormonlarının leptin seviyeleri üzerine etkisinin olup olmadığını belirlemektir. Kan örnekleri üreme döneminde ve üremenin olmadığı dönemde 16 Arap kısrağından vena jugularis yolu ile toplandı. Hormon seviyeleri radioimmunoassay yolu ile ölçüldü. Ortalama leptin seviyeleri üreme döneminde (2.84±0.19 ng/mL) üremenin olmadığı dönemden (1.91±0.16 ng/mL) daha yüksekti. Triiodotronin seviyeleri üremenin olmadığı dönemde (221±31.61 ng/dL) üreme döneminden (105±5.91 ng/dL) daha yüksekti. Üreme döneminde (30.30±1.83 nmol/L) ve üremenin olmadığı dönemde (36.34±4.28 nmol/L) tiroksin seviyelerinde fark gözlemlenmedi. Üreme döneminde leptin ile tiriiodotronin arasında ilişki olmasına rağmen (r= 0.860, P0.05). Üremenin olmadığı dönemde tiriiodotronin ve tiroksin arasında anlamlı bir ilişki vardı (r= 0.791, P

Anahtar Kelimeler:

tiroksin, Arap atı, vücut ağırlığı, at, leptin, kısrak, mevsimsel değişimler, triiyodotironin

Arap kısraklarında serum leptin, triiodotronin ve tiroksin seviyelerinin mevsimsel değişimleri

The objective of study was to determine seasonal changes of leptin, triiodothyronine, and thyroxine and to determine whether an effect of thyroid hormones on leptin levels in Arabian mare. Blood samples were collected via jugular venipuncture from 16 Arabian mares during breeding and non-breeding season. Hormone concentrations were measured by radioimmunoassay. Mean concentrations of leptin were greater in breeding season (2.84±0.19 ng/mL) than non-breeding season (1.91±0.16 ng/mL). Mean concentrations of triiodothyronine were greater in non-breeding season (221±31.61 ng/dL) than breeding season (105±5.91 ng/dL). No differences in thyroxine levels were observed between breeding (30.30±1.83 nmol/L) and nonbreeding season (36.34±4.28 nmol/L). A significant correlation between leptin and triiodothyronine existed for breeding season (r= 0.860, P<0.01) but not for non-breeding season (r= 0.356, P>0.05). In non-breeding season, there was a significant correlation between triiodothyronine and thyroxine (r= 0.791, P<0.01). These seasonal differences and relationships between leptin, triiodothyronine, and thyroxine suggest that secretion of leptin may be affected by thyroid function in Arabian mares.

Keywords:

thyroxine, Arab, body weight, horses, leptin, mares, seasonal variation, triiodothyronine,

PDF

___

Stephens TW, Basinski M, Bristow PK, Bue-Valleskey JM, Burgett SG, Craft L, Hale J, Hoffmann J, Hsiung HM, Kriauciunas A, MacKellar W, Rosteck JrPR, Schoner B, Smith D, Tinsley FC, Zhang XY, Heiman M: The role of neuropeptide Y in the antiobesity action of the obese gene product. Nature, 377, 530-532, 1995.
Brunetti L, Orlando G, Michelotto B, Ragazzoni E, Vacca M: Leptin stimulates prostaglandin E2 and F2-alpha, but not nitric oxide production in neonatal rat hypothalamus. Eur J Pharmacol, 369, 299-304, 1999.
Houseknecht KL, Baile CA, Matteri RL, Spurlock ME: The biology of leptin: A review. J Anim Sci, 76, 1405-1420, 1998. Gentry LR: Body Condition, Leptin, and Reproductive Characteristics of Horses. Ph.D. Dissertation, Louisiana State University, Baton Rouge, LA., 2001.
Henneke DR, Potter GD, Kreider JL, Yeates BF: Relationship between condition score, physical measurements and body fat percentage in mares. Equine Vet J, 15, 371-376, 1983.
Buff PR, Dodds AC, Morrison CD, Whitley NC, McFadin EL, Daniel JA, Djiane J, Keisler DH: Leptin in horses: tissue localization and relationship between peripheral concentrations of leptin and body condition. J Anim Sci, 80, 2942-2948, 2002.
Gentry LR, Thompson DLJr, Gentry GTJr, Davis KA, Godke RA, Cartmill JA: The relationship between body condition, leptin, and reproductive and hormonal characteristics of mares during the seasonal anovulatory period. J Anim Sci, 80, 2695-2703, 2002.
Buff PR, Morrison CD, Ganjam VK, Keisler DH: Effects of short-term feed deprivation and melatonin implants on circadian patterns of leptin in the horse. J Anim Sci, 83, 1023-1032, 2005.
Buff PR, Messer NT, Cogswell AM, Johnson PJ, Keisler DH, Ganjam VK: Seasonal and pulsatile dynamics of thyrotropin and leptin in mares maintained under a constant energy balance. Domest Anim Endocrinol, 33,430-436, 2007.
Fitzgerald BP, McManus CJ: Photoperiodic versus metabolic signals as determinants of seasonal anestrus in the mare. Biol Reprod, 63, 335-340, 2000.
Gentry LR, Thompson DLJr, Gentry GTJr, Davis KA, Godke RA: High versus low body condition in mares: Interactions with responses to somatotropin, GnRH analog, and dexamethasone. J Anim Sci, 80, 3277-3285,2002.
Cartmill JA: Leptin in Horses: Influences of Body Condition, Gender, Insulin Insensitivity, Feeding, and Dexamethasone. Ph.D. Dissertation, Louisiana State University, Animal Science (Animal, Dairy, & Poultry Sciences) Baton Rouge, LA., 2004.
Forrest D: The erbA/thyroid hormone receptor genes in development of the central nervous system. Semin Cancer Biol, 5, 167-176, 1994.
Freake HC, Oppenheimer JH: Thermogenesis and thyroid function. Annu Rev Nutr, 15, 263-291, 1995.
Castracane VD, Henson MC: Leptin and thyroid function. In, Considine, RV (Ed): Leptin-Leptin and Other Endocrine Systems. 102-124, Springer, NY, USA, 2006. e-ISBN- 10:0-387-31416-4.
Cartmill JA, Thompson DLJr, Gentry LR, Pruett HE, Johnson CA: Effects of dexamethasone, glucose infusion, adrenocorticotropin, and propylthiouracil on plasma leptin concentrations in horses. Domest Anim Endocrinol, 24, 1-14, 2003.
Kautzky-Willer A, Ludwig C, Nowotny P, Roden A, Huemer C, Widhalm K, Vierhapper H, Waldhausl W, Roden M: Elevation of plasma leptin concentrations in obese hyperinsulinaemic hypothyroidism before and after treatment. Eur J Clin Invest, 29, 395-403, 1999.
Syed MA, Thompson MP, Pachucki J, Burmeister LA: The effect of thyroid hormone on size of fat depots accounts for most of the changes in leptin mRNA and serum levels in the rat. Thyroid, 9, 503-512, 1999.
Zimmermann-Belsing T, Brabant G, Holst JJ, Feldt- Rasmussen U: Circulating leptin and thyroid dysfunction. Eur J Endocrinol, 149, 257-271, 2003.
Rousseau K, Atcha Z, Cagampang FR, Le Rouzic P, Stirland JA, Ivanov TR, Ebling FJ, Klingenspor M, Loudon AS: Photoperiodic regulation of leptin resistance in the seasonally breeding Siberian hamster (Phodopus sungorus). Endocrinology, 143, 3083-3095, 2002.
Zhao ZJ, Wang DH: Short photoperiod influences energy intake and serum leptin level in Brandt's voles (Microtus brandtii). Horm Behav, 49, 463-469, 2006.
Li XS, Wang DH: Photoperiod and temperature can regulate body mass, serum leptin concentration, and uncoupling protein 1 in Brandt's voles (Lasiopodomys brandtii) and Mongolian gerbils (Meriones unguiculatus). Physiol Biochem Zool, 80, 326-334, 2007.
Soppela P, Saarela S, Heiskari U, Nieminen M: The effects of wintertime undernutrition on plasma leptin and insulin levels in an arctic ruminant, the reindeer. Comp Biochem Physiol B Biochem Mol Biol, 149, 613-621, 2008.
Johnson MS, Onorato DP, Gower BA, Nagy TR: Weight change affects serum leptin and corticosterone in the collared lemming. Gen Comp Endocrinol, 136, 30-36, 2004.
Bernabucci U, Basirico L, Lacetera N, Morera P, Ronchi B, Accorsi PA, Seren E, Nardone A: Photoperiod affects gene expression of leptin and leptin receptors in adipose tissue from lactating dairy cows. J Dairy Sci, 89, 4678- 4686, 2006.
Johnson AL: Serum concentrations of prolactin, thyroxine and triiodothyronine relative to season and the estrous cycle in the mare. J Anim Sci, 62, 1012-1020, 1986.
Flisinska-Bojanowska A, Komosa M, Gill J: Influence of pregnancy on diurnal and seasonal changes in cortisol, T3 and T4 levels in the mare blood serum. Comp Biochem Physiol A, 98, 23-30, 1991.
Guyton AC, Hall JE: Textbook of Medical Physiology. W.B. Saunders, Philadelphia, PA, USA, 897-906, 1986.
Cartmill JA, Thompson DLJr, Storer WA, Gentry LR, Huff NK: Endocrine responses in mares and geldings with high body condition scores grouped by high vs. low resting leptin concentrations. J Anim Sci, 81, 2311-2321,2003.
Escobar-Morreale HF, Escobar del Rey F, Morreale de Escobar G: Thyroid hormones influence serum leptin concentrations in the rat. Endocrinology, 138, 4485-4488,1997.
Pinkney JH, Goodrick SJ, Katz J, Johnson AB, Lightman SL, Coppack SW, Mohamed-Ali V: Leptin and the pituitary-thyroid axis: A comparative study in lean, obese, hypothyroid and hyperthyroid subjects. Clin Endocrinol (Oxf), 49, 583–588, 1998.