Abstract #M190

# M190
mRNA expression of 11bHSD1 and 17bHSD12 in adipose tissue of dairy cows with high and normal body condition score.
K. Schuh*1,2, S. Häussler1, C. Koch3, D. Frieten2, G. Dusel2, H. Sadri1, H. Sauerwein1, 1University of Bonn, Institute for Animal Science Physiology & Hygiene, Bonn, North Rhine-Westphalia, Germany, 2University of Applied Sciences Bingen, Animal Nutrition and Health, Bingen am Rhein, Rhineland Palatinate, Germany, 3Educational and Research Centre for Animal Husbandry, Hofgut Neumühle, Münchweiler a.d. Alsenz, Rhineland Palatinate, Germany.

Dairy cows have a huge potential to mobilize body fat reserves after parturition, depending on their body condition (BCS) before calving. Steroidogenic enzymes are expressed within adipose tissue (AT) and overexpression of these enzymes might lead to the increased release of locally metabolized steroids into the circulation, thus probably affecting the hormonal status of dairy cows. In the present study, we investigated the mRNA expression of 11b-hydroxysteroid dehydrogenase type 1 (11bHSD1) activating cortisone into cortisol, and 17b-hydroxysteroid dehydrogenases type 12 (17bHSD12), converting estrone into estradiol, in subcutaneous (sc)AT of dairy cows with moderate or excessive mobilization of body fat. German Holstein cows (n = 38) were preselected 15 weeks before calving and allocated to either a high (HBCS; BCS >3.75) or normal (NBCS; BCS <3.5) BCS-group. In addition, back fat thickness (BFT) of both groups was measured (HBCS: BFT >1.4; NBCS: BFT <1.2). Biopsies from scAT (tail head region) were sampled on d −49, 3, 21, and 84 relative to calving. The mRNA abundance of the target genes was assessed by qPCR and normalized by using the 4 most stable reference genes. Data were analyzed using the mixed-model procedure followed by Bonferroni correction (SPSS 21). Early grouping of the cows lead to the differences in BCS and BFT (P < 0.001) which were maintained throughout the whole study. Until d 84 after calving, HBCS cows lost twice as much BFT compared with NBCS cows (P ≤ 0.001). For both groups the peak mRNA abundance of 11bHSD1 was detected on d 3, while mRNA abundance of 17bHSD12 was highest on d −49, followed by an 86 and 81% decline on d 3 and 21 (P < 0.001), respectively, and increased again by 108% on d 84 compared with d 3 (P < 0.05). Moreover, 17bHSD12 mRNA abundance was 32% higher for HBCS cows on d −49 compared with NBCS cows (P < 0.01). Increased mRNA abundance of 11bHSD1 around parturition may indicate for the local activation of the stress hormone in scAT. Moreover, the mRNA expression of 17bHSD12 was affected by the BCS on d −49, suggesting a local conversion of estradiol in cows with higher fat depots before parturition.

Key Words: bovine adipose tissue, steroidogenic enzyme, mRNA abundance