BERTONI, G

BLUM, J

BRUCKMAIER, R

Gubbiotti, Alessandra

Lefever, Steve

Senepart, Lukas

TREVESI, E

WINTERS, K

Undetermined

Ghent University Academic Bibliography

01020304050-96 -24 0 2 4 6 8 10 12 14 24 48 72 144 216hours relative to infectionng/mlThyroid hormones and cortisol in lactating cows after intramammary LPS or Escherichia coli administrationL. Senepart1*, K. Winters1, A. Gubbiotti2, S. Lefever1, R.M. Bruckmaier3, J.W. Blum3, G. Bertoni2, E. Trevisi2, C. Burvenich1.1 Milk Secretion and Mastitis Research Center (MMRC), Faculty of Veterinary Medicine, Ghent University, Belgium2 Inst. of Zootechnics, Fac. of Agriculture, Università Cattolica S. Cuore, Piacenza, Italy3 Division of Nutritional Pathology, Faculty of Veterinary Medicine, University of Berne, Switzerland*Corresponding Author: Lukas.Senepart@UGent.beIntroductionThe incidence of coliform mastitis is highest around parturitionand during early lactation3. During growth and destruction of E. coli, lipopolysaccharides (LPS) are released in great amounts. Administration of LPS an E. coli mastitis share the same clinical signs and both mediate the release of inflammatory cytokines4. In this study, we compared the effects on endocrine changes using two strategies (i.e. challenge with E. coli and LPS) to induce mastitis. Materials and MethodsTwelve healthy East Flemisch Red Pied cows were accepted in the study. Six cows were infected with 1*104 cfu/quarter of E. colistrain P4:O32 (A.Hill, Compton, U.K.) while the other six cows were infused with 500 µg/quarter of endotoxin (LPS) from E. colistrain O111:B4, in the left front and rear quarters. The cows were  transfered in individual tie-stalls one week before the challenge. They were fed with approximately 8 kg of concentrates, and were allowed to eat hay and drink water ad libitum. Blood samples were collected daily, 1 hour after morning milking (i.e. 1,5 hours after the morning meal) on day -1, +1, +2, +3, +6 and +9. On day 0, blood samples were collected immediately before infection (0 hours) and every 2 hours from 2 up to 14 hours after inoculation. Plasma levels of cortisol were analysed using the methods of Blum et al.2; T4, T3 and rT3 were analysed using the methods described by Bertoni et al.1. Data were analyzed with a two way ANOVA, including group and time in the model, using the statistical analysis program package Statistix (Analytical Software, Tallahassee, FL, USA).Results• T3 shows an increase in both groups and this increase was more pronounced after E. coli infection then after LPS infusion. 24 hours post infection however, an all time low in T3 (and T4) is seen.• The rT3 profile shows a clear rise in both groups. The rise in rT3 occurs later in the E. coli group. • Plasma cortisol levels increases in a spectacular way in both groups. The increase occurs later and is more pronounced in the E. coli group compared to the LPS group. DiscussionIntramammary infusion of LPS or E. coli infection induced a release of cortisol and rT3 in blood plasma of cows. The decrease in T3 and T4 seen around 18–24 hours post inoculation seems to be correlated with the increase of rT3 in the same period. This may be a result of the conversion of T3 and T4 to rT3 in the peripheral tissues. This inactivation of thyroid hormones may be a countermeasure to avoid hyperthermia after disease. Cortisol may have role in the conversion of T3 and T4 to rT3 which would explain its rise5. The changes in concentration of the parameters were induced faster after i.mam.LPS then compared with E. coli administration. LPS can directly activate macrophages and/or epithelium in the mammary gland to release inflammatory cytokines through binding to the CD-14 receptor4. During E. coli mastitis, LPS first has to be released by bacteria before cells can be activated, so the onset of the changes occurs later. However, its effects appeared more pronounced thanLPS infusion because cortisol remained higher for a longer time.References1. Bertoni et al. (1983). Considerazioni e ricerche sui rapporti fra lattazione, metabolismo energetico ed attività tiroidea. Zoot. Nutr. Anim. 9:19-30.2. Blum et al. (1996). Endocrine, metabolic and hematological changes associated with reduced growth performance during chronic pneumonia in calves: A case study. Deut. Tier. Wochen. 103(4):115-116.3. Burvenich et al. (2003). Severity of E. coli mastitis is mainly determined by cow factors.  Vet. Res. 34(5):521-564.4. Paape et al. (2003). The bovine neutrophil: Structure and function in blood and milk.  Vet Res. 34(5):597-627. 5. Decuypere et al. (1983) Effects of glucocorticoids on circulating concentrations of thyroxine (T4) and triiodothyronine (T3) on peripheral monodeiodination in pre- and post-hatching chickens. Horm. Metab. Res. 15(5):233-6. 00,511,522,5-96 -24 0 2 4 6 8 10 12 14 24 48 72 144 216hours relative to infectionng/ml²3,5,3' Triiodothyronine (T3)00,10,20,30,40,50,6-24 0 2 4 6 8 10 12 14 24 48 72hours relative to infectionng/ml3,3',5' Triiodothyronine (rT3)01020304050607080-96 -24 0 2 4 6 8 10 12 14 16 18 24 48 72 144 216hours relative to infectionng/ml3,5,3',5' Tetraiodothyronine (T4)CortisolFigure 1: Mean changes in T3 and T4 in bloodplasma of healthy cows after i.mam. E. coli LPS(500 µg/quarter; blue areas) or i.m. infection with E. coli (1*104 cfu/quarter; purple areas).Figure 2: Mean changes in rT3 and cortisol in bloodplasma of healthy cows after i.mam. E. coli LPS(500 µg/quarter; blue areas) or i.m. infection with E. coli (1*104 cfu/quarter; purple areas).

Thyroid hormones and cortisol in lactating cows after intramammary LPS administration

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Thyroid hormones and cortisol in lactating cows after intramammary LPS administration

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