Effect of alpha-tocopherol deprivation on the involution of mammary gland in sheep.
The objective of this study was to investigate the effect of alpha-tocopherol deprivation on mammary gland involution and apoptosis in sheep. Two groups of four single lamb ewes were used. The control group received 100 mg/d of RRR-alpha-tocopherol supplementation and the experimental group received no vitamin E supplementation. After 3 mo of suckling, ewes were dried off, and blood samples from the jugular vein and tissue biopsies from the mammary gland were collected at d 1, 3, 5, and 8 after dry-off. The experimental group had lower plasma concentrations of alpha-tocopherol (1.8 vs. 4.2 micromol/L), lower glutathione peroxidase activity in erythrocytes, and higher concentration of malondialdehyde in plasma than the control group. Immunohistochemical analysis of tissue samples resulted in marked differences of bcl-2 and bax protein expressions during involution and between groups. The bax expression was decreased by alpha-tocopherol deprivation at 1, 3, and 5 d, but not at 8 d, while the bcl-2 score was higher only at 8 d (1.5 vs. 0.0 for experimental and control groups, respectively). As a result, the bcl-2 to bax ratios were increased for the experimental group at 1 and 8 d. During involution, apoptotic counts increased (from 0.12 to 4.06%), but no effects were detected in relation to bcl-2 to bax ratio and alpha-tocopherol. These results indicate that alpha-tocopherol can control bcl-2 expression, but not apoptosis in cells of the mammary gland during involution.
Colitti
M
M
Department of Animal Production Sciences, Faculty of Veterinary Medicine, University of Udine, Italy. monica.colitti@dspa.uniud.it
Stradaioli
G
G
Stefanon
B
B
D000818:Animals; D017209:Apoptosis; D001707:Biopsy, Needle / Q000662:veterinary; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D005260:Female; D005979:Glutathione Peroxidase / Q000032:analysis / Q000097:blood; D006454:Hemoglobins / Q000032:analysis; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling / Q000662:veterinary; D008315:Malondialdehyde / Q000032:analysis / Q000097:blood; D008321:Mammary Glands, Animal / Q000503:physiopathology*; D018384:Oxidative Stress; D011518:Proto-Oncogene Proteins / Q000032:analysis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D012756:Sheep; D012757:Sheep Diseases / Q000503:physiopathology*; D014810:Vitamin E / Q000032:analysis / Q000097:blood; D014811:Vitamin E Deficiency / Q000503:physiopathology / Q000662:veterinary*; D051028:bcl-2-Associated X Protein
D006454:Hemoglobins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D014810:Vitamin E; D008315:Malondialdehyde; D005979:Glutathione Peroxidase