Effect of 17β-estradiol on milk production, hormone secretion, and mammary gland gene expression in dairy cows
Bibliographic record
Abstract
Estradiol inhibits milk production in dairy cows. The present study evaluated the effect of 17β-estradiol (E2) injections on prolactin (PRL) secretion and the mammary gland response to this hormone. Eight mid-lactation cows were used in a crossover design. During each experimental period, the cows were injected daily with either E2 (2.5 mg) or soy oil (2.5 mL; control) for 7 d. For each period, blood and milk samples were collected from d -4 to 14 (relative to the first injection) to measure PRL, insulin-like growth factor-1, and cortisol concentrations. In addition, blood samples were collected during morning milking on d -4, 2, and 7 to determine the milking-induced PRL release. Mammary gland biopsies were collected on the last day of injections. Milk fat samples were collected from d 1 to 7 and on d 14. The mRNA levels of genes encoding proteins related to mammary activity (α-lactalbumin, β-casein, and acetyl-coenzyme A carboxylase), apoptosis (Bax, Bcl2, and caspase-3), PRL receptors (PRLR; long and short forms), signal transducer and activator of transcription 5 (STAT5A and STAT5B), and suppressors of cytokine signaling (SOCS2 and SOCS3) were evaluated by real-time reverse transcription PCR using RNA extracted from milk fat and mammary biopsies. Milk production was decreased moderately (about 9%) by E2 injections during the treatment period. Estradiol injections increased basal PRL levels in serum and milk but did not affect milking-induced PRL release. Estradiol injections increased the plasma concentration of insulin-like growth factor-1 but did not affect cortisol concentration during the treatment period. In mammary tissue, the expression of Bcl2 was downregulated, whereas that of STAT5A and B and the Bax:Bcl2 mRNA ratio was higher during E2 injections. The total STAT5 protein content in mammary tissue was elevated by E2 injections. We found no significant difference observed for the other genes in mammary tissue or milk fat. The present data do not support the contention that E2 injections inhibit milk production by interfering with PRL signaling, but enhanced basal PRL concentration and STAT5 gene expression in mammary tissue.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".