Conjugated linoleic acid trans-10, cis-12 increases the expression of genes from cell cycle progression and cis-9, trans-11 stimulates apoptotic genes in different mammary tumor explants of female dogs.

BACKGROUND: The conjugated linoleic acid (CLA) isomer cis-9, trans-11 is an anticarcinogen that inhibits cell proliferation and/or induces apoptosis of tumor cells. The objective of this study was to evaluate the expression of genes responsible for cell cycle regulation and apoptosis in tumor explants of mammary anaplastic carcinoma (AC) and mammary tubulopapillary carcinoma (TC) cultured in vitro with the CLA isomers cis-9, trans-11 and trans-10, cis-12. METHODS: In this study we used mammary explants from two adult female dogs that revealed two types of malignant tumors: (a) anaplastic mammary carcinoma (AC) and (b) mammary tubulopapillary carcinoma (TC). The explants (n = 6 per treatment) had an average weight of 80.0 ± 2.0 mg and were cultured for 24 h in 35 mm culture plates under the following treatments: (a) Control: Culture medium + fatty acid free bovine serum albumin (BSA); (b) Culture medium + cis-9, trans-11 CLA (75 µM) diluted with fatty acid free bovine serum albumin (BSA), and; (c) Culture medium + trans-10, cis-12 CLA (75 µM) diluted with fatty acid free bovine serum albumin (BSA). After that, total RNA was extracted, complementary DNA was synthesized (cDNA), and quantitative analysis by real-time polymerase chain reaction (RT-qPCR) was conducted. Data were analyzed using the MIXED procedure of SAS. RESULTS: Compared with the Control, the CLA trans-10, cis-12 treatment decreased expression of the gene encoding the p53 by 20% (P = 0.02), Caspase-3 by 25% (P = 0.06) and Bax by 51% (P = 0.001) in AC. The CLA cis-9, trans-11 increased the gene expression of proapoptotic protein Bax in TC by 68% (P = 0.01), but increased the expression of the antiapoptotic Bcl2 gene in AC by 72% (P = 0.006). CONCLUSION: The CLA cis-9, trans-11 stimulates apoptotic genes in mammary tubulopapillary carcinoma, but has a contrary effect on the anaplastic carcinoma, and the CLA trans-10, cis-12 stimulates cell cycle progression genes and may have an antiapoptotic effect, mainly in mammary anaplastic carcinoma.

Trans-10, cis-12 conjugated linoleic acid reduces milk fat content and lipogenic gene expression in the mammary gland of sows without altering litter performance.

Trans-10, cis-12 conjugated linoleic acid (CLA) decreases milk fat synthesis in lactating sows and involves, at least in part, the down-regulation of lipogenic genes. The objective was to evaluate the effect of CLA on milk composition and lipogenic gene expression. Twenty multiparous sows were randomly assigned to one of the two treatments for 18 d (from day 7 to day 25 of lactation): (1) control (no CLA added) and (2) 1 % of CLA mixed into the ration. CLA treatment decreased milk fat and protein content by 20 % (P = 0·004) and 11 % (P = 0·0001), respectively. However, piglet weight did not differ between treatments (P = 0·60). Dietary CLA increased the concentration of SFA in milk fat by 16 % (P < 0·0001) and decreased MUFA by 17·6 % (P < 0·0001). In the mammary gland, CLA reduced gene expression of acetyl-CoA carboxylase-α by 37 % (P = 0·003), fatty acid synthase by 64 % (P = 0·002), stearoyl-CoA desaturase 1 by 52 % (P = 0·003), lipoprotein lipase by 26 % (P = 0·03), acyl glycerol phosphate acyltransferase 6 by 15 % (P = 0·02) and diacylglycerol acyltransferase 1 by 27 % (P = 0·02), whereas the expression of fatty acid binding protein 3 was not altered by CLA treatment (P = 0·09). Mammary expression of casein-ß and α-lactalbumin was reduced by CLA by 68 % (P = 0·0004) and 62 % (P = 0·005), respectively. Additionally, CLA had no effect on the expression of lipogenic genes evaluated in adipose tissue. In summary, CLA reduced milk fat content without negatively affecting litter performance and it affected mammary expression of genes involved in all lipogenic pathways studied.

Transient reductions in milk fat synthesis and their association with the ruminal and metabolic profile in dairy cows fed high-starch, low-fat diets.

Sub-acute ruminal acidosis (SARA) is sometimes observed along with reduced milk fat synthesis. Inconsistent responses may be explained by dietary fat levels. Twelve ruminally cannulated cows were used in a Latin square design investigating the timing of metabolic and milk fat changes during Induction and Recovery from SARA by altering starch levels in low-fat diets. Treatments were (1) SARA Induction, (2) Recovery and (3) Control. Sub-acute ruminal acidosis was induced by feeding a diet containing 29.4% starch, 24.0% NDF and 2.8% fatty acids (FAs), whereas the Recovery and Control diets contained 19.9% starch, 31.0% NDF and 2.6% FA. Relative to Control, DM intake (DMI) and milk yield were higher in SARA from days 14 to 21 and from days 10 to 21, respectively (P < 0.05). Milk fat content was reduced from days 3 to 14 in SARA (P < 0.05) compared with Control, while greater protein and lactose contents were observed from days 14 to 21 and 3 to 21, respectively (P < 0.05). Milk fat yield was reduced by SARA on day 3 (P < 0.05), whereas both protein and lactose yields were higher on days 14 and 21 (P < 0.05). The ruminal acetate-to-propionate ratio was lower, and the concentrations of propionate and lactate were higher in the SARA treatment compared with Control on day 21 (P < 0.05). Plasma insulin increased during SARA, whereas plasma non-esterified fatty acids and milk ß-hydroxybutyrate decreased (P < 0.05). Similarly to fat yield, the yield of milk preformed FA (>16C) was lower on day 3 (P < 0.05) and tended to be lower on day 7 in SARA cows (P < 0.10), whereas yield of de novo FA (<16C) was higher on day 21 (P < 0.01) in the SARA group relative to Control. The t10- to t11-18:1 ratio increased during the SARA Induction period (P < 0.05), but the concentration of t10-18:1 remained below 0.5% of milk fat, and t10,c12 conjugated linoleic acid remained below detection levels. Odd-chain FA increased, whereas branched-chain FA was reduced during SARA Induction from days 3 to 21 (P < 0.05). Sub-acute ruminal acidosis reduced milk fat synthesis transiently. Such reduction was not associated with ruminal biohydrogenation intermediates but rather with a transient reduction in supply of preformed FA. Subsequent rescue of milk fat synthesis may be associated with higher availability of substrates due to increased DMI during SARA.

Peroxisome proliferator-activated receptor gamma (PPARγ) agonist fails to overcome trans-10, cis-12 conjugated linoleic acid (CLA) inhibition of milk fat in dairy sheep.

The trans-10, cis-12 conjugated linoleic acid (CLA) causes milk fat depression by downregulating expression of genes and transcription factors involved in lipogenesis and it has been proposed that peroxisome proliferator-activated receptor gamma (PPARγ) can be inhibited by trans-10, cis-12 CLA. The PPARγ is a nuclear receptor activated by natural or synthetic ligands and promotes expression of lipogenic genes and its effect on mammary lipogenesis and the interaction with trans-10, cis-12 CLA in lactating ewes was evaluated using thiazolidinedione (TZD), a chemical PPARγ agonist. A total of 24 lactating ewes were randomly assigned to one of the following treatments for 7 days: (1) Control (5 ml/day of saline solution); (2) TZD (4 mg/kg of BW/day in 5 ml of saline solution); (3) CLA (27 g/day with 29.9% of trans-10, cis-12); (4) TZD+CLA. Compared with Control, milk fat content was not changed by TZD, but was decreased 22.3% and 20.5% by CLA and TZD+CLA treatments. In the mammary gland, TZD increased PPARγ gene expression by 174.8% and 207.8% compared with Control and TZD+CLA treatments, respectively. Conjugated linoleic acid reduced sterol regulatory element-binding transcription protein 1 (SREBP1) gene expression 89.2% and 75.3% compared with Control and TZD+CLA, respectively, demonstrating that TZD fails to overcome CLA inhibition of SREBP1 signaling. In adipose tissue, the expression of SREBP1 and stearoyl CoA desaturase 1 (SCD1) genes were increased by the TZD+CLA treatment, compared with the other treatments. Conjugated linoleic acid decreased milk fat concentration and expression of lipogenic genes, while TZD had no effect on milk fat concentration, expression of lipogenic enzymes or regulators in the mammary gland and failed to overcome the inhibition of these by CLA. Therefore, CLA inhibition of milk fat synthesis was independent of the PPARγ pathway in lactating dairy ewes.

Green leaf allowance and dairy ewe performance grazing on tropical pasture.

The objective of this study was to explain the influence of green leaf allowance levels on the performance of dairy ewes grazing a tropical grass. Seventy-two lactating ewes grazed Aruana guineagrass (Panicum maximum Jacq. cv. Aruana) for 80 d. The treatments were 4 daily levels of green leaf allowance (GLA) on a DM basis corresponding to 4, 7, 10, and 13 kg DM/100 kg BW, which were named low, medium-low, medium-high, and high level, respectively. The experimental design was completely randomized with 3 replications. During the experimental period, 4 grazing cycles were evaluated in a rotational stocking grazing method (4 d of grazing and 16 d of rest). There was a linear effect of GLA on forage mass, and increasing GLA resulted in increased total leaf mass, reaching an asymptotic plateau around the medium-high GLA level. The stem mass increased with increased GLA, and a pronounced increase was observed between medium-high and high GLAs. Increasing GLA increased both forage disappearance rate and postgrazing forage mass. Leaf proportion increased with GLA, peaking at the medium-high level, and the opposite occurred for stem proportions, which reduced until medium-high GLA level, followed by an increase on high GLA. Forage CP decreased linearly with GLA, and increasing GLA from low to high reduced CP content by 31%. On the other hand, NDF increased 14% and ADF increased 26%, both linearly in response to greater GLA levels. Total digestible nutrients decreased linearly by 8% when GLA increased from low to high level. Milk yield increased, peaking at medium-high GLA (1.75 kg ewe(-1) d(-1)) and decreased at high GLA level (1.40 kg ewe(-1) d(-1)). Milk composition was not affected by the GLA levels. There was a reduction in stocking rate from 72 to 43 ewes/ha when GLA increased from low to high level. Productivity (milk yield kg ha(-1) d(-1)) increased as GLA increased, peaking at medium-low level (115 kg ha(-1) d(-1)). Although this tropical grass showed the same pattern in responses to GLA levels as reported in the literature with temperate pastures, the magnitude of the process changed and the maximum response in milk yield from lactating dairy ewes grazing a tropical pasture would be achieved with higher forage allowances than in temperate pastures. Overall, Aruana guineagrass grazed by lactating dairy ewes should be managed to provide 7 to 10 GLA in kg DM/100 kg BW according to the production goals.