Effect of dexamethasone on gene expression of cannabinoid receptor type 1 and adenosine monophosphate-activated protein kinase in the hypothalamus of broilers (Gallus domesticus).

Hypothalamic neural circuits play a critical role in integrating peripheral signals and conveying information about energy and nutrient status. We detected cannabinoid receptor type 1 (CB1) distribution in the hypothalamus, liver, duodenum, jejunum, and ileum among 7- and 35-day-old broilers. The effects of dexamethasone (DEX) on CB1 gene expression were evaluated by in vitro and in vivo experiments on glucocorticoid receptor (GR) and adenosine monophosphate-activated protein kinase (AMPK) in the hypothalamus of broilers. In vitro, hypothalamic cells from 17-day-old broiler embryos were incubated with either 0.1% dimethyl sulfoxide or DEX (100 nmol/mL) for 1 h. In the in vivo study, 28-day-old broilers were injected with DEX for 24 h or 72 h. Results showed that CB1 was mainly expressed in the hypothalamus, and 72 h DEX treatment increased the expression. One-day treatment of broilers with DEX did not change the hypothalamic CB1 gene expression. Moreover, DEX treatment for 24 h and 72 h increased the mRNA level of hypothalamic AMPKα2 and GR. However, no differences were observed on the gene expression of CB1, GR, and AMPKα2 in hypothalamic cells with DEX-treated for 1 h. In conclusion, CB1 is mainly expressed in the hypothalamus of broilers; 72-h DEX exposure can regulate the CB1 system and AMPK signaling pathway of the broiler hypothalamus.

Effects of dietary corticosterone on the central adenosine monophosphate-activated protein kinase (AMPK) signaling pathway in broiler chickens.

Glucocorticoids (GCs) induce the activation of the central adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling pathway in birds. In this study, we aimed to investigate the effects of corticosterone (CORT) supplemented in diet on the central AMPK signaling pathway in broilers. The average daily gain was reduced by CORT treatment, and the average daily feed intake remained unchanged. Plasma glucose, triglyceride, total cholesterol, and CORT contents were increased by CORT administration. In addition, CORT treatment decreased the relative weights of heart, spleen, and bursa and increased the relative weights of liver and abdominal fat. The glycogen contents in the liver and breast muscle were higher in the chicks treated with CORT. CORT treatment upregulated the gene expression of mammalian target of rapamycin, glucocorticoid receptor, AMPKα2, neuropeptide Y(NPY), liver kinase B1 (LKB1), AMPKα1, and fatty acid synthase in the hypothalamus. Moreover, CORT treatment increased the protein levels of acetyl-coenzyme A carboxylase (ACC) phosphorylation and total AMPK and phosphorylated AMPK in the hypothalamus. Hence, CORT administration in the diet activated the LKB1-AMPK-NPY/ACC signaling pathway in the hypothalamus of broiler.

Effects of dietary energy level on appetite and central adenosine monophosphate-activated protein kinase (AMPK) in broilers.

Adenosine monophosphate-activated protein kinase (AMPK) acts as a sensor of cellular energy changes and is involved in the control of food intake. A total of 216 1-d-old broilers were randomly allotted into 3 treatments with 6 replicates per treatment and 12 broilers in each cage. The dietary treatments included 1) high-energy (HE) diet (3,500 kcal/kg), 2) normal-energy (NE) diet (3,200 kcal/kg), and 3) low-energy (LE) diet (2,900 kcal/kg). The present study was conducted to investigate the effects of dietary energy level on appetite and the central AMPK signal pathway. The results showed that a HE diet increased average daily gain (ADG), whereas a LE diet had the opposite effect (P < 0.05, N = 6). The average daily feed intake (ADFI) of the chickens fed the LE diet was significantly higher than that of the control (P < 0.05, N = 6). Overall, the feed conversion rate gradually decreased with increasing dietary energy level (P < 0.05, N = 6). Moreover, the chickens fed the LE and HE diets demonstrated markedly improved urea content compared with the control group (P < 0.0001, N = 8). The triglyceride (TG) content in the LE group was obviously higher than that in the HE group but showed no change compared with the control (P = 0.0678, N = 8). The abdominal fat rate gradually increased with increased dietary energy level (P = 0.0927, N = 8). The HE group showed downregulated gene expression levels of liver kinase B1 (LKB1), neuropeptide Y (NPY), cholecystokinin (CCK), and glucocorticoid receptor (GR) in the hypothalamus compared with the control group (P < 0.05, N = 8). However, LE treatment significantly increased the mRNA level of AMP-activated protein kinase α2 (AMPKα2) compared with other groups (P = 0.0110, N = 8). In conclusion, a HE diet inhibited appetite and central AMPK signaling. In contrast, a LE diet activated central AMPK and appetite. Overall, the central AMPK signal pathway and appetite were modulated in accordance with the energy level in the diet to regulate nutritional status and maintain energy homeostasis in birds.

Alpha-lipoic acid impairs body weight gain of young broiler chicks via modulating peripheral AMPK.

In mammals, the AMP-activated protein kinase (AMPK) pathways in the central and peripheral tissues coordinately integrate inputs from multiple sources to regulate energy balance. The present study was aimed to explore the potential role of hepatic AMPK in the energy homeostasis of broiler chickens. Diets with 0, 0.05% or 0.1% alpha-lipoic acid (α-LA), a known AMPK inhibitor were provided to broiler chicks for 7days. As a result, α-LA supplementation decreased the relative growth rate of broiler chicks. Hepatic AMPKα2 mRNA levels were significantly upregulated by dietary α-LA, in concert with the increased phosphorylated AMPKα protein levels. In addition, hepatic FAS mRNA levels together with the malonyl-CoA to total CoA ester ratio were reduced by α-LA supplementation. Moreover, the hepatic phosphorylated glycogen synthase levels were increased resulting in a markedly decreased hepatic glycogen content. In conclusion, dietary α-LA supplementation decreased the in vivo hepatic glycogenesis and lipogenesis via stimulating hepatic AMPKα mRNA levels and the phosphorylated gene product. The stimulatory effect of α-LA on hepatic AMPK mRNA and pAMPKα protein levels together with our previous observations regarding its inhibitory effect on hypothalamic AMPK may have altered the energy balance and hence impaired body weight gain of broiler chicks.

Chenodeoxycholic acid reduces feed intake and modulates the expression of hypothalamic neuropeptides and hepatic lipogenic genes in broiler chickens.

Bile acids have recently become an emerging research hot spot in mammals due to their roles as metabolic regulators and molecular signatures controlling whole-body metabolic homeostasis. Such effects are still unknown in avian (non-mammalian) species. We, therefore, undertook this study to determine the effect of chenodeoxycholic acid (CDCA) on growth performance and on the expression of hypothalamic neuropeptides and hepatic lipogenic genes in broiler chickens. Chickens fed with diet-containing 0.1% or 0.5% CDCA for two weeks exhibited a significant and a dose dependent reduction of feed intake and body weight compared to the control (standard diet). These changes were accompanied with a significant decrease in plasma glucose levels at d10 and d15 post-treatment. At molecular levels, CDCA treatment significantly up-regulated the expression of feeding-related hypothalamic neuropeptides (NPY, AgRP, ORX, CRH, Ghrl, and MC1R) and down-regulated the hypothalamic expression of SOCS3. CDCA treatment also decreased the mRNA levels of key hepatic lipogenic genes (FAS, ACCα, ME, ATPcl, and SCD-1) and their related transcription factors SREBP-1/2 and PPARα. In addition, CDCA reduced the hepatic expression of FXR and the adipokine, visfatin, and adiponectin genes compared to the control. Together, our data provide evidence that CDCA alters growth performances in broilers and modulates the expression of hypothalamic neuropeptides and hepatic lipogenic and adipocytokine genes.

AMPK is involved in the differential neonatal performance of chicks hatching at different time.

We have recently reported that the hatching time may be in relation to the distinct neonatal performance of female chicks. The present study was aimed to investigate the potential involvement of AMPK, an energy sensor which plays a pivotal role in energy homeostasis, in the distinct performance of the spread of hatching time model. As a result, hypothalamic AMPKα1 isoform gene expression was significantly higher in the late hatcher as compared to that of their early counterparts, whereas the total and phosphorylated levels of AMPKα subunit did not differ between the three hatchers. The hypothalamic orexigenic NPY and AgRP mRNA levels were higher in the late hatchers as compared to the early, and that of the middle hatchers was at an intermediate level. However, the anorexigenic POMC and CRH was also higher expressed in the late hatchers as compared to the early hatchers. In the liver, AMPKα2 mRNA level and the phosphorylation ratio of AMPKα was significantly lower in the late hatchers, as compared to their early counterparts. The hepatic phosphorylated GS levels of the late and middle hatchers were lower than that of their early counterparts. The expression of hepatic FTO gene of the late hatchers was significantly higher than that of their early and middle counterparts. Taken together, AMPK may play a significant role in the different neonatal performance of the spread of hatching time model. The central and peripheral AMPK in late hatchers exhibited a pattern of higher energy intake and lower energy expenditure, which resulted in a faster post-hatch growth.

Limited evidence for trans-generational effects of maternal dietary supplementation with ω-3 fatty acids on immunity in broiler chickens.

The aim of the present study was to investigate whether the immune response of broiler chickens is modulated by including different omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) in the maternal diet. Broiler breeder hens (n = 120 birds per group) were fed one of four diets, differing in the ratios of n-6:n-3 PUFAs and eicosapentaenoic acid (EPA):docosahexaenoic acid (DHA). At 28 weeks of age, the eggs produced were incubated to obtain 720 chicks (n = 180 per group). All broiler chicks were fed a control diet and were vaccinated against Newcastle disease virus (NDV). Blood samples were taken at different time points after immunisation with human serum albumin (HuSA) in Freund's adjuvant to determine the acute phase response, antibody response and cytokine production. Addition of EPA to the maternal diet was associated with greater ovotransferrin concentrations post-immunisation, compared to other groups. Altering the ratios of n-6:n-3 PUFA or EPA:DHA in the maternal diet did not affect the offspring in terms of production of caeruloplasmin, α1-acid glycoprotein, interleukin (IL)-1ß, IL-6, IL-12 or tumour necrosis factor (TNF)-α. Dietary manipulation of the maternal diet did not influence the specific antibody response to HuSA or NDV, nor did it alter the levels of natural antibody binding to keyhole limpet haemocyanin in the offspring. Thus, maternal supplementation with n-3 PUFAs played a minor role in perinatal programming of the immune response of broiler chickens.

Transition of maternal dietary n-3 fatty acids from the yolk to the liver of broiler breeder progeny via the residual yolk sac.

The aim of the present study was to evaluate the transfer of maternal dietary fatty acids (FA) from the yolk to the developing offspring, with special emphasis on n-3 FA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Six hundred forty Ross 308 breeders were housed from 6 to 58 wk of age in 16 pens resulting in 4 replicates per dietary treatment. They were fed 1 of 4 diets: a basal diet, rich in n-6 FA (CON), or an n-3 FA enriched diet formulated to obtain an EPA/DHA ratio of 1/1 (EPA=DHA), 1/2 (DHA), or 2/1 (EPA). At 28, 43, and 58 wk of age, 20 eggs per treatment were collected and analyzed for FA composition. At these same breeder ages, 600 fertilized eggs per treatment were incubated. At hatch the residual yolks of 25 chicks per treatment were collected and analyzed for FA composition. At every hatch, 180 chicks per treatment were raised under standard conditions and livers were sampled at d 1, 14, 28, and 38 d for FA analysis. Concentrations of EPA in the yolk and residual yolk of eggs laid by EPA-fed breeders were highest, next-to-highest for EPA=DHA-fed breeders, next-to-lowest for DHA-fed breeders, and lowest in those laid by control hens, reflecting the inclusion levels in the maternal diets. Yolk and residual yolk DHA concentrations, however, were not only elevated due to DHA supplementation, compared with the control diet, but also due to EPA supplementation. Offspring hepatic EPA concentrations were elevated until d 28 in all n-3 enriched groups, whereas hepatic DHA concentrations were only affected by EPA=DHA and DHA supplementation at d 1. No differences were found in hepatic DHA concentrations at later offspring ages. Considering the role of EPA and DHA in early development and growth, the maternal supply of these n-3 FA might improve offspring health and performance.

The anorectic effects of alpha-lipoicacid are mediated by central AMPK and are not due to taste aversion in chicken (Gallus gallus).

AMP-activated protein kinase (AMPK) is an evolutionary conserved cellular energy sensor, which plays a pivotal role in mammalian energy homeostasis. The present study was aimed to explore the possible involvement of hypothalamic AMPK in feed intake regulation of broiler chickens. Hence, diets with 0, 0.05% or 0.1% α-lipoicacid (α-LA), a known AMPK inhibitor in mammals, were provided to broiler chicks for 7days. Alpha-LA exerted an anorectic effect, and the conditioned taste aversion test demonstrated that the effect was due to the alteration in satiety and not taste effects. However, the curtailed feed intake induced by α-LA disappeared on day 7. Hypothalamic AMPKα1 mRNA levels were significantly decreased by the dietary α-LA in concert with the reduced abundance in total AMPKα protein. The phosphorylated AMPKα was also decreased to a similar extend, resulting in an unaltered phosphorylated AMPKα/total AMPKα ratio. In addition, hypothalamic corticotropin releasing hormone mRNA levels were enhanced by α-LA. Interestingly, the mRNA expressions of hypothalamic orexigenic agouti-related peptide and neuropeptide Y were up-regulated, while the anorexigenic proopiomelanocortin and its transcription regulator hypoxia-inducible factor-1α were down-regulated, probably as a physiological reaction in order to counteract the altered energy balance. In conclusion, dietary α-LA decreased feed intake of broiler chicks. The anorectic effect was due to the reduced hypothalamic phosphorylated AMPKα as reflected in its decreased mRNA and protein levels. However, the anorectic effect of α-LA was progressively diminished after 7days of treatment, likely by a physiological counteractive feedback via changing neuropeptides involved in energy balance regulation.

Impact of feed supplementation with different omega-3 rich microalgae species on enrichment of eggs of laying hens.

Four different omega-3 rich autotrophic microalgae, Phaeodactylum tricornutum, Nannochloropsis oculata, Isochrysis galbana and Chlorella fusca, were supplemented to the diet of laying hens in order to increase the level of omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) in egg yolk. The microalgae were supplemented in two doses: 125 mg and 250 mg extra n-3 PUFA per 100g feed. Supplementing these microalgae resulted in increased but different n-3 LC-PUFA levels in egg yolk, mainly docosahexaenoic acid enrichment. Only supplementation of Chlorella gave rise to mainly α-linolenic acid enrichment. The highest efficiency of n-3 LC-PUFA enrichment was obtained by supplementation of Phaeodactylum and Isochrysis. Furthermore, yolk colour shifted from yellow to a more intense red colour with supplementation of Phaeodactylum, Nannochloropsis and Isochrysis, due to transfer of carotenoids from microalgae to eggs. This study shows that besides Nannochloropsis other microalgae offer an alternative to current sources for enrichment of hen eggs.

The endocrine control of energy homeostasis in chickens.

Energy homeostasis (balance) depends on the relationship between the amount of consumed feed energy and energy expenditure. Coordination of energy expenditure and feed intake (appetite) is necessary for the regulation of body composition. The hypothalamus integrates peripheral and central signals to generate satiety or hunger. Birds and mammals utilize common signaling molecules but some molecules possess different/opposite functions. If relevant, particular differences with the mammalian regulatory system are highlighted in this review. For example, obestatin had no significant effect on feed intake of chicks, but it was claimed to decrease food intake in mammalian species. Ghrelin displayed appetite-stimulating effects in mammals but appetite-decreasing effects in birds. Recently, the function of the hypothalamic AMPK signaling pathway on feed intake regulation has received considerable attention in poultry. Alpha-lipoic acid might exert its appetite-decreasing effect by the AMPK signaling pathway. This review discusses the central regulation of energy homeostasis, role of (an)orexigenic peptides, effect of feed deprivation on hypothalamic neuropeptide gene expression and provides a model for involvement of AMPK in the regulation of avian energy balance.

Chicken FTO gene: tissue-specific expression, brain distribution, breed difference and effect of fasting.

Fat mass and obesity-associated (FTO) gene is widely expressed in central and peripheral tissues of mammals, and exhibits a range of functions, especially in energy balance. However, basic knowledge of FTO in the chicken is lacking. Therefore, we studied the tissue distribution, age and breed dependent changes, brain localization, as well as the impact of fasting on FTO mRNA expression in the chicken. FTO mRNA was expressed in all the tissues studied, and generally, with high expression in hypothalamus, liver, visceral fat and cerebellum. However it exhibited breed-specific patterns: in broilers, the highest expression was seen in the liver, while in layers, hypothalamus and cerebellum showed relatively higher FTO mRNA expression. One-week-old broilers expressed markedly higher FTO mRNA in liver compared with the layers of the same age (P<0.01), while the breed difference was reversed in visceral fat and cerebellum (P<0.05). Compared with newly hatched chicks (one week of age), adult layers expressed higher FTO mRNA in liver and visceral fat, while adult broilers showed higher expression in hypothalamus and cerebellum. In situ hybridization demonstrated distribution of FTO mRNA in paraventricularis magnocellularis (PVN), nucleus ventromedialis hypothalami (VMN), nucleus lateralis hypothalami (LHy), nucleus dorsomedialis hypothalami (DMN) of the hypothalamus and nucleus habenularis medialis (HM) and stratum cellulare externum (SCE) of the thalamus. Breed-specific expression of FTO mRNA was shown in PVN, but not in VMN, with higher abundance in broilers compared to layers. The decrease in FTO mRNA levels after 24h of fasting was seen only in VMN of layer chickens. These results may provide some intriguing hints for further investigation of FTO function in the chicken.

Fasting alters protein expression of AMP-activated protein kinase in the hypothalamus of broiler chicks (Gallus gallus domesticus).

An experiment was conducted to investigate the effects of fasting and re-feeding on hypothalamic 5'-AMP-activated protein kinase (AMPK) levels and (an)orexigenic neuropeptides. Male Arbor Acres chicks (7-day-old, n=160) were allocated to four equal treatment groups: control chicks (fed ad libitum for 48 h, C48), chicks that were fasted for 48 h (F48), chicks that were first fasted for 48 h and then re-fed for 24h (F48C24), and chicks that were fed ad libitum for 72h (C72). Fasting for 48 h significantly (P<0.05) increased the ratio of phosphorylated AMPKα to total AMPKα and phosphorylated LKB1 to total LKB1, whereas re-feeding for 24h reduced these ratios to that of the ad libitum fed C72 chicks. The gene expressions of agouti-related peptide (AgRP), neuropeptide Y (NPY), melanocortin receptor 4, melanin-concentrating hormone, prepro-orexins and carnitine palmitoyltransferase-1 were significantly (P<0.05) increased in the fasted chicks relative to the ad libitum fed C48 group. The gene expression of pro-opiomelanocortin (POMC), as well as cocaine- and amphetamine-regulated transcript (CART) was not affected by the nutritional status. Fasting significantly (P<0.05) decreased the mRNA levels of fatty acid synthase (FAS) and sterol regulatory element binding protein-1 (SREBP-1). The results suggest that the LKB1/AMPK signal pathway is involved in the energy homeostasis of fasted chicks, and its possible role in feed intake regulation might be mediated by the AgRP/NPY rather than the POMC/CART pathway.

Effects of dietary protein content and 2-hydroxy-4-methylthiobutanoic acid or DL-methionine supplementation on performance and oxidative status of broiler chickens.

Besides its typical role as an amino acid in protein synthesis, methionine is an important intermediate in methylation reactions. In addition, it can also be converted to cysteine and hence plays a role in the defence against oxidative stress. The present study was conducted to investigate further the role of DL-methionine (DLM) and its hydroxy analogue, DL-2-hydroxy-4-methylthiobutanoic acid (DL-HMTBA), on zootechnical performance and oxidative status of broiler chickens. Male broiler chickens were reared on two diets differing in crude protein (CP) content (low-protein, 18·3 % v. high-protein, 23·2 % CP) and were supplemented either with 0·25 % DLM or 0·25 % DL-HMTBA. Reducing the dietary protein content resulted in an impaired body weight gain (P < 0·0001). However, supplementation of DL-HMTBA to the low-protein diet partially alleviated these negative effects (P = 0·0003). This latter phenomenon could be explained by the fact that chickens fed DL-HMTBA-supplemented diets displayed a better antioxidant status as reflected in lower lipid peroxidation probably as a consequence of their higher hepatic concentrations of total and reduced glutathione compared with their DLM counterparts. On the other hand, within the high protein levels, uric acid might be an important antioxidant to explain the lower lipid peroxidation of high-protein DL-HMTBA-supplemented chickens. Hepatic methionine sulfoxide reductase-A gene expression was not significantly affected by the dietary treatments. In conclusion, the present study indicates that there are interactions between dietary protein content and supplementation of methionine analogues with respect to broiler performance and antioxidant status, also suggesting a causal link between these traits.

Intestinal fermentation modulates postprandial acylcarnitine profile and nitrogen metabolism in a true carnivore: the domestic cat ( Felis catus).

N balance and postprandial acylcarnitine profile following intestinal fermentation of oligofructose and inulin were investigated in healthy cats. Two diets were tested in a crossover design: a commercial high-protein cat food supplemented with 4 % DM oligofructose and inulin (spectrum: degree of polymerisation (DP) 2-10: 60 (SE 5) % DM; DP>10: 28 (SE 5) % DM) as high-fermentable fibre (HFF) diet, and the same commercial diet supplemented with 4 % DM cellulose as low-fermentable fibre diet. Eight adult cats were randomly allotted to each of the two diets at intervals of 4 weeks. At the end of each testing period, faeces and urine were collected over a 5-d period, and blood samples were obtained before and at the selected time points postprandially. No differences were found for N intake, N digestibility and faecal N excretion, whereas urinary N excretion was lower when the HFF diet was fed (P = 0.044). N balance was positive in all the cats, and tended to be increased when the HFF diet was fed (P = 0.079). Propionylcarnitine concentrations (P = 0.015) and their area under the curve (AUC) (P = 0.013) were increased when the HFF diet was fed, revealing a more pronounced production and absorption of propionate. Yet, methylmalonylcarnitine concentrations and concurrent AUC were not elevated when the HFF diet was fed, indicating reduced amino acid catabolism. 3-Hydroxy-3-methylglutarylcarnitine concentrations (P = 0.026) and their AUC (P = 0.028) were also reduced when the HFF diet was fed, implying diminished use of branched-chain amino acids as well. In healthy cats, oligofructose and inulin added to a high-protein diet were suggested to reduce postprandial amino acid-induced gluconeogenesis by substitution with propionate.

Oligofructose and inulin modulate glucose and amino acid metabolism through propionate production in normal-weight and obese cats.

The effect of dietary oligofructose and inulin supplementation on glucose metabolism in obese and non-obese cats was assessed. Two diets were tested in a crossover design; a control diet high in protein (46 % on DM basis), moderate in fat (15 %), low in carbohydrates (27 %), but no soluble fibres added; and a prebiotic diet, with 2.5 % of a mixture of oligofructose and inulin added to the control diet. Eight non-obese and eight obese cats were allotted to each of two diets in random order at intervals of 4 weeks. At the end of each testing period, intravenous glucose tolerance tests were performed. Area under the glucose curve (AUCgluc) was increased (P = 0.022) and the second insulin peak was delayed (P = 0.009) in obese compared to non-obese cats. Diets did not affect fasting plasma glucose concentrations, blood glucose response at each glucose time-point after glucose administration, AUCgluc, fasting serum insulin concentrations, area under the insulin curve, and height and appearance time of insulin response. Yet, analysis of acylcarnitines revealed higher propionylcarnitine concentrations (P = 0.03) when fed the prebiotic diet, suggesting colonic fermentation and propionate absorption. Prebiotic supplementation reduced methylmalonylcarnitine (P = 0.072) and aspartate aminotransferase concentrations (P = 0.025), both indicating reduced gluconeogenesis from amino acids. This trial evidenced impaired glucose tolerance and altered insulin response to glucose administration in obese compared to non-obese cats, regardless of dietary intervention; yet modulation of glucose metabolism by enhancing gluconeogenesis from propionate and inhibition of amino acid catabolism can be suggested.

Peripartal feeding strategy with different n-6: n-3 ratios in sows: effects on sows' performance, inflammatory and periparturient metabolic parameters.

The present study aimed to investigate the effects of two lactation sow feeds, differing in n-6:n-3 ratio, given to sows before parturition on body condition and feed intake, periparturient metabolism (leptin, insulin, triiodothyronine (T3) and thyroxine (T4)), inflammatory parameters (TNFalpha, IL-6, serum amyloid A (SAA)) and on piglet performance (birth weight, survivability). The feed contained either a low (supplemented with fish oil; f groups) or high (supplemented with sunflower-seed oil; s groups) n-6:n-3 ratio and was administered from 8 d (f8, s8) or 3 d (f3, s3) before parturition until weaning. The level of inclusion of the oil sources was 2 %. Seventy-two sows were randomly allocated 8 d before expected farrowing into four groups: f3, f8, s3, s8. Type of feed had a significant influence on the sows' feed intake during the first 2 d of lactation (s < f), leptin on days 4, 3 and 2 before parturition (f < s), insulin on day 1 after parturition (f < s), T4 on the day before parturition (s < f) and rectal temperature on the day after parturition (f < s). Onset of administration of the feed (3 v. 8 d) had significant effects on leptin on day 2 before parturition (8 < 3), insulin on day 4 before parturition (3 < 8), T3 on day 4 before parturition and on the day after parturition (3 < 8), SAA on day 3 after parturition (8 < 3) and piglet weight during the first days postpartum (3 < 8). In conclusion, under the present conditions, a lactation feed low in n-6:n-3 ratio administered from 8 d before farrowing ensures improved feed intake during the first days postpartum and was associated with a better metabolic change and inflammatory profile in sows in the periparturient period.

Dietary L-carnitine supplementation enhances the lipopolysaccharide-induced acute phase protein response in broiler chickens.

The objective of the present study was to evaluate the potential effects of dietary L-carnitine supplementation on acute phase protein response upon a lipopolysaccharide (LPS) challenge of male broiler chickens receiving a commercial broiler diet supplemented with 15 or 100 mg L-carnitine/kg or an unsupplemented (control) diet from 14 days of age onwards. At 28 days of age, eight chickens per dietary treatment were weighed and subcutaneously injected with 300 microg LPS from E. coli (100 microg LPS/ml saline) or 3 ml saline (unsupplemented group only). During the next 10 days, blood samples were taken repeatedly and analysed for their hemopexin (HX) and alpha-1 acid glycoprotein (AGP) levels. Extra dietary L-carnitine did not affect broiler performance. At day 1 postinjection, plasma HX and AGP levels were significantly increased in all treatment groups. However, the elevations in circulating HX and AGP levels were more pronounced in the L-carnitine supplemented chickens, especially in the 100mg L-carnitine group. It is concluded that extra L-carnitine in the diet of broiler chickens enhances or advances the acute phase protein response. The exact mode of action needs to be elucidated but seems to be consistent with a glucocorticoid mimicking effect.

Leptin downregulates heat shock protein-70 (HSP-70) gene expression in chicken liver and hypothalamus.

Heat shock protein (HSP)-70 is expressed in normal and stressed cells but is highly stress-inducible. Although leptin has long been suggested to be involved in the regulation of stress response, its interaction with the HSP-70 gene is still unknown, under both unstressed and stressed conditions. The present study has aimed to investigate the effect of leptin on HSP-70 gene expression in normal chicken liver, hypothalamus, and muscle. Continuous infusion of recombinant chicken leptin (8 mug/kg per hour) at a constant rate of 3 ml/h for 6 h in 3-week-old broiler chickens significantly (P < 0.05) decreased food intake and HSP-70 mRNA levels in liver and hypothalamus, but not in muscle. In an attempt to discriminate between the effect of leptin and of leptin-reduced food intake on HSP-70 gene expression, we also evaluated the effect of food deprivation on the same cellular responses in two broiler chicken lines genetically selected for low (LL) or high (FL) abdominal fat pad size. Food deprivation for 16 h did not affect HSP-70 gene expression in any of the studied tissues indicating that the effect of leptin was independent of the inhibition of food intake. Regardless of the nutritional status, HSP-70 mRNA levels were significantly (P < 0.05) higher in the hypothalamus of FL compared with LL chickens consistent with higher mRNA levels for hypothalamic corticotropin-releasing factor. To assess, whether the effects of leptin were direct or indirect, we carried out in vitro studies. Leptin treatments did not affect HSP-70 mRNA levels in a leghorn male hepatoma cell line or quail myoblast cell line suggesting that the effect of leptin on HSP-70 gene expression is mediated through the central nervous system. Furthermore, HSP-70 gene expression was gender-dependent with significantly (P < 0.05) higher levels in male than in female chickens.

The regulation of stearoyl-CoA desaturase gene expression is tissue specific in chickens.

Emerging evidence suggests a potential role of stearoyl-CoA desaturase (SCD)-1 in the control of body weight and energy homeostasis. The present study was conducted to investigate the effects of several energy balance-related factors (leptin, cerulenin, food deprivation, genotype, and gender) on SCD gene expression in chickens. In experiment 1, 6-week-old female and male broiler chickens were used. In experiment 2, two groups of 3-week-old broiler chickens were continuously infused with recombinant chicken leptin (8 micro g/kg/h) or vehicle for 6 h. In experiment 3, two groups of 2-week-old broiler chickens received i.v. injections of cerulenin (15 mg/kg) or vehicle. In experiment 4, two broiler chicken lines (fat and lean) were submitted to two nutritional states (food deprivation for 16 or 24 h and feeding ad libitum). At the end of each experiment, tissues were collected for analyzing SCD gene expression. Data from experiment 1 showed that SCD is ubiquitously expressed in chicken tissues with highest levels in the proventriculus followed by the ovary, hypothalamus, kidney, liver, and adipose tissue in female, and hypothalamus, leg muscle, pancreas, liver, and adipose tissue in male. Female chickens exhibited significantly higher SCD mRNA levels in kidney, breast muscle, proventriculus, and intestine than male chickens. However, hypothalamic SCD gene expression was higher in male than in female (P < 0.05). Leptin increased SCD gene expression in chicken liver (P < 0.05), whereas cerulenin decreased SCD mRNA levels in muscle. Both leptin and cerulenin significantly reduced food intake (P < 0.05). Food deprivation for either 16 or 24 h decreased the hepatic SCD gene expression in fat line and lean line chickens compared with their fed counterparts (P < 0.05). The hypothalamic SCD mRNA levels were decreased in both lines only after 24 h of food deprivation (P < 0.05). In conclusion, SCD is ubiquitously expressed in chickens and it is regulated by leptin, cerulenin, nutritional state, and gender in a tissue-specific manner.