ß2 adrenergic receptors and leptin interplay to decrease food intake in chicken.

1. The present study was designed to examine the effects of intracerebroventricular (ICV) injection of different α and [Formula: see text] adrenergic receptor antagonists on leptin-induced hypophagia in broiler chickens.2. The study consisted of six experiments. In all experiments, chickens were deprived of feed for 3 h prior to the ICV injections and thereafter were returned immediately to the individual cages and cumulative feed intake, based on the percentage of body weight, was measured at 30, 60 and 120 min post-injection.3. In experiment 1, leptin (2.5, 5 or 10 µg) were injected in birds. In experiment 2, groups received either control solution, prazosin (10 nmol), leptin (10 µg) or a co-injection of prazosin (10 nmol) and leptin (10 µg). The other experiments were conducted as experiment 2, but instead of prazosine (10 nmol), yohimbine (13 nmol) was used in experiment 3, metoprolol (24 nmol) in experiment 4, ICI 118,551 (5 nmol) in experiment 5 and SR 59230R (5 nmol) in experiment 6 were injected either in a group or in combination with leptin (10 µg).4. The results of this study revealed a dose-dependent hypophagic effect of leptin and, in experiment 5, ICV co-injection of ICI118, 551 (5 nmol) and leptin (10 µg) significantly attenuated this effect (P˂0.5). These results suggest that the hypophagic effect of leptin is probably mediated by ß2 adrenergic receptors in chickens.

Consequence of dopamine D2 receptor blockade on the hyperphagic effect induced by cannabinoid CB1 and CB2 receptors in layers.

1. Endocannabinoids (ECBs) and their receptors play a regulatory function on several physiological processes such as feed-intake behaviour, mainly in the brain. This study was carried out in order to investigate the effects of the dopaminergic D1 and D2 receptors on CB1/CB2 ECB receptor-induced hyperphagia in 3-h feed-deprived neonatal layer chickens. 2. A total of 8 experiments were designed to explore the interplay of these two modulatory systems on feed intake in neonatal chickens. In Experiment 1, chickens were intracerebroventricular (ICV) injected with control solution, l-DOPA (levo-dihydroxyphenylalanine as precursor of dopamine; 125 nmol), 2-AG (2-arachidonoylglycerol as CB1 receptor agonist; 2 µg) and co-administration of l-DOPA (125 nmol) plus 2-AG (2 µg). Experiments 2-4 were similar to Experiment 1 except birds were injected with either 6-OHDA (6-hydroxydopamine as dopamine synthesis inhibitor; 150 nmol), SCH23390 (D1 receptor antagonist; 5 nmol) and AMI-193 (D2 receptor antagonist; 5 nmol) instead of l-DOPA, respectively. Additionally, Experiments 5-8 followed the previous ones using the same dose of l-DOPA, 6-OHDA and dopamine antagonists except that birds were injected with CB65 (CB2 receptor agonist; 5 µg) instead of 2-AG. Coadministrations were at the same dose for each experiment. Cumulative feed intakes were measured until 120 min after each injection. 3. ICV administration of 6-OHDA and AMI-193 significantly attenuated 2-AG-induced hyperphagia. Interestingly, the hyperphagic effect of CB65 was significantly attenuated by administration of l-DOPA, whereas the administration of 6-OHDA and AMI-193 together amplified the hyperphagic effect of CB65. 4. It was concluded that cannabinoid-induced feeding behaviour is probably modulated by dopamine receptors in neonatal layer-type chickens. It seems that their interaction may be mediated by the D2-dopamine receptor.

Central histaminergic system interplay with suppressive effects of immune challenge on food intake in chicken.

The aim of the current study was to investigate the interaction of the lipopolysaccharide (LPS) and histaminergic systems on appetite regulation in broilers. Effects of intracerebroventricular (ICV) injection of α-fluoromethylhistidine (α-FMH, histidine decarboxylase inhibitor), chlorpheniramine (histamine H1 receptor antagonist), famotidine (histamine H2 receptor antagonist) and thioperamide (histamine H3 receptor antagonist) on LPS-induced hypophagia in broilers were studied. A total of 128 broilers were randomly allocated into 4 experiments (4 groups and 8 replications in each experiment). A cannula was surgically implanted into the lateral ventricle. In Experiment 1, broilers were ICV injected with LPS (20 ng) prior to α-FMH (250 nmol). In Experiment 2, chickens were ICV injected with LPS followed by chlorpheniramine (300 nmol). In Experiment 3, broilers were ICV injected with famotidine (82 nmol) after LPS (20 ng). In Experiment 4, ICV injection of LPS was followed by thioperamide (300 nmol). Then, cumulative food intake was recorded until 4 h post-injection. According to the results, LPS significantly decreased food intake. Chlorpheniramine significantly amplified food intake, and LPS-induced hypophagia was lessened by injection of chlorpheniramine. α-FMH, famotidine and thioperamide had no effect on LPS-induced hypophagia. These results suggest that there is an interaction between central LPS and the histaminergic system where LPS-induced hypophagia is mediated by H1 histamine receptors in 3 h food-deprived broilers.

Lipopolysaccharide and histaminergic systems interact to mediate food intake in broilers.

1. The aim of the current study was to investigate the interaction of the lipopolysaccharide and histaminergic systems on appetite regulation in broilers. The effects of intracerebroventricular (ICV) injection of α-fluoromethylhistidine (α-FMH, histidine decarboxylase inhibitor), chlorpheniramine (histamine H1 receptor antagonist), famotidine (histamine H2 receptor antagonist) and thioperamide (histamine H3 receptor antagonist) on lipopolysaccharide (LPS)-induced hypophagia in broilers were studied. 2. A total of 128 broilers were randomly allocated into 4 experiments (4 groups and 8 replications in each experiment). A cannula was surgically implanted into the lateral ventricle. In Experiment 1, broilers were ICV injected with LPS (20 ng) prior to α-FMH (250 nmol). In Experiment 2, chickens were ICV injected with LPS followed by chlorpheniramine (300 nmol). In Experiment 3, broilers were ICV injected with famotidine (82 nmol) after LPS (20 ng). In Experiment 4, ICV injection of LPS was followed by thioperamide (300 nmol). The cumulative food intake was recorded until 4 h post injection. 3. LPS decreased food intake; chlorpheniramine amplified food intake and LPS-induced hypophagia was lessened by injection of chlorpheniramine. α-FMH, famotidine and thioperamide had no effect on LPS-induced hypophagia. 4. The results suggest that there is an interaction between central LPS and the histaminergic system where LPS-induced hypophagia is presumably mediated by H1 histamine receptors in 3 h food-deprived broilers.

Autophagy-regulating microRNAs: two-sided coin in the therapies of breast cancer.

Despite recent advances in the treatment of breast cancer (BC), it still remains as a prevalent and deadly cancer in the world. Given that BC is a heterogeneous disease, it is necessary to clarify molecular mechanisms in tumor cells to improve various therapy outcomes and overcome therapy resistance. Autophagy represents one of the most important intracellular degradation pathways involved in diverse biological processes and plays an important bi-directional role in tumor formation and progression. Among the several mechanisms that affect autophagy, microRNAs (miRNAs) play a crucial role as gene regulators. Several in vivo and in vitro studies have reported multiple miRNAs regulating autophagy in BC that affect tumor initiation, progression, and response to various therapies. In the present review, we highlighted the mechanisms through which miRNAs regulate autophagy in BC and their potential use as therapeutic targets.

Leptin receptor mRNA in bull ejaculated spermatozoa.

Leptin is a potential satiety factor and plays an important role in both metabolism and reproduction; both leptin and its receptor (Ob-R) have been detected in human spermatozoa, thus suggesting leptin involvement in male gamete physiology. This experiment was designed to investigate leptin receptor [the long isoform (Ob-Rb)] mRNA in bull ejaculated spermatozoa by RT-PCR and southern hybridization. Total RNA was isolated from ejaculated spermatozoa and purified by different methods. Although the concentrations of RNA determined by all methods (except SDS/Proteinase K, lowest amount of RNA recovery) were similar, ethidium bromide staining was only detectable in lanes containing the samples isolated by sodium dodecyl sulphate (SDS) and SDS/citric acid extraction which produced higher RNA concentration. Ob-Rb mRNA was detected in all samples using southern hybridization after RT-PCR; it was shown only in three of them by RT-PCR. We may conclude that Ob-Rb mRNA is present in bull spermatozoa and leptin perhaps exerts physiological effects, as already demonstrated in humans and pigs.

Microhandling of vesicular glutamate uptake modulate feeding in broilers.

Glutamate (Glu), the major excitatory neurotransmitter in vertebrate central nervous system, is actively taken up and stored in synaptic vesicles. On the arrival of an action potential to the pre-synaptic membrane and the subsequent opening of the voltage-gated calcium channels and movement of Ca(2+) into the neuron, these small vesicles fuse with the pre-synaptic membrane to release the neurotransmitter content into the synaptic cleft. Because it has previously been shown that intracerebroventricular (ICV) glutamate plays a role in feed intake in broilers, the manipulation of its vesicular concentration could affect feeding behaviour. On the contrary, research on vesicular glutamate transporters has, so far, been carried out on mammalian species. In the present study, we aim to examine the effect of Chicago sky blue 6B (CSB6B), a glutamate vesicular uptake inhibitor, on feed intake and latency to start feeding in a commercial strain of meat type chickens. To do this, four experiments have been designed to investigate the effect of ICV injection of saline, glutamate, as a general agonist for glutamate receptors, CSB6B and the combination of Glu and CSB6B. The findings indicate that CSB6B increases feed intake and decreases the latency to start feeding in 24-h-feed-deprived Ross 208 broilers.

Ascites syndrome in broilers: physiological and nutritional perspectives.

Broiler chickens are intensively selected for productive traits. The management of these highly productive animals must be optimal to allow their full genetic potential to be expressed. If this is not done, inefficient production and several metabolic diseases such as ascites become apparent. The causes of the ascites are multifactorial but diet and, particularly, interactions between diet, other environmental and genetic factors play an important role. The relatively high heritability estimates for ascites-related traits and the significance of maternal genetic effects for most of the traits indicate that direct and maternal genetic effects play an important role in development of the ascites syndrome. An imbalance between oxygen supply and the oxygen required to sustain rapid growth rates and high food efficiencies causes ascites in broiler chickens. Because of the relationship to oxygen demand, ascites is affected and/or precipitated by factors such as growth rate, altitude (hypoxia) and environmental temperature. As the high metabolic rate (fast growth) is a major factor contributing to the susceptibility of broilers to ascites, early-age feed or nutrient restriction (qualitative or quantitative) or light restriction in order to slow down the growth rate seem practically viable methods, since final body weight is not compromised. Manipulation of the diet composition and/or feed allocation system can have a major effect on the incidence of ascites. Optimization of the house temperature and ventilation in cold weather seem helpful practices to decrease ascites incidence.

Leptin mRNA expresses in the bull reproductive organ.

Leptin, a 167-amino acid hormone, is secreted mainly by fat tissue. It has some powerful effects on the regulation of metabolism and reproductive function through endocrine and probably paracrine mechanisms. The contribution rate of leptin function on the male reproductive system is not still clear. Characterization of leptin expression in reproductive organs will suggest that in addition to its endocrine action, leptin has also paracrine/autocrine effects on reproduction. The expression of functional leptin receptor mRNA has been already recognized in testis of rodents, human and cattle. Thus, the aim of the present study was to investigate the presence of leptin mRNA in the bovine testis, because it will be the first step for understanding of its paracrine/autocrine effects on the male reproductive organs in cattle. The present study was the first to showed leptin mRNA expression in the testis of Holstein cattle using reverse transcription and polymerase chain reaction (RT-PCR) analysis. RT-PCR products were amplified with nested PCR using inner leptin primer pairs to emphasis the first results. Besides, bovine beta actin gene was acted as an internal positive control as well as RNA purification marker. Our findings suggest that in addition to its endocrine actions at the hypothalamic-pituitary axis, leptin can has an autocrine and/or paracrine role in bull testicular function.