kimia mahdavi

During the last few decades, identifying the physiological pathways involved in appetite regulation has become popular among researchers. Although studying feeding regulation in birds, especially in poultry(for breeding purposes) and ornamental birds (for therapeutic purposes), is extremely important, limited experiments have been conducted on these animal models. Until today, more than 50neurotransmitters affecting birds' appetite have been identified. In the current study, we overviewed the role of one of the most important neural mediators, neuropeptide Y (NPY), in regulating avian appetite. Based on the findings, the presence of this neuropeptide and its receptors in the key areas of food intake regulation, especially the hypothalamus's arcuate nucleus (ARC), has been proven. Numerous studies on birds have repeatedly shown the hyperphagic effects of NPY. Among the different NPY receptors, type 1, 2, and 5 receptors play the most important role in appetite regulation. It has also been observed that the interaction of NPY with neurotransmitters such as glucagon-like peptide-1 (GLP-1), vasotocin, bombesin, opioids, alpha-melanocyte-stimulating hormone (α-MSH), cocaine-and amphetamine-regulated transcript (CART) and gamma aminobutyric acid (GABA) is effective in NPY-induced hyperphagia. In addition, the NPY system is also involved in the effects of various mediators such as adiponectin, neuropeptide W (NPW), phoenixin-14, visfatin, adrenomedullin, spexin, kisspeptin, insulin, and somatostatin on appetite regulation. Finally, NPY seems to be one of the most important appetite-stimulating factors in birds and also plays an undeniable role in theeffects of other neurotransmitters on appetite regulation.

The dopaminergic system plays an important role in modulating some neural functions such as motor control, motivation, pain, cognition, maternal behavior, and reward. Dopaminergic signaling pathways are very important for maintaining physiological processes, and an unbalanced activity may lead to disorders related to neurological diseases. A correct understanding of the neurobiology and underlying molecular mechanisms of these disorders leads to the development of new treatments that improve the quality of life of patients all over. The purpose of the present study is to review the research conducted on the central role of the dopaminergic system and the dimensions of its influence on various physiological functions. In this review, articles related to the topic in the years 1970 to 2023 were identified using a targeted search of related keywords in reliable databases such as Civilica, Web of Science, Scopus, Science Direct, PubMed, Springer, Google Scholar, and Elsevier, and in order to obtain more studies from the list The sources of these articles were used. Based on the findings of these studies, the appetite-reducing effects of dopamine have been reported in birds and mammals. On the other hand, the role of this neural mediator in pain perception and memory processing was determined. In connection with the endocrine glands, the interaction of dopamine with prolactin, sex steroids, growth hormone, and thyroid hormones has been proven. Also, numerous studies have shown the role of dopamine in motor control and the occurrence of maternal behavior. Finally, based on the review of past research, the occurrence of neurological diseases such as schizophrenia, Parkinson, Huntington, attention deficit/hyperactivity disorder (ADHA), and addiction can be related to abnormalities in the dopaminergic system. Despite conducting numerous studies on the role of the dopaminergic system in various biological activities, it is suggested to carry out more studies in order to identify new dimensions of the effect of this system on different body functions and to provide new treatment paths.
‎

Understanding the mechanism of food intake is important for comprehending energy balance, obesity, and the body weight regulation. In particular, examining birds' appetite is critical for conservation efforts, managing human-bird interactions, and understanding the environmental implications of bird feeding practices. In this systematic review, using the PRISMA guideline, we investigated the mediators that were identified as factors affecting the birds' appetite in 2022 and 2023. In order to obtain the appropriate studies, suitable keywords were searched in the relevant electronic databases and an anthology of the desired articles was done. According to the findings, the central administration of adrenomedullin, apelin-13, lipopolysaccharide, neuromedins and spexin causes hypophagia in chickens, while the injection of adiponectin, neuropeptide W (NPW) and phonexin-14 increased the food intake of birds. Also, regarding the members of RF-amide peptide family, neuropeptide VF (NPVF) and neuropeptide FF (NPFF) weakened the food consumption of birds, while kisspeptin and prolactin-releasing peptide (PrRP) strengthened it. The effects observed in birds were similar to mammals in most cases, indicating the structural and general similarities in the regulatory mechanisms of these strains, on the other hand, the contradictory effects between the two species were probably caused by genetic differences. Finally, despite the progress made in identifying the factors and mechanisms involved in regulating the appetite of birds, it is recommended to conduct future studies using modern laboratory methods, especially cellular-molecular methods.

According to previous studies, the serotonergic system plays a remarkable role in regulating meal intake, however, its role in the mediation of feeding caused by neuromodulin S (NMS) has not been investigated in birds. In the present research, 5 trials were considered in order to determine the links between these systems. In treatment 1, chickens received intracerebroventricular (ICV) infusion of NMS (0.25, 0.5, and 1 nmol). NMS (1 nmol), SB242084 (1.5 μg), a 5-HT2C receptor antagonist, and NMS + SB242084 were injected in the treatment 2. In subsequent treatments, instead of SB242084, 8-OH-DPAT (agonist of 5-HT1A receptor, 15.25 nmol), PCPA (serotonin synthesis inhibitor, 1.25 μg), and Fluoxetine (serotonin reuptake inhibitor, 10 μg) were applied. Then, total food consumption was recorded for 120 minutes. Based on observations, NMS dose-dependently attenuated meal intake (P<0.05). Hypophagia was diminished with NMS + SB242084 administration (P<0.05). ICV infusion of NMU + 8-OH-DPAT had no significant effect on the hypophagia (P≥0.05). The NMS-induced decreasing feed intake was attenuated with co-infusion of NMS+ PCPA (P< 0.05). Also, hypophagia was strengthened by NMS+ Fluoxetine co-infusion (P< 0.05). According to the results, the NMS-induced hypophagia is possibly mediated via 5-HT2c receptors in layer-type chickens.

5-Hydroxytryptamine or serotonin is a biogenic amine that is best known for its function as a neurotransmitter. One of the most important effects of serotonin is its role in regulating food intake. Further understanding of the serotonergic mechanisms affecting food consumption, in addition to improving animal production, can lead to effective serotonin-based drug treatments to help modulate appetite in humans. The purpose of this review is to examine the research conducted on the role of the serotonergic system (except for the interference of its effect with other systems) in the process of obtaining food. In the present study, according to PRISMA guidelines, articles related to the topic were identified using a systematic search of standard keywords in reliable databases such as Web of Science, Scopus, Science Direct, PubMed, Springer, Google Scholar, and Elsevier in the period of 1990-2022. In order to obtain more studies, the list of sources of these articles was examined. Finally, 40 articles that met all the conditions for entering the analytical stage were examined. Based on the findings of these studies, serotonin in birds and mammals reduces food intake. Serotonin reuptake inhibitor compounds also cause hypophagia and serotonin receptor agonists and antagonists have different effects on the appetite process. It also seems that 5HT1A, 5HT1B and 5HT2C receptors have the most interaction in the process of appetite modulation. Considering the diversity of serotonin receptors and the distribution of this system in different central and peripheral areas in order to know its role in regulating food intake, it is necessary to carry out more research in this field.
‎

Serotonin (5-HT) plays an underpinning role in appetite regulation and the opioid system has a role in the modulation of the ingestion behavior in birds. The current survey was aimed to evaluate the effect of opioid receptors on serotonin-induced hypophagia in neonatal broilers. During experiments, food-deprived chickens received intracerebroventricular (ICV) injection and thereafter, the cumulative food intake was measured after 30, 60, and 120 minutes. In experiment 1, to determine the effective dose of serotonin, the control solution and the various doses of serotonin (2.5, 5, and 10 μg) were administered to birds. In the second experiment, groups received not only the control solution, but also an effective dose of serotonin (10 µg), µ-opioid receptor antagonist (β_FNA, 5 µg), and a co-injection of β_FNA (5 µg) and serotonin (10 µg), respectively. The next experiments were similar to the second experiment, however, in place of β_FNA, the antagonist of κ- opioid receptor (nor_BNI, 5 µg), the δ- opioid receptor antagonist (NTI, 5 µg), and the agonist of µ opioid receptor (DAMGO, 62.25 pmol) were used in experiments 3, 4, and 5, respectively. The results showed a dose-dependent hypophagic impact of serotonin. This effect was attenuated by β_FNA; however, nor_BNI and NTI had no effect. Furthermore, the diminishing effect of serotonin on food consumption in chickens was strengthened following DAMGO administration (p < 0.05). According to the results, the hypophagic effect of serotonin is possibly mediated through µ opioid receptors in neonatal broilers.