شیبا یوسفوند

During the modification of several races, which has been done on chickens, there have been several changes in the function of neural pathways and receptor density involved in the control of food intake and appetite. Melanocortin system and its receptors are involved in the central regulation of nutritional behaviour and energy balance. Therefore, this study was designed to investigate the role of this system in the central control of food and water intake in birds.

The present study aimed to evaluate the role of MCR3 and MCR4 receptors in controlling the food and water intake in birds.

This work was performed on 48 Ross 308 broiler chicks through two experiments (each experiment in four groups). Primarily, stereotaxic surgical guide cannula was implanted in the chickens. Subsequently, in the first experiment, the chickens were divided into the four following groups: the control solution, 0.2, 2, and 10 nmol/5µl of SHU9119 (Non-selective antagonist of MCR3 and MCR4 receptors) In the second experiment, the chickens were also divided in four groups: the received control solution, 0.2, 2, and 10 nmol/5µl of MCL0020 (Selective MCR4 receptor antagonist) via intracerebroventricular (ICV) injection. Afterwards, cumulative food and water intake were measured at 30, 60, 90, 120, 150, and 180 minutes after the injection.

The results of this study showed that ICV injection of SHU9119 and MCL0020 increased cumulative food intake (P>0.05), but did not affect cumulative water intake (P<0.05).

According to the findings herein, central melanocortin system is one of the systems involved in central control of food intake in birds.

Imbalance of body fluids can cause numerous problems and diseases including ascites in poultry. Therefore, identifying the mechanisms involved in controlling water intake can help to better understand the pathophysiology of related diseases. NPY is one of the neuropeptides involved in central control of water intake. When deprived of water, the mRNA synthesis of this neuropeptide increases in the hypothalamus. So, this study examines the role of NPY1 and NPY2 receptors in central control of water intake. Two series of experiments were conducted in this study. In the first and second experiments, male broiler chickens respectively received 10 μl of Evans Blue, 20 μg, 10 μg, 5 μg and 2.5 μg of B5063 and SF22 (receptors antagonists NPY) by ICV injection. Then cumulative water intake was measured at 90 and 180 minutes after injection. The results showed that ICV injection of B5063 (20, 10, 5 and 2.5 μg) resulted in reduction in water intake compared with the control group (p < 0.05), while none of the SF22 doses had an effect on cumulative water intake compared to the control group (P>0.05). The results of these experiments showed that the effect of NPY on water intake may be conducted through NPY1 receptor.

Disorders of body fluid balance lead to metabolic problems and diseases such as ascites in poultry, which require studies on the clarification of involved mechanisms in water intake. The effect of insulin and somatostatin on water intake in 5-day male broiler chickens (Ross 308) was investigated.

Two experiments were conducted. In the first one, 10, 20 and 40 ng of insulin and in the second one, 0.5, 1 and 2 nM of somatostatin were injected to chicken via intracerebroventricular (icv) injection. Control group received Evans blue in both experiments. Accumulated water intake at 90 and 180 minutes after injection was measured.

The doses of 10, 20 and 40 (ng) of insulin at 90 min after injection, showed a significant reduction in water intake compared with control group (p < 0.05). In 180 minutes after injection of insulin 20 ng, reduction of water consumption was retained but doses of 10 and 40 ng did not affect water consumption. The group that received 20 ng of insulin showed a significant reduction on water intake 180 minutes after injection compared with groups of 10 and 40 ng (p < 0.05). Somatostatin 0.5nM did not affect accumulated water intake in 90 and 180 minutes after injection compared with control group. However, somatostatin 1 and 2 nM significantly reduced water intake in 90 minutes after injection compared to the control group (p < 0.05). In 180 minutes after injection of somatostatin 2 nM, reduction of water consumption was retained but the dose of 1nM did not affect water consumption. Doses of 0.5, 1 and 2 nM of somatostatin significantly reduced water intake in a dose-dependent manner (p < 0.05).

Somatostatin and insulin reduced water intake in neonatal chickens.

Introduction Arcuate nucleus (ARC) is an aggregation of neurons in the basal hypothalamus, is thought to play a pivotal role in the integration of signals regulating food intake. Given the important role of hypothalamus in regulating of food intake, the aim of this review study was discussion on the mediating role of the ARC in feeding behaviour.
Materials and Methods In 2016, in this study by searching related articles published in valid scientific databases such as PubMed, Web of Science, Scopus, Elsevier, Springer, Science Direct, and SID with standard keywords and reference. Lists of identified articles were reviewed for the additional articles during 1998 to 2016.
Results These studies reported that the arcuate nucleus includes several populations of neurons that contain neuropeptide Y, agouti-related peptide, GABA, and αMSH. These neurons, in the most ventromedial part of the nucleus, project strongly to the other nuclei of hypothalamus, and are important in the regulation of feeding behaviour and increasing or decreasing of food intake. The ARC is available to peripheral signals of energy balance, via median eminence, because this part of the brain is not protected completely by the blood brain barrier.
Conclusion Based on the literature, the ARC is the part of brain where some neurotransmitters exert the most potent orexigenic or anorexigenic effects in mammals and birds. Food intake is inhibited by leptin, insulin, αMSH, and serotonin and activated by NP Y, Agrp, NO F/Q, and GABA. However, a few neurotransmitter such as ghrelin has a dual function, ghrelin stimulates feeding in mammals, although it attenuates food intake in birds.

Due to the effects of some pollutants on the thyroid gland function and to assess the effects of hypothyroidism on some blood biochemical parameters of common carps, this study was conducted. Fishes were divided into four groups of 30 each. The groups were treated by zero (control group), 3, 9 and 27 mg/L of propylthiouracil in water for one month. After 1 month, blood was taken from 15 fishes from each group and their weight, serum thyroid hormones, triglycerides, total cholesterol, HDL-c, LDL-c, glucose and serum urea urea were measured. For the reminder, the drug application was discontinued and the other halves of the fish were examined one month later, in the similar manner to the previous stage. In stage 1 (after one month) in comparison between different groups, thyroid hormones did not show significant difference (p>0.05), but in the second stage, T4 level was lower in the treatment groups in comparison with the control (p<0.05). T3 level in 3 and 9 mg/l groups were higher than 27 mg/L group and the control (p<0.05). The triglycerides level was higher in 3 and 9 mg/L groups compared to control group (p<0.05). HDL-c in the second stage in 3 mg/L group was higher than the control group and 27mg/L group (p<0.05). Glucose in the second stage was significantly lower in 9 mg/l group in comparaison with the control group (p<0.05). Urea also increased in the treated groups in comparison with the control (p<0.05). Accordingly, it is concluded that thyroid hormones had responded to the treatment with delay and their changes have affected the studied variables dependently.