Effects of red orange and lemon extract (RLE) supplementation on NPY pattern in gastro-enteropancreatic system of goat kids

Over the last decades extensive studies have been done to search for natural alternatives to in-feed antibiotics in farm animals, and plant compounds have been identified to have great potentials [1]. Among them, a growing interest in the consumption of anthocyanin-rich food has been observed. Anthocyanins (ANTs), which belong to the flavonoid family, are water soluble polyphenolic pigments widespread in the plant kingdom. Several researches highlighted the numerous health benefits of ANTs, like antioxidant, anti-inflammatory and immunostimulant properties [2]. Although many of the biological effects of polyphenols are well known, only a limited number of studies have addressed the influence of their supplementation in ruminant diet, focusing primarily on anti-oxidant capacity. This study aimed to examine the effect of a diet supplemented with a standardized powder extract, Red (blood) orange and Lemon Extract (RLE), rich in flavanones, anthocyanins and other polyphenols, on the neuropeptide Y (NPY) distribution in gastro-entero-pancreatic system of goat kids. We decided to focus our attention on NPY because in mammals this peptide is widely distributed in both the central and the peripheral nervous systems and it has been functionally implicated in the regulation of feeding behavior and gastrointestinal tract motility [3]. The research was approved with Protocol PG/2019/0028161 by the University of Naples Federico II. Sixty kids of Saanen bred, both males and females, after colostrum administration, were randomly divided into two homogenous groups of 30 kids each. The two experimental groups were fed for 40 days with: (1) standard diet made of hay (100 g) and kids starter (150 g) (CTRL group); (2) standard diet supplemented with RLE (90mg/kg) (TRT group). We carried out immunohistochemical analyses on samples of abomasum, duodenum (removed 4 cm from the pyloric sphincter) and pancreas collected from the two experimental groups. For the first time, we document that NPY is widely distributed in the gastro-entero-pancreatic tract of goat kids. Immunoreactive cells were detected in scattered cells of the epithelium and in typical varicosity in the muscular layer of the abomasum; in neuroendocrine cells and varicose fibers of the muscular layer in the duodenum and at the margin of pancreatic islet cells. The wider distribution was observed in the duodenum, and to a less extent in the pancreas and abomasum. In order to evaluate if RLE supplementation feed cn affect NPY's distribution, we quantified the number of immunoreactive cells in all the three different selected segments. Remarkably, we described a strong significant increase of NPY immunolabeled cells in the abomasum and pancreas (p>0.0001) and a non-significant increase in the duodenum (p < 0.05) of TRT group compared to CTRL group. Our findings can be useful for further researches on the interaction between neuropeptides and polyphenols aiming to reduce antibiotic use and prevent antimicrobial resistance.