Inflammation is a protective response of the immune defense system and inflammatory response could be regulated by autophagy. β-Carotene has shown antiinflammatory potential. However, whether β-carotene could alleviate rat intestinal inflammation by modulating autophagy and its anti-inflammation underlying mechanisms remain unknown. In this study, we found that β-carotene significantly reduced (p < .05) the production of nitric oxide (NO), prostaglandin (PG)E2, tumor necrosis factor (TNF)-α, and interleukin-1β (IL-1β) levels by the Griess reaction and enzymelinked immunosorbent assay (ELISA), and we found that β-carotene significantly suppressed (p < .05) the mRNA expression levels of IL-1β and TNF-α by RT-PCR. In addition, H&E staining revealed that β-carotene could improve intestinal morphology and cell morphology. Furthermore, the levels of signaling proteins of microtubule-associated protein light chain 3 (LC3), AKT, Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3), nuclear factor-kappa B (NF-κB), and c-Jun N-terminal kinase (JNK)/p38 mitogen-activated protein kinase (MAPK) were detected by Western blot analysis. We found that β-carotene significantly attenuated (p < .05) the related signaling proteins activated by lipopolysaccharide (LPS) stimulation in rats. Moreover, this conclusion was also verified in intestinal epithelial cell (IEC)-6. 3-Methyladenine (3-MA) is widely used as inhibitor of autophagy via its inhibitory effect on class III PI3K. Simultaneously, pretreatment of 3-MA suppressed the inhibiting effects of β-carotene on the related signaling proteins. This study demonstrates that β-carotene could attenuate the LPS-induced intestinal inflammation in rats via modulating autophagy and regulating the JAK2/STAT3 and JNK/p38 MAPK signaling pathways. We also found the same phenomenon when we verified the results with the IEC-6 cells. These findings provide new insights into improving the nutritional value of basic diets and enhancing immune performance. Practical applications β-Carotene is a generally acknowledged natural carotenoid nutrient that exhibits provitamin A activity, and it is widely found in fruits or vegetables. Our study provide a new insight into the anti-inflammatory mechanism of β-carotene. Treatment with β-carotene can be used for the beneficial effect against LPS-induced inflammation 2 | MATERIAL S AND ME THODS All experiments involving animals in this study were approved by the Institutional Animal Care and Use Committee, Jilin Agricultural University (No. 201705001). All efforts were made to alleviate animal suffering. damage. This study not only lays the foundation for the related research on the antiinflammatory properties of β-carotene in vitro and in rat models, but also holds important significance in the field of food.

Objective: Weaning is an important stage in the life of young mammals, which is associated with intestinal inflammation, gut microbiota disorders, and even death. β-Carotene displays anti-inflammatory and antioxidant activities, which can prevent the development of inflammatory diseases. However, whether β-carotene can affect intestinal microbiota remains unclear. Methods: Twenty-four piglets were distributed into four groups: the normal suckling group (Con), the weaning group (WG), the weaning+β-carotene (40 mg/kg) group (LCBC), and the weaning+β-carotene (80 mg/kg) group (HCBC). The serum, jejunum, colon, and faeces were collected separately from each group. The effects of β-carotene on the phenotype, overall structure, and composition of gut microbiota were assessed in weaning piglets. Results: The results showed that β-carotene improved the growth performance, intestinal morphology and relieved inflammation. Furthermore, β-carotene significantly decreased the species from phyla Bacteroidetes and the genus Prevotella, and Blautia, and increased the species from the phyla Firmicutes and the genera p-75-a5, and Parabacteroides compared to the WG group. Spearman's correlation analysis showed that Prevotella and Blautia were positively correlated, and Parabacteroides and Synergistes were negatively correlated with the levels of interleukin-1β (IL-1β), IL-6, and tumour necrosis factor-α (TNF-α), while p-75-a5 showed negative correlation with IL-6 in serum samples from piglets. Conclusion: These findings indicate that β-carotene could alleviate weaning-induced intestinal inflammation by modulating gut microbiota in piglets. Prevotella may be a potential target of β-carotene in alleviating the weaning-induced intestinal inflammation in piglets.

Weaning may cause oxidative injury, immune response impairment, apoptosis and other injuries in piglets. Oxidative and endoplasmic reticulum stress (ERS) can elicit inflammatory responses, and persistent oxidative and ERS also may lead to apoptotic cascades, which is associated with the pathogenesis of multiple diseases. β‐carotene, a natural carotenoid, has potential anti‐inflammatory and antioxidant functions. However, the effect of β‐carotene on apoptosis in weaned piglets and the detailed molecular mechanism remain unclear. In this study, we found that β‐carotene decreased malondialdehyde (MDA) levels and increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) in piglet serum. β‐carotene could inhibit the mRNA levels of caspase‐3 significantly, but had no significant inhibitory effect of the mRNA levels of caspase‐9 and caspase‐12 in the piglet jejunum. In addition, β‐carotene decreased the activation of GRP78, CHOP, and JNK/p38 MAPK and the ratio of Bax/Bcl‐2. Furthermore, β‐carotene had a significant influence on the activation of ERS and apoptosis‐related signals in TG‐induced IPEC‐J2. In the present study, β‐carotene pre‐treatment attenuated the ratio of Bax/Bcl‐2 and prevented TG‐induced increases in the level of PERK‐CHOP and IRE1‐JNK/p38 MAPK pathway activation in a dose‐dependent manner. Overall, these findings indicate that β‐carotene may protect weaning‐induced apoptosis through inhibiting ERS.

It is well known that zinc ion (Zn 2+ ) can regulate the biological activity of growth hormone (GH). However, until now, the mechanism by which Zn 2+ regulates GH biological activity remains unclear. In the current study, we first performed molecular docking between Zn 2+ and porcine GH (pGH) using computational biology. We then explored the effect of Zn 2+ on the GH signaling ability in the cell model expressing porcine growth hormone receptor (GHR). It was found that the phosphorylation levels of Janus kinase 2, signal transducers and activators of transcription 5/3/1, and GHR increased significantly under Zn 2+ treatment, indicating that Zn 2+ can enhance the signaling ability of GH/GHR. On this basis, we further explored how Zn 2+ regulates the biological activity of GH/GHR. The results showed that downregulation and turnover of GHR changed under Zn 2+ /pGH treatment. Zn 2+ enhanced the membrane residence time of pGH/GHR and delayed GHR downregulation. Further investigation showed that the internalization dynamic of pGH/GHR was changed by Zn 2+ , which prolonged the residence time of pGH/GHR in the cell membrane. These factors acted together to upregulate the signaling of GH/GHR. This study lays a foundation for further exploration of the biological effects of Zn 2+ on GH. K E Y W O R D S GHR downregulation, growth hormone receptor, porcine growth hormone, signal transduction, Zn 2+ SUPPORTING INFORMATION Additional supporting information may be found online in the Supporting Information section. How to cite this article: Li R, Hui J, Luo G, et al. Zinc ions increase GH signaling ability through regulation of available plasma membrane-localized GHR. J Cell Physiol.