*4.4. Intestinal Morphology*

The intestinal morphology analysis was performed according our previously described methods [2].

#### *4.5. Intestinal Antioxidant Parameters and Inflammatory Cytokines*

About 1 g of each mucosal sample was homogenized at a ratio of 1:9 (weight/volume) with ice-cold PBS. Homogenate was centrifuged at 3200× *g* for 10 min at 4 ◦C to obtain supernatant; Bradford method was used to determine the supernatant protein concentration. The antioxidant parameters and inflammatory cytokines were measured with corresponding assay kits (Nanjing Jiancheng Bioengineering Institute, Nanjing, China).

#### *4.6. Free Radical Scavenging Activities*

DPPH, ABTS, O2<sup>−</sup>, and OH− scavenging activities were evaluated by following the methods described in another study [20].

#### *4.7. Gene Expression Analysis*

Total RNA extraction, cDNA reverse transcription, and real-time polymerase chain reaction analysis were done according to our previous described methods [47]. The primers are shown in Table 3. The relative mRNA expression was calculated by 2−ΔΔCt method.

**Table 3.** Primers for real-time PCR.


#### *4.8. Western Blot Analysis*

The procedures of the Western blot assay were according to the description of Alhaithloul et al. [37].

## *4.9. Statistical Analysis*

The individual rat was regarded as the experiment unit, SAS 2003 (version 9.1, SAS Institute Inc., Cary, NC, USA) was used to analyze the statistic. Duncan's multiple range test was used to check the variance among the groups, and the differences were considered significant at *p* < 0.05.

**Author Contributions:** R.L. and Z.Z. designed the experiment. R.L. did the manuscript writing. Q.C. and L.W. were involved in experimental analysis and data collection. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the scientific research start-up funds of Guangdong Ocean University (R18005).

**Institutional Review Board Statement:** The study was approved by the Animal Care and Use Committee of Guangdong Ocean University (SYXK-2018-0147, 2018).

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Acknowledgments:** Special thanks to Yiqi Lu, who provided assistance in rat management.

**Conflicts of Interest:** The authors declare no conflict of interest.
