Effects Of Vitamin A On Reproduction Performance And Immune Function Of The Male Mice Infected With Pseudorabies Virus

The objective of the present study was to evaluate the protective effects of Vitamin A levels on the reproductive performance of the male mice challenged with Pseudorabies Virus(PRV).120 First-class Kunming male mice with the initial age of 32 days were randomly allocated to eight groups:Five vitamin A supplemental levels(0IU,4000IU,10000IU,25000IU,50000IU/kg) treatment groups with challenged PRV,and three vitamin A supplemental levels(0IU,4000IU,10000IU/kg) with challenged PBS as control groups.PRV infection were conducted after 11 weeks adaptation to these diets.Samples collected on 7th and 14th days post-infection were used to determine the liver retinol content by HPLC,organ index,spermatozoa density, teratospermia ratio,serum immune globulin(IgG,IgA,IgM) secretion by R/A,cytokine (IL-1β,IFN-γ,IL-10) secretion by ELISA,and the testis tissue mRNA expression of the toll-like receptor 3,7 and 9(TLR3,TLR7 and TLR9) by RT-PCR.1,The liver retinol contents of the PRV infected mice were significantly lower than the control groups.Vitamin A supplemental level elevated the liver retinol content(P＜0.05),0 IU/kg and 4 000IU/kg groups were similar(P＞0.05),but were significantly lower than the 10 000,25 000,50 000 IU/kg groups.Dose-related increase of the liver retinol content to the dietary supplemental vitamin A levels was observed in the 10 000,25 000,50 000 IU/kg groups(P＜0.05).2,The mortality of the PRV infected mice were lower as the increasing VA supplemental level.0 IU/kg group had the highest mortality as 37.5%,whereas it was only 18.8%in the 25 000IU/kg and 50 000IU/kg groups.There was no statistical difference among each group(P＞0.05).3,Compared with control groups,PRV infected significantly decreased the spermatozoa density and elevated the teratospermia ratio(P＜0.05),but did not affect organ index(P＞0.05).Increasing vitamin A supplemental levels influenced spermatozoa density,organ index and teratospermia ratio of the mice infected with PRV.On 7 and 14 days post-infection,the spermatozoa density and organ index were similar in among 10 000,25 000 and 50 000 IU/kg groups(P＞0.05),but were higher than 0 IU/kg group which did not differ from 4 000IU/kg group(P＜0.05).Regression analysis identified that greatest spermatozoa density and lowest teratospermia ratio could be achieved at the supplemental level of 45 000 and 32 500 IU/kg on 7^th day post-infection,or 40 000 IU/kg and 31 250 IU/kg on 14^th day post-infection respectively.4,The serum IL-1βand IFN-γconcentrations were elevated in the PRV infected mice than the PBS infected mice(P＜0.05),whereas the IL-10 concentration were similar(P＞0.05).Dietary supplemental vitamin A levels affected the serum IL-1β,IFN-γand IL-10 concentrations.On 7^th and 14^th days post-infection,the concentrations of IL-1βand IFN-γof 10 000,25 000and 50 000 IU/kg groups were lower than 0 IU/kg groups (P＜0.05),and 50 000 IU/kg group was low than the 10 000 IU/kg group(P＜0.05). However,the effects of vitamin A levels on serum IL-10 concentration had an oppositely way,whose concentration was greater as the increasing vitamin A supplemental level(P＜0.05).5,The serum concentrations of IgG and IgA were higher in the PRV infected mice than the PBS infected mice(P＜0.05),but the IgM secretion were similar(P＞0.05).The serum concentrations of IgG,IgA and IgM were influenced by different vitamin A supplemental levels.The concentrations of IgG,IgA and IgM of the 0 IU/kg group was lower than other groups,which gradually increased in a dose-related way as the higher vitamin A supplemental level(P＜0.05),25 000 IU/kg and 50 000 IU/kg groups were not different(P＞0.05),but was higher in 50 000 1U/kg group than the 4 000 IU/kg group(P＜0.05).6,Compared with the control groups challenge with PBS,the testis tissue mRNA expressions of TLR3,TLR7 and TLR9 of the PRV-challenge mice were up-regulated(P＜0.05),and the mRNA expressions of those TLRs were down-regulated as the increasing vitamin A supplemental levels(P＜0.05).On 7^th and 14^th days post-infected,the mRNA expressions of TLR3,TLR7 and TLR9 in 0 IU/kg was higher than 10 000,25 000 and 50 000IU/kg groups(P＜0.05),and 25 000 and 50 000IU/kg groups was lower than the 10 000IU/kg group(P＜0.05).These results demonstrated that:1,Marginal vitamin A deficit would contribute to the decreased immune function and reproductive performance.Lower liver retinol content and spermatozoa density,as well as increased teratospermia ratio and mortality were observed due to PRV infection.2,Upon PRV infection,higher vitamin A requirement than normal should be achieved to guarantee the reproductive performance.3,Increased dietary vitamin A supplemental level could stimulate the serum immuneglobulins secretion to enhance the humoral immunity of the PRV infected mice, thus improve the recovery of the reproductive performance of the mice suffered PRV infection.4,Increased dietary vitamin A supplemental level could decrease the serum pro-inflammatory factors to down-regulated the testis TLRs expression,thus protect the spermatozoa quality from exogenous virus invading.