Compensatory Secretion Of Adrenal Androgen After Castration

Testes and adrenal glands are the sources of androgen in male animals.After surgical castration,hypothalamic-pituitary-testicular axis dysfunction,resulting in a rapid decrease in testicular testosterone.Consequently,in the compensatory effect,the pituitary ACTH is secreted in large quantities and drains into the adrenal cortex that stimulates the adrenal gland to produce more dehydroepiandrosterone(DHEA).However,whether the adrenal gland plays a compensatory role during immunocastration remains unknown.Therefore,the purpose of this study was to investigate the causes of compensatory secretion of adrenal androgen in immunocastrated rats and goats.Our previous studies on the immunocastration of male rats and goats showed that the immunocastration using the KISS1 gene vaccine resulted in a decrease luteinizing hormone(LH),testosterone,and other reproductive hormones,and cause atrophy of testis and spermatogenic cells,showing a good castration effect.In this study,rats and goats were used as experimental animals.For rat experiment,thirty-six 8-week-old SD male rats were randomly divided into three groups: surgical castration(SC),PVAX-B2L-Kisspeptin-54 asd(PBK)vaccine immunized and PVAX-asd empty plasmid treated(control,C).The PBK group and control group rats received(100 ?g/dose)PBK DNA vaccine and PVAX-asd empty plasmid via the intramuscular route.The related hormones(ACTH,DHEA,and CORT)were detected by enzyme-linked immunosorbent assay(ELISA),change in adrenal tissue structure was observed by microscope,and the gene expression of the adrenal gland and its upstream tissues were detected by fluorescence quantitative polymerase chain reaction(qPCR).In the goat experiment,fifteen 5-month-old male Yiling goats were randomly divided into three groups: surgical castration(SC),PBK-asd(PBK)vaccine immunized and PVAX-asd empty plasmid treated(C).The vaccine was given intramuscularly(1mg/dose)and boosted twice at 21 days interval.The levels of ACTH and DHEA hormones were detected after the castration effect was confirmed.Transcriptome sequencing was used to study the transcription level of adrenal gland tissues.The main research results are as follows:1.The hormone detection results in rats showed that serum ACTH and DHEA significantly increased in the surgical castration group at week 6(P<0.05),and CORT significantly increased at week 4(P<0.05),which lasted until the end of the experiment.In the immunocastration group,significant increases in ACTH and CORT were detected at week 4(P<0.05)and DHEA at week 6(P<0.05),and remained at a high level thereafter.2.Quantitative PCR was used to detect the m RNA expression of genes in the hypothalamus,pituitary and adrenal tissues of rats.The results showed that the relative expressions of hypothalamus CRH and KISS1,pituitary CRHR and POMC,and adrenal MC2 R in the immunocastration group were significantly increased compared to the control group(P<0.05).Whereas,the expression of hypothalamic AR and GPR54,pituitary LH,adrenal LHR were significantly decreased in this group(P<0.05).The relative expressions of hypothalamic CRH,KISS1 and GPR54,pituitary CRHR,POMC and LH,adrenal MC2 R and LHR were significantly increased in surgical castration group(P<0.05).The relative expression levels of AR and LHR in hypothalamus were significantly decreased in surgical castration group(P<0.05).No expression of GPR54 gene in adrenal gland was detected.3.The serum hormone results in male Yiling goats showed that ACTH was significantly increased in the surgical castration group at week 6(P<0.05),and significantly increased in the immunocastration group at week 8(P<0.05).At weeks 8 and 10,the serum DHEA levels were significantly increased in the surgical castration group and immunocastration groups compared to the control group(P<0.05).4.Transcriptome sequencing was performed on the adrenal tissues of Yiling goat treated by different castration methods.The results showed that 2,329 differentially expressed genes were screened from PBK vs C,of which 664 were up-regulated and 1,665 were down-regulated.Similarly,from SC vs C group,1,834 differentially expressed genes were screened,among which 193 were up-regulated and 1,641 were down-regulated.In the GO enrichment analysis,842 functional regions were enriched by the different genes of PBK vs C,and 1,183 functional regions were enriched by the different genes of SC vs C.In the KEGG enrichment analysis,33 biological pathways were obtained by the enrichment of PBK vs C differential genes,and 39 biological pathways were obtained by the enrichment of SC vs C differential genes.5.By screening the differentially expressed genes sequenced in the adrenal transcriptome of Yiling goat,qPCR verification was conducted on five genes that may be related to adrenal androgen secretion.It was found that the expressions of CDH2 and SDK1 genes in surgical castration and immunocastration groups were significantly lower than those in the control group(P<0.05),and the expression of the SALL1 gene was significantly higher than that in the control group(P<0.05).Above all,these results indicate that the secretion of adrenal androgens increased after the suppression of testicular androgens,suggesting that the adrenal glands may play a compensatory role.In this study,the KISS1 gene receptor(GPR54)expression in adrenal glands of rats was not detected,indicating that adrenal tissues were not directly affected by PBK immunocastration vaccine.After castration,the hormone secretion and gene expression of the hypothalamic-pituitary-adrenal(HPA)axis were increased and the activity of the HPA axis was enhanced,indicating that the function of the adrenal gland was regulated by the hypothalamus and the pituitary gland.In the adrenal transcriptome sequencing of castrated goats,many differentially expressed genes were screened out and enriched into multiple pathways,among which some differentially expressed genes such as CDH2,SDK1 and SALL1 may be involved in the compensatory secretion of adrenal androgens.