Relationship Between Testosterone and Dihydrotestosterone With Microbiota and Toll-Like Receptor Protein Localization in the Male Pig Reproductive Tract Prior to and Post Pubertal Attainment

Our lab previously demonstrated shifts in relative abundance of bacterial communities between pre- and post-pubertal boar reproductive tissues. Hormones such as testosterone (T) and dihydrotestosterone (DHT) play important roles in sexual development of males. Expression of toll-like receptors (TLRs) in various tissues has been shown to be influenced by hormones in rodents and humans. Therefore, the objective of the current study is to relate the change in bacterial abundances in pre- and post-pubertal boars and expression of TLRs (TLR1, TLR2, TLR4, TLR5, and TLR6) mRNAs in pre-pubertal boars to androgen (T and DHT) secretion. Additionally, an objective is to immunolocalize TLR4 in pre- and post-pubertal boar testes and epididymal tissues. Intact reproductive tracts of crossbred boars (n = 4 pre-pubertal and n = 7 post-pubertal) were harvested and tissues (testis, epididymis, prostate, seminal vesicle, and bulbourethral gland) were stored at -80 degrees C for RT-qPCR and fixed in 4% paraformaldehyde prior to paraffin embedding and sectioning. From each boar, sterile swabs and plasma samples were collected for microbiome analysis and hormonal concentrations, respectively. Plasma concentration of DHT were quantified using a competitive ELISA and plasma T concentrations were determined using chemiluminescence. Data were analyzed using PROC CORR in SAS 9.4. Significant correlations between T concentrations and relative abundance of the phyla Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria were observed between specific reproductive tissues of pre- and post-pubertal boars. There were no correlations between phyla relative abundances and DHT (P > 0.10). In pre-pubertal boar seminal vesicles, DHT concentration was significantly correlated with expression of both TLR2 and TLR4. Dihydrotestosterone concentrations had a tendency to be correlated with expression of TLR2 in the pre-pubertal boar testes. Immunolocalization revealed the presence of TLR4 in the interstitial compartment of the testes and in epithelial cells of the epididymal ducts. Immunolocalization of TLR4 appeared more intensive in post-pubertal boar tissues. Based on these findings, TLRs exist in specific locations within the reproductive organs of pre- and post- pubertal boars and their TLR expression as well as distinct bacterial abundance within specific tissue share a relationship with steroid hormone concentration suggesting a control mechanism that warrants further investigation.

Name thesis:degree_name

Master of Science

Discipline thesis:degree_discipline

Physiology of Reproduction

Grantor

Texas A&M University

Year dc:date.issued

2025

Author dc:creator

• Ognibene, Olivia Josephine 2001-

Advisor dc:contributor.advisor

• Poole, Rebecca

Committee members dc:contributor.committeemember

• Welsh, Jane
• Luense, Lacey
• Wiegert, Jeffrey

• Biology, Animal Physiology

Language dc:language.iso

English

Handle dc:identifier.uri

https://hdl.handle.net/1969.1/1598857

OAI record oai:identifier

https://oaktrust.library.tamu.edu/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Aoaktrust.library.tamu.edu%3A1969.1%2F1598857