Graduate Studies

 

First Advisor

Amy T. Desaulniers

Date of this Version

5-2024

Document Type

Article

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Veterinary Science

Under the supervision of Professor Amy T. Desaulniers

Lincoln, Nebraska, May 2024

Comments

Copyright 2024, Nicole E. Nordell. Used by permission

Abstract

Termed lactocrine programming, the consumption of maternal milk through nursing enhances development of neonatal organs, including the testis. For example, nursed males develop larger testes with more Sertoli cells compared with formula-fed males. Colostrum and mature milk contain dynamic bioactive molecules that support the development of offspring. Extracellular vesicles (EVs) are a class of natural nanoparticles that are abundant in milk and contain bioactive cargos (e.g., proteins and miRNAs). The objective of this study was to assess the effect of sow milk and sow milk-derived EVs (mEVs) on testicular development and endocrine function of neonatal boars after 24 hours of treatment. Diets consisted of 1) sow milk (Milk; n = 7) containing native EVs; 2) ultrasonicated sow milk (US; n = 7) in which EV content and miRNA cargo are reduced; 3) milk replacer (MR; n = 8), which lacks bioactive EVs; or 4) MR supplemented with sow mEVs (EVMR; n = 8). Histological analysis of testes revealed that EVMR-fed boars had a greater number of seminiferous tubules (per field) compared with all other treatments. Additionally, EVMR-boars had an increased average and total seminiferous tubule area compared with MR-fed boars. Leydig cell area was the greatest in MR-fed boars, suggesting an effect on steroidogenesis. Sertoli cell counts were greatest in milk-fed boars and germ cell counts tended to be greatest in EVMR boars. Testicular proteomics revealed that 1,043 testicular proteins were differentially abundant between milk and MR-fed boars, 852 proteins differed between EVMR and MR-fed boars, and 551 proteins differed between milk and US groups. Notably, key Sertoli cell markers (e.g., AMH, SOX-9, and GATA-4) were affected by EVMR versus MR treatment. Gene ontology analysis revealed that mEVs affected biological processes in the testis related to apoptosis, metabolic processes, vesicle-mediated transport, protein production, cell migration, immune processes, and cell cycle. Endocrine changes included elevations in serum concentrations of follicle-stimulating hormone, testosterone, and androstenedione (greatest in US-boars). These results suggest that maternal milk and milk EVs help drive lactocrine programming of the neonatal boar testis.

Advisor: Amy T. Desaulniers

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