Leydig Cells in Immunocastrated Polish Landrace Pig Testis: Differentiation Status and Steroid Enzyme Expression Status

Abstract

Porker immunocastration against gonadoliberin (GnRH) secretion has been utilized since 2009; however, consumers are still skeptical of it. This is due to not having full information available on the problem of a boar taint, as well as a lack of research on morphological and molecular changes that may occur in the animal reproductive system and other body systems. The present study aimed to explore the functional status of steroidogenic Leydig cells of the testicular interstitial tissue in immunocastrated Polish Landrace pigs. Analyses were performed using Western blot, immunohistochemistry for relaxin (RLN), insulin-like 3 protein (INSL3), pelleted growth factor receptor α (PDGFRα), cytochrome P450scc, 3β- and 17β-hydroxysteroid dehydrogenases (3β-HSD, 17β-HSD), cytochrome P450arom, and 5α-reductase (5α-RED). Immunoassay ELISA was used to measure the androstenone, testosterone, and estradiol levels in the testis and serum of immunocastrates. We revealed disturbances in the distribution and expression of (i) RLN, indicating an inflammatory reaction in the interstitial tissue; (ii) INSL3 and PDGFRα, indicating alterations in the differentiation and function of fetal, perinatal, or adult Leydig cell populations; (iii) P450scc, 3β-HSD, 17β-HSD, P450arom, and 5α-RED, indicating disturbances in the sex steroid hormone production and disturbed functional status of Leydig cells; as well as (iv) decreased levels of androstenone, testosterone, and estradiol in testicular tissue and serum, indicating the dedicated action of Improvac to reduce boar taint at both the hypothalamic–hypophysis–gonadal axis and local level (Leydig cells). In summary, our study provides a significant portion of knowledge on the function of Leydig cells after immunocastration, which is also important for the diagnosis and therapy of testis dysfunction due to GnRH action failure and/or Leydig cell differentiational–functional alterations.

Effect of immunocastration using Improvac on the regulation of adiponectin and leptin in the testes of Landrace boars

“…Comparative studies in Large White and Meishan pigs have reported differences in the adipokine expression correlated positively or negatively, depending on adipokine type, with the fat thickness (2). Moreover, the decreased levels of androstenone in immunocastrated Landrace pigs (29) tend to confirm the decreased adiponectin and leptin signaling and increased cholesterol levels observed in the present study. Adipokines and cytokines of the adipose tissue are regulated by androgens and estrogens.…”

“…Our previous studies have revealed that leptin expression in Leydig cells of seasonal breeders is independent of their reproductive activity (27). Our additional findings demonstrated that in GnRH vaccinated Landrace pigs, the replacement of fetal and perinatal Leydig cell populations with the adult cells seems to be impaired with significant Leydig cell shrinkage (29). All of these events are closely linked to the blockage of sex steroid secretion by the GnRH vaccine.…”

“…concen-tration, motility, or morphology (8). Therefore, in nonvaccinated males, spermatogenesis was not fully halted (29). This is possibly partially due to the disturbed expression of adiponectin signaling in both interstitial tissue and the spermatogenic epithelium (mainly in elongated spermatids).…”

“…Our recent studies have demonstrated that inflammation of testicular tissue occurs together with incomplete spermatogenesis ablation in immunocastrated Landrace boars (29). The adiponectin/leptin ratio is a functional biomarker of adipose tissue dysfunction, inflammation, metabolic syndrome, or obesity (12).…”

Porcine reproductive and respiratory syndrome virus infects the reproductive system of male piglets and impairs development of the blood–testis barrier

“…The internal structure of the testis is divided into the interstitium and seminiferous tubules [ 14 ]. The interstitium is primarily composed of Leydig cells and macrophages, and it is responsible for testosterone (T) production and secretion [ 15 ]. Spermatogenesis occurs in the seminiferous tubules, which contain Sertoli cells that provide protection and nourishment for spermatogonia and spermatozoa [ 16 ].…”