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

Immunological castration of male pigs is an attractive alternative to surgical castration used in many countries to reduce the production of the main androgen, androstenone, and skatole, responsible for meat taint. To understand the effect of gonadoliberin (GnRH) vaccination with Improvac on the functional status of Landrace pig testes at the molecular level the role of adipokines was studied. Using western blotting, immunohistochemistry, and enzyme-linked immunosorbent assay, we explored adipokine and leptin signaling and evaluated cholesterol concentrations. In control testis, adiponectin and its receptors were localized to interstitial Leydig cells and spermatogenic cells (especially adiponectin and its receptor 2) while in immunocastrates spermatogenic cells were negative. In control, leptin was exhibited by spermatids and Leydig cells while its receptor only by the later cells. In immunocastrates, leptin immunosignal was not found in spermatogenic cells. In addition, for all studied proteins, the immunosignal was of moderate or weak intensity when compared to the control. Concomitantly, decreased expression of all proteins (p < 0.5) was detected. Similarly, in immunocastrates, cholesterol concentrations were increased (p < 0.01). In summary, we showed for the first time the coincidence of disturbed adiponectin signaling and leptin signaling together with increased cholesterol concentration and attenuated spermatogenesis as a result of halted androstenone production. Altered GnRH signaling affects the adipokine system in testes of Landrace castrates which may impact further functional changes leading to complete spermatogenesis alteration, as well as lipid homeostasis and fattening perturbances.

Automated summary

This study revealed, for the first time, the effects of GnRH vaccination on the testicular function of Landrace pigs. It showed disrupted adiponectin and leptin signaling, increased cholesterol concentration, and attenuated spermatogenesis due to halted androstenone production. The altered GnRH signaling may impact the adipokine system in the testes, leading to further functional changes and lipid metabolism disturbances.