Sperm metabolism in pig: a role for peroxisome proliferator-activated receptor (PPAR)γ

Abstract

SUMMARYPeroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear hormone receptor expressed predominantly in adipose tissue, also implicated in energy homeostasis. In this study, we used western blotting and immunofluorescence techniques to demonstrate for the first time that pig spermatozoa express PPARγ. To investigate the functional role of PPARγ in pig sperm, we evaluated its action on different events that characterize the biology of sperm cells, i.e. motility, capacitation, viability and acrosome reaction, using the PPARγ-agonist 15-deoxy-12,14-prostaglandin J2 (PGJ2). In responses to PGJ2 treatment, motility, cholesterol efflux and tyrosine phosphorylation were increased, which broadens the role of PPARγ from that previously described in the literature, as it also acts to improve sperm functionality. To further our understanding of the significance of PPARγ in pig sperm, we focused its effects on lipid and glucose metabolism. Evaluation of triglyceride content and lipase, acyl-CoA dehydrogenase and G6PDH activities suggests that PPARγ induces energy expenditure in pig spermatozoa. These data represent a meaningful advance in the field of sperm energy metabolism. Taken together, our results demonstrate for the first time that PPARγ is expressed by pig sperm, thus improving its functionalities in terms of motility, capacitation, acrosome reaction, survival and metabolism.

Testicular Dysgenesis Syndrome and Long-Lasting Epigenetic Silencing of Mouse Sperm Genes Involved in the Reproductive System after Prenatal Exposure to DEHP

“…PPAR transcripts were significantly higher in high motile semen samples of rams [35]. Pig spermatozoa motility was increased by the PPAR-ɣ ligand PGJ2 and decreased by the specific GW9662 PPAR-ɣ antagonist [36]. Activation of PPAR-ɣ was required for spermatozoa motility in humans [37].…”

Cyclooxygenase and prostaglandins in somatic cell populations of the testis

“…PG receptors have been described in Leydig cells (i.e., EP1, DP, FP, TP, and PPARg receptors; Walch et al 2003, Frungieri et al 2006, Schell et al 2007, Kowalewski et al 2009, Pandey et al 2009), Sertoli cells (e.g., EP1, EP2, EP3, EP4, DP, IP, FP, and PPARg receptors; Ishikawa & Morris 2006, Winnal et al 2007, Kristensen et al 2011, Matzkin et al 2012a, and the seminiferous tubule wall (PPARg receptors; Frungieri et al 2002a). DP prostanoid receptors have also been detected in germ cells of the fetal mouse testis (Moniot et al 2014), whereas functional PPARg and PGE receptors have been found in sperm (Schaefer et al 1998, Santoro et al 2013.…”

Rosiglitazone in the thawing medium improves mitochondrial function in stallion spermatozoa through Akt phosphorylation and reduction of caspase 3

“…The effects of rosiglitazone can be mediated by the PPARγ receptor and or by the phosphorylation of the AMPK. In both cases Akt can be phosphorylated [23]. To test this hypothesis samples were pre-incubated in presence of Akt1/2 inhibitor (30μM), GW9662, inhibitor of PPARγ (10μM) and dorsomorphin, inhibitor of AMPK (100μM) and then incubated in presence of rosiglitazone 75μM.…”

“…The PPAR γ agonist rosiglitazone induced clear improvements in mitochondrial function, and reduced caspase 3 activity, these effects also linked to increased phosphorylation of Akt. Previous reports indicate the importance of Akt phosphorylation in sperm function [15, 16, 52, 53], and recently a link between PPARγ agonists and Akt phosphorylation in human [22] and pig spermatozoa [23] has been reported. Moreover strategies to maintain Akt phosphorylated in spermatozoa have proven to be successful in human sperm cryopreservation [52, 54]…”

“…Thus, the cryopreserved sperm has lower motility and lower ATP content compromising their functionality, and finally their fertilizing ability. Rosiglitazone has proven to enhance the glycolytic capability of stallion spermatozoa maintained in refrigeration for long periods [21], moreover human [22] and porcine [23] studies indicate that rosiglitazone activate pro-survival pathways in spermatozoa. In view of these facts, we hypothesized that thawed stallion spermatozoa may respond to rosiglitazone and thus rosiglitazone supplementation could be a suitable strategy to improve the quality of thawed stallion spermatozoa.…”