Both fertilization promoting peptide and adenosine stimulate capacitation but inhibit spontaneous acrosome loss in ejaculated boar spermatozoa in vitro

Abstract

Both fertilization promoting peptide (FPP) and adenosine stimulate capacitation and inhibit spontaneous acrosome loss in epididymal mouse spermatozoa; these responses involve modulation of the adenylyl cyclase (AC)/cAMP signal transduction pathway. However, it was unclear whether these responses were restricted to the mouse or possibly common to many mammalian species. To address this question, the response of boar spermatozoa to FPP and/or adenosine was evaluated. FPP is found in nanomolar concentrations in seminal plasma of several mammals, but not the pig. When cultured in caffeine‐containing Medium 199 for 2 hr, chlortetracycline fluorescence evaluation indicated that neither FPP nor adenosine stimulated boar sperm capacitation per se but did inhibit spontaneous acrosome loss. However, in caffeine‐free medium, FPP and adenosine both stimulated capacitation and inhibited spontaneous acrosome loss, suggesting that boar spermatozoa have receptors for both FPP and adenosine. Gln‐FPP, a competitive inhibitor of FPP in mouse spermatozoa, has recently been shown to inhibit mouse sperm responses to adenosine as well, suggesting that FPP receptors and adenosine receptors interact in some way. Used with boar spermatozoa, Gln‐FPP also significantly inhibited responses to both FPP and adenosine. These responses suggest that mechanisms whereby FPP and adenosine can regulate sperm function, via AC/cAMP, are of considerable physiological significance. Mouse, human, and now boar spermatozoa have been shown to respond to FPP, suggesting that these mechanisms may be common to many mammalian species. We also suggest that the effects of FPP and adenosine could also be exploited to maximize monospermic fertilization in porcine in vitro fertilization. Mol. Reprod. Dev. 55:117–124, 2000. © 2000 Wiley‐Liss, Inc.

Caffeine promotes premature chromosome condensation formation and in vitro development in porcine reconstructed embryos via a high level of maturation promoting factor activity during nuclear transfer

“…As the control to NT embryos, in vitro maturation, fertilization and culture (IVMFC) of porcine oocytes as described by Miyoshi et al (1999) was performed to produce blastocysts. The IVF medium also contained 2.0 mM caffeine to induce capacitation and spontaneous acrosome reactions of boar spermatozoa (Funahashi et al 2000).…”

Reduction of the incidence of polyspermic penetration into porcine oocytes by pretreatment of fresh spermatozoa with adenosine and a transient co-incubation of the gametes with caffeine

“…It has recently been demonstrated that both adenosine and FPP can regulate the function of freshly ejaculated and frozen-thawed boar spermatozoa (Funahashi et al 2000b). Replacement of caffeine with adenosine or FPP in the fertilization medium in a conventional IVF system improved monospermic penetration by frozen-thawed boar spermatozoa (Funahashi et al 2000c, Funahashi & Nagai 2001.…”

“…These results demonstrated that a combination of preincubation of fresh spermatozoa with adenosine and a transient co-incubation IVF system is effective at narrowing the window of sperm penetration and increasing the incidence of oocytes penetrated by a single spermatozoon. Adenosine stimulates and prevents the capacitation and spontaneous acrosome reaction of boar spermatozoa respectively, via the adenylyl cyclase/cAMP pathway (Funahashi et al 2000b). In the presence of adenosine, the timing of in vitro penetration of frozen-thawed spermatozoa appears to be slower than that in the presence of caffeine (Funahashi & Nagai 2001).…”

“…The methods used for CTC analysis were essentially those described previously (Funahashi et al 2000b) with minor modifications. Briefly, 8 ml of 100 mg Hoechst bis-benzimide 33258/ml (Sigma) was added to 792 ml sperm suspension.…”

Current Concepts of Molecular Events During Bovine and Porcine Spermatozoa Capacitation

“…Allegrucci et al [2001] showed that the A 1 adenosine receptor in human spermatozoa is coupled to Ga i2 and mobilizes calcium stores via IP 3 . It has been proposed that FPP receptors interact with adenosine receptors to help activate the AC=cAMP signaling pathway [Funahashi et al 2000]. Angiotensin II receptors are located on the acrosomal cap region and the flagella of both murine and human spermatozoa resulting in the phosphorylation of both the sperm head and tail via the AC=cAMP=PKA pathway [Mededovic and Fraser 2004].…”