Transcriptional abundance of type-1 endocannabinoid receptor (CB1) and fatty acid amide hydrolase (FAAH) in bull spermatozoa: Relationship with field fertility
Introduction
Endocannabinoids, their molecular targets (receptors), their synthetic and degrading enzymes and proteins that transport the ligands in and out of the cells constitute the endocannabinoid system (ECS) [1]. Among the endocannabinoids, N-Arachidonoylethanolamide (Anandamide, AEA) was the first to be discovered and is the most studied [2]. A fully functional ECS that synthesize, bind and degrade AEA is reported in human [3,4], boar [5], mouse [6,7], and bovine [8] spermatozoa. Further, it has been reported that AEA protect spermatozoa during cryopreservation [9], play a role in sperm acquisition of fertilizing potential [10,11] and modulate sperm-oviduct binding and subsequent release [8,12]. The action of AEA is mediated through type-1 (CB1) and type-2 (CB2) endocannabinoid receptors; however CB1 is involved in the sperm acquisition of fertilizing ability and oviduct binding [12,13].
Recent evidences indicate the role of ECS on reproductive potential of men [14]. Studies have shown that the ECS is a key player in the multifaceted process of male reproduction [10,15]. Activation of CB1 modulates motility, capacitation, and acrosome reaction in human, bovine and boar spermatozoa [3,5,8]. On the other hand, membrane-bound fatty acid amide hydrolase (FAAH) controls the cellular uptake of AEA and quickly terminate its effect [16]. The genetic loss of FAAH in the mouse resulted in increased levels of AEA in the reproductive system, leading to an impairment of sperm fertilizing ability [7]. In infertile men, it is reported that alterations in the ECS might impact sperm capacitation and acrosome reaction, and hence fertilization outcomes [10]. Very recently, we have shown that the effect of AEA on sperm-oviduct binding was mediated through CB1 receptor and CB1 antagonist reversed the inhibitory effect of AEA on sperm oviduct binding in buffalo bulls [12]. Accumulating evidences in human being indicate a possible role of ECS in male fertility [3,4,6,10]. Although the effect of exogenous or endogenous cannabinoid signaling on sperm functions has been studied to some extent, little is known about the possible involvement of the ECS in sperm in male fertility in livestock.
Since evidence indicates that AEA signaling might regulate sperm functions and fertility [4,5,10,17], we hypothesised that the expression of CB1 and FAAH might differ in spermatozoa from bulls with different field fertility ratings. Thus, the aims of the present study were 1) to study the transcriptional abundance of CB1 and FAAH in dairy bulls with different field fertility ratings and 2) to investigate their relationship with field fertility of the bulls.
Section snippets
Materials and methods
The present study was undertaken at Theriogenology Laboratory, ICAR-National Dairy Research Institute, Karnal. All the experimental procedures were approved by the Institute Animal Ethics Committee [IAEC/4/36].
Results
The proportion of viable spermatozoa was significantly (p < 0.05) lower in low fertile bulls compared to either high or medium fertile bulls. The proportion of capacitated spermatozoa was significantly (p < 0.05) higher in low fertile bulls compared to both high and medium fertile bulls (Fig. 2). There was no significant difference in the proportion of protamine deficient spermatozoa among the three categories of the bulls.
The results of q-PCR experiments on gene expression of the
Discussion
Our finding indicates that mRNA levels of CB1 receptor was significantly lower in low fertile bulls compared to high fertile bulls, which is in agreement with Lewis et al. [10] who reported that the mRNA levels of both CB1 and CB2 receptors were lower in infertile than fertile sperm in men. Although earlier studies proposed that AEA-signaling regulate sperm functions required for fertilization in humans [22], and human spermatozoa have been shown to express CB1R at the protein and mRNA level [3
Acknowledgements
The authors are thankful to the In-charge and staff of Artificial Breeding Research Centre, Director, ICAR-National Dairy Research Institute, Karnal for providing facilities to conduct the research. We thank the Kerala Livestock Development Board Ltd., Mattupatty and Centre for Advanced Studies in Animal Genetics and Breeding, Kerala Veterinary and Animal Sciences University, Mannuthy, Kerala for providing frozen semen of crossbred bulls.
Conflict of interest
None.
References (29)
- et al.
2-Arachidonoylglycerol and the cannabinoid receptors
Chem Phys Lipids
(2000) - et al.
Endocannabinoid control of sperm motility: the role of epididymus
Gen Comp Endocrinol
(2007) - et al.
Incubation of spermatozoa with Anandamide prior to cryopreservation reduces cryocapacitation and improves post-thaw sperm quality in the water buffalo (Bubalusbubalis)
Anim Reprod Sci
(2018) - et al.
Relationship between seminal plasma levels of anandamide congeners palmitoylethanolamide and oleoylethanolamide and semen quality
Fertil Steril
(2014) - et al.
Anandamide exerts a suppressive effect on sperm binding to oviduct explants through CB1 receptors in the water buffalo (Bubalus bubalis)
Anim Reprod Sci
(2017) - et al.
Endocannabinoids, sperm biology and human fertility
Pharmacol Res
(2009) - et al.
Sperm viability, reactive oxygen species, and DNA fragmentation index combined can discriminate between above- and below-average fertility bulls
J Dairy Sci
(2017) - et al.
The central cannabinoid receptor inactivation suppresses endocrine reproductive functions
Biochem Biophys Res Commun
(2001) - et al.
Cannabinoid receptor agonists are mitochondrial inhibitors: a unified hypothesis of how cannabinoids modulate mitochondrial function and induce cell death
Biochem Biophys Res Commun
(2007) - et al.
Anandamide hydrolase: a guardian angel of human reproduction?
Trends Pharmacol Sci
(2004)
Isolation and structure of a brain constituent that binds to the cannabinoid receptor
Science
Human sperm express cannabinoid receptor Cb1, the activation of which inhibits motility, acrosome reaction, and mitochondrial function
J Clin Endocrinol Metab
Characterization of the endocannabinoid system in human spermatozoa and involvement of transient receptor potential vanilloid 1 receptor in their fertilizing ability
Endocrinology
Human sperm express cannabinoid receptor Cb1, the activation of which inhibits motility, acrosome reaction, and mitochondrial function
J Clin Endocrinol Metab
Cited by (5)
Porcine seminal protein-I and II mRNA expression in boar spermatozoa is significantly correlated with fertility
2019, TheriogenologyCitation Excerpt :The diagnosis and prognosis of male fertility are extremely important for successful AI and profitable farm management in the swine industry. Nowadays, transcriptomic and proteomics biomarkers have been introduced [8–12,31] to overcome the weakness of male fertility detection using conventional semen analyses [1,9,28]. However, the use of a single biomarker is less sensitive than combined markers for the diagnosis of several diseases in humans [16–19,32].
Identification of differentially expressed mRNAs and miRNAs in spermatozoa of bulls of varying fertility
2022, Frontiers in Veterinary ScienceA Study of the Regulatory Mechanism of the CB1/PPARγ2/PLIN1/HSL Pathway for Fat Metabolism in Cattle
2021, Frontiers in GeneticsTranscriptomic Profiling of Buffalo Spermatozoa Reveals Dysregulation of Functionally Relevant mRNAs in Low-Fertile Bulls
2021, Frontiers in Veterinary Science