Sexual interaction is essential for the transformation of non-copulating rats into sexually active animals by the endocannabinoid anandamide

The endogenous cannabinoid system modulates male sexual behavior expression

The endocannabinoid system (ECS) plays a key neuromodulatory role in the brain. Main features of endocannabinoids (eCBs) are that they are produced on demand, in response to enhanced neuronal activity, act as retrograde messengers, and participate in the induction of brain plasticity processes. Sexual activity is a motivated behavior and therefore, the mesolimbic dopaminergic system (MSL) plays a central role in the control of its appetitive component (drive to engage in copulation). In turn, copulation activates mesolimbic dopamine neurons and repeated copulation produces the continuous activation of the MSL system. Sustained sexual activity leads to the achievement of sexual satiety, which main outcome is the transient transformation of sexually active male rats into sexually inhibited animals. Thus, 24 h after copulation to satiety, the sexually satiated males exhibit a decreased sexual motivation and do not respond to the presence of a sexually receptive female with sexual activity. Interestingly, blockade of cannabinoid receptor 1 (CB1R) during the copulation to satiety process, interferes with both the appearance of the long-lasting sexual inhibition and the decrease in sexual motivation in the sexually satiated males. This effect is reproduced when blocking CB1R at the ventral tegmental area evidencing the involvement of MSL eCBs in the induction of this sexual inhibitory state. Here we review the available evidence regarding the effects of cannabinoids, including exogenously administered eCBs, on male rodent sexual behavior of both sexually competent animals and rat sub populations spontaneously showing copulatory deficits, considered useful to model some human male sexual dysfunctions. We also include the effects of cannabis preparations on human male sexual activity. Finally, we review the role played by the ECS in the control of male sexual behavior expression with the aid of the sexual satiety phenomenon. Sexual satiety appears as a suitable model for the study of the relationship between eCB signaling, MSL synaptic plasticity and the modulation of male sexual motivation under physiological conditions that might be useful for the understanding of MSL functioning, eCB-mediated plasticity and their relationship with motivational processes.

The Biology of BDSM: A Systematic Review

INTRODUCTION

BDSM is an abbreviation used to reference the concepts of bondage and discipline, dominance and submission, sadism and masochism, enacted by power exchanges between consensual partners. In recent years, attention has shifted from the idea of BDSM as a pathological and tabooed niche practice towards viewing BDSM as a healthy form of intimacy.

AIM

This systematic review brings together all existing literature on the biology of BDSM and places it in a broader biological context.

METHODS

A systematic search was conducted on PubMed, Web of Science and PsycARTICLES, of which 10 articles are included and discussed in this systematic review.

RESULTS

There is evidence for cortisol changes in submissives as a result of a BDSM interaction, suggesting involvement of the physiological stress system. Endocannabinoid changes implicate the pleasure and reward system. In dominants, this biologically measured pleasure seemed to be dependent on power play rather than pain play. Testosterone and oxytocin are also implicated in BDSM, though their role is less evident. Research into brain region activity patterns related to BDSM interest suggests a role for the parietal operculum and ventral striatum in the context of the pleasure and reward system, the primary and secondary somatosensory cortex in the context of pain perception, empathy-related circuits such as the anterior insula, anterior midcingulate cortex and sensorimotor cortex and the left frontal cortex in the context of social and sexual interactions. Pain thresholds are shown to be higher in submissive individuals and a BDSM interaction may cause pain thresholds to rise in submissives as well.

CONCLUSION

BDSM interactions are complex and influenced by several psychological, social and biological processes. Though research is limited, there is emerging evidence for an interaction between several biological systems involved in these types of interests and activities. This means there is an important role for future research to replicate and supplement current results.

Exogenous microbiota-derived metabolite trimethylamine N-oxide treatment alters social behaviors: Involvement of hippocampal metabolic adaptation

Increasing evidence indicates that gut microbiota and its metabolites can influence the brain function and the related behaviors. Trimethylamine N-oxide (TMAO), an indirect metabolite of gut microbiota, has been linked to aging, cognitive impairment, and many brain disorders. However, the potential effects of TMAO on social behaviors remain elusive. The present study investigated the effects of early life systemic TMAO exposure and intra-hippocampal TMAO infusion during adulthood on social behaviors in mice. We also analyzed the effects of intra-hippocampus infusion of TMAO during adulthood on levels of metabolites. The results showed that both systemic TMAO exposure in the post-weaning period and intra-hippocampal TMAO infusion during adulthood decreased social rank and reduced sexual preference in adult mice. Data from LC-MS metabolomics analysis showed that intra-hippocampal TMAO infusion induced a total 207 differential metabolites, which belongs to several metabolic or signaling pathways, especially FoxO signaling pathway and retrograde endocannabinoid signaling pathway. These data suggest that TMAO may affect social behaviors by regulating metabolites in the hippocampus, which may provide a new insight into the role of gut microbiota in regulating social behaviors.

Male Ejaculatory Endophenotypes: Revealing Internal Inconsistencies of the Concept in Heterosexual Copulating Rats

Distinct manifestations of sexual behavior are conceived as separate phenotypes. Each sexual phenotype is assumed to be associated with a characteristic brain. These notions have justified the phenotyping of heterosexual copulator males based upon their ejaculation's latencies (EL) or frequencies (i.e., cumulative ejaculation number; EN). For instance, men and male rats showing premature, normal or retarded ejaculation are assumed to be distinctive endophenotypes. This concept, nonetheless, contradicts past and recent evidence that supports that sexual behavior is highly variable within each sex, and that the brain sexual functional morphology represents an intricate sexual phenotypic mosaic. Hence, for ejaculatory male endophenotypes to be considered as a valid biological concept, it must show internal consistency at various levels of organization (including genetic architectures), after being challenged by intrinsic and/or extrinsic factors. We then judged the internal consistency of the presumed ejaculatory endophenotypes by assessing whether copulatory behavior and the expression of copulation relevant genes and brain limbic structures are specific to each of the presumed EL- or EN-ejaculatory endophenotypes. To do this, copulating male rats were first phenotyped in groups consistently displaying short, average or long ejaculation latencies or very high, high, average, low or very low EN, based in their copulatory performance. Then, the internal consistency of the presumed EL- or EN-endophenotypes was tested by introducing as covariates of phenotyping other copulatory parameters (e.g., number of intromissions) in addition to EL or EN, or by analyzing the expression levels of genes encoding for estrogen receptor alpha, progesterone receptor, androgen receptor, aromatase, DNA methyl-transferase 3a and DNA methyl-transferase 1 in the amygdala, medial preoptic area, ventromedial hypothalamus and olfactory bulb. We found that even though there were group-level differences in all the variables that were studied, these differences did not add-up to create the presumed EL- or EN-ejaculatory endophenotypes. In fact, the extensive overlapping of copulatory parameters and expression levels of copulation relevant genes in limbic structures across EL- or EN-phenotyped copulating male rats, is not consistent with the hypothesis that distinct ejaculatory endophenotypes exist and that they are associated with specific brain characteristics.

Between Pleasure and Pain: A Pilot Study on the Biological Mechanisms Associated With BDSM Interactions in Dominants and Submissives

BACKGROUND

BDSM is an abbreviation used to reference the concepts of bondage and discipline, dominance and submission, sadism, and masochism, enacted by power exchanges between consensual partners.

AIM

To shed light upon the rewarding biological mechanisms associated with BDSM interactions.

METHODS

A group of 35 BDSM couples (dominant and submissive counterparts) were recruited and tested during a BDSM interaction, with an additional control group of 27 non-BDSM interested people tested in a normal social interaction.

OUTCOMES

We compared the evolution of the stress and reward hormone levels of cortisol, beta-endorphins, and endocannabinoids (2AG and anandamide) in a group of BDSM practitioners before and after an active BDSM interaction with the levels in control individuals.

RESULTS

We showed that submissives showed increases in cortisol and endocannabinoid levels due to the BDSM interaction, with dominants only showing increased endocannabinoid levels when the BDSM interaction was associated with power play.

CLINICAL IMPLICATIONS

This study effectively provides a link between behavior that many think of as aberrant on one hand, and biological pleasure experience on the other, in the hope that it may relieve some of the stigma these practitioners still endure.

STRENGTHS & LIMITATIONS

It is one of the first and largest studies of its kind, but is still limited in sample size and only represents a specific population of Flemish BDSM practitioners.

CONCLUSION

Even though this is one of the first studies of its kind, we can conclude that there is a clear indication for increased pleasure in submissives when looking at biological effects of a BDSM interaction, which was related to the increases in experienced stress. Wuyts E, De Neef N, Coppens V, et al. Between Pleasure and Pain: A Pilot Study on the Biological Mechanisms Associated With BDSM Interactions in Dominants and Submissives. J Sex Med 2020;17:784-792.

Motivational Drive in Non-copulating and Socially Monogamous Mammals

Motivational drives guide behaviors in animals of different species, including humans. Some of these motivations, like looking for food and water, are crucial for the survival of the individual and hence for the preservation of the species. But there is at least another motivation that is also important for the survival of the species but not for the survival of the individual. Undoubtedly, sexual motivation is important for individuals to find a mate and reproduce, thus ensuring the survival of the species. In species with sexual reproduction, when males find a female in the appropriate hormonal conditions, they will display sexual behavior. However, some healthy males do not mate when they have access to a sexually receptive female, even though they are repeatedly tested. These non-copulating (NC) individuals have been reported in murine, cricetid and ungulates. In humans this sexual orientation is denominated asexuality. Asexual individuals are physically and emotionally healthy men and women without desire for sexual intercourse. Different species have developed a variety of strategies to find a mate and reproduce. Most species of mammals are polygamous; they mate with one or several partners at the same time, as occur in rats, or they can reproduce with different conspecifics throughout their life span. There are also monogamous species that only mate with one partner. One of the most studied socially monogamous species is the Prairie vole. In this species mating or cohabitation for long periods induces the formation of a long-lasting pair bond. Both males and females share the nest, show a preference for their sexual partner, display aggression to other males and females and display parental behavior towards their pups. This broad spectrum of reproductive strategies demonstrates the biological variability of sexual motivation and points out the importance of understanding the neurobiological basis of sexual motivational drives in different species.