Sex-specific modulation of juvenile social play by vasopressin

“Coordinates in mm from bregma were: lateral ventricle (+1.0 AP, 1.6 LM; 1.6 DV); LS (+0.4 AP, 1.0 LM, 3.6 DV; Paxinos & Watson, 2007).”

“In adult humans they have been found to modulate social trust, social cooperation, and social cognition in adult humans (Kosfeld et al., 2005; Guastella et al., 2010; Rilling et al., 2012).”

“The neuropeptides vasopressin (AVP) and oxytocin (OXT) have been found to modulate various social behaviors such as pair bonding, aggression, and social recognition in adult rodents (Donaldson & Young, 2008; Veenema & Neumann, 2008; Goodson & Thompson, 2010).”

“For example, ASD typically appear early in development and are four to eight times more common in males than in females (Fombonne, 2003; Beaudet, 2012).”

“Social play is thought to contribute to the development of social and emotional skills in humans and animals (Baldwin, 1986; Pellegrini, 1988; Vanderschuren et al., 1997; Bekoff & Byers, 1998; Van den Berg et al., 1999; Guralnick et al., 2006; Cordoni & Palagi, 2011).”

“However, these sex differences in social play disappear when rats are briefly isolated and tested for social play in resident-intruder settings (Panksepp & Beatty, 1980; Panksepp, 1981; Thor & Holloway, 1984).”

“Moreover, reduced anxiety is found in AVP V1a receptor (V1aR) knockout male, but not female, mice (Bielsky et al., 2004, 2005).”

“Sex differences in behavioral or brain responses were also found after manipulations of the OXT brain system in voles (Insel & Hulihan, 1995) and after intranasal OXT application in humans (Kubzansky et al., 2012; Lischke et al., 2012).”

“To test whether AVP projections of the BNST or MeA modulate social play, we targeted the LS because this area receives projections from AVP-expressing neurons in the BNST and MeA that are denser in males than in females (De Vries & Buijs, 1983; Van Leeuwen et al., 1985; Caffe et al., 1987).”

“These findings suggest that AVP and OXT modulate social behaviors in sexually dimorphic ways, but do not necessarily suggest that these neuropeptides cause sex differences in behavior (De Vries, 2004).”

“Social play (also referred to as play-fighting or rough-andtumble play) is predominantly displayed by juvenile animals, including human children (Panksepp, 1981; Bekoff & Byers, 1998; Pellis & Iwaniuk, 2000; Burghardt, 2005).”

“Conversely, social play deficits are observed in neurodevelopmental disorders such as autism spectrum disorders (ASD), early-onset schizophrenia, and attention-deficit/hyperactivity disorder (Alessandri, 1992; Moller & Husby, 2000; Jordan, 2003).”

“In humans, AVP has sex-specific effects on social communication (Thompson et al., 2006) and V1aR polymorphisms correlate with pair-bonding behavior in men, but not in women (Walum et al., 2008).”

“Instead, the widespread distribution of V1aR throughout the brain, including many areas that border the ventricles (Tribollet et al., 1988), suggests that the effects of ICV injections on social play reflect a net inhibition of V1aR activation in multiple brain regions.”

“However, these sex differences in social play disappear when rats are briefly isolated and tested for social play in resident-intruder settings (Panksepp & Beatty, 1980; Panksepp, 1981; Thor & Holloway, 1984).”

“Previous studies have shown that social play in juvenile rats is modulated by a wide variety of neuroactive agents, including opioids, dopamine, cannabinoids, norepinephrine, serotonin, and GABA (Vanderschuren et al., 1997; Siviy, 1998; Trezza et al., 2010).”

“This sex difference, already present in juveniles (De Vries et al., 1981), is found in many mammalian species (De Vries & Panzica, 2006).”

“The neuropeptides vasopressin (AVP) and oxytocin (OXT) have been found to modulate various social behaviors such as pair bonding, aggression, and social recognition in adult rodents (Donaldson & Young, 2008; Veenema & Neumann, 2008; Goodson & Thompson, 2010).”

“In humans, AVP has sex-specific effects on social communication (Thompson et al., 2006) and V1aR polymorphisms correlate with pair-bonding behavior in men, but not in women (Walum et al., 2008).”

“…lateral ventricle of Ringer’s solution (vehicle) (pH 7.4; 5 ml Ringer; males n = 8; females n = 10), the specific V1aR antagonist d(CH2)5Tyr(Me2)AVP (Manning et al., 2008; 0.75 mg/5 ml Ringer; males n = 11; females n = 8), or the specific OTR antagonist des-GlyNH2,d(CH2)5[Tyr(Me) 2,Thr4]OVT…”

“To test whether AVP projections of the BNST or MeA modulate social play, we targeted the LS because this area receives projections from AVP-expressing neurons in the BNST and MeA that are denser in males than in females (De Vries & Buijs, 1983; Van Leeuwen et al., 1985; Caffe et al., 1987).”

“, 1993), but injections into the lateral septum did (Liu et al., 2001).”

“The neuropeptides vasopressin (AVP) and oxytocin (OXT) have been found to modulate various social behaviors such as pair bonding, aggression, and social recognition in adult rodents (Donaldson & Young, 2008; Veenema & Neumann, 2008; Goodson & Thompson, 2010).”

“Social play was assessed in 35-day-old juvenile rats because social play is highest at this age (Panksepp, 1981; Pellis & Pellis, 1990), following a procedure described in Veenema & Neumann (2009).”

“Social play (also referred to as play-fighting or rough-andtumble play) is predominantly displayed by juvenile animals, including human children (Panksepp, 1981; Bekoff & Byers, 1998; Pellis & Iwaniuk, 2000; Burghardt, 2005).”

“Social play is thought to contribute to the development of social and emotional skills in humans and animals (Baldwin, 1986; Pellegrini, 1988; Vanderschuren et al., 1997; Bekoff & Byers, 1998; Van den Berg et al., 1999; Guralnick et al., 2006; Cordoni & Palagi, 2011).”

“Conversely, social play deficits are observed in neurodevelopmental disorders such as autism spectrum disorders (ASD), early-onset schizophrenia, and attention-deficit/hyperactivity disorder (Alessandri, 1992; Moller & Husby, 2000; Jordan, 2003).”

“…lateral ventricle of Ringer’s solution (vehicle) (pH 7.4; 5 ml Ringer; males n = 8; females n = 10), the specific V1aR antagonist d(CH2)5Tyr(Me2)AVP (Manning et al., 2008; 0.75 mg/5 ml Ringer; males n = 11; females n = 8), or the specific OTR antagonist des-GlyNH2,d(CH2)5[Tyr(Me) 2,Thr4]OVT…”

“Social play is thought to contribute to the development of social and emotional skills in humans and animals (Baldwin, 1986; Pellegrini, 1988; Vanderschuren et al., 1997; Bekoff & Byers, 1998; Van den Berg et al., 1999; Guralnick et al., 2006; Cordoni & Palagi, 2011).”

“Sex differences in behavioral or brain responses were also found after manipulations of the OXT brain system in voles (Insel & Hulihan, 1995) and after intranasal OXT application in humans (Kubzansky et al., 2012; Lischke et al., 2012).”

“Males show more social play than females when social play is recorded among cage-mates and under undisturbed conditions (Poole & Fish, 1976; Meaney & Stewart, 1981; Parent & Meaney, 2008).”

“Social play was assessed in 35-day-old juvenile rats because social play is highest at this age (Panksepp, 1981; Pellis & Pellis, 1990), following a procedure described in Veenema & Neumann (2009).”

“Importantly, we do not find effects of surgery and cannula or probe implantation after two days on behavior in various behavioral tests (Beiderbeck et al., 2007; Veenema et al., 2010, 2012; Lukas et al., 2011, 2013).”

“Males show more social play than females when social play is recorded among cage-mates and under undisturbed conditions (Poole & Fish, 1976; Meaney & Stewart, 1981; Parent & Meaney, 2008).”

“Importantly, the AVP and OXT systems are sexually dimorphic (De Vries, 2008).”

“Conversely, social play deficits are observed in neurodevelopmental disorders such as autism spectrum disorders (ASD), early-onset schizophrenia, and attention-deficit/hyperactivity disorder (Alessandri, 1992; Moller & Husby, 2000; Jordan, 2003).”

“Males show more social play than females when social play is recorded among cage-mates and under undisturbed conditions (Poole & Fish, 1976; Meaney & Stewart, 1981; Parent & Meaney, 2008).”

“Importantly, we do not find effects of surgery and cannula or probe implantation after two days on behavior in various behavioral tests (Beiderbeck et al., 2007; Veenema et al., 2010, 2012; Lukas et al., 2011, 2013).”

“Sex differences in behavioral or brain responses were also found after manipulations of the OXT brain system in voles (Insel & Hulihan, 1995) and after intranasal OXT application in humans (Kubzansky et al., 2012; Lischke et al., 2012).”

“In adult humans they have been found to modulate social trust, social cooperation, and social cognition in adult humans (Kosfeld et al., 2005; Guastella et al., 2010; Rilling et al., 2012).”

“Time of administration and concentrations of drugs were based on previous studies showing behavioral effects in rats (Lukas et al., 2011, 2013; Veenema et al., 2012).”

“…of OXT in the hypothalamus is significantly higher in female than in male mice (Haussler et al., 1990) while OXT receptor (OTR) binding densities in several brain regions are higher in male than in female rats (Uhl-Bronner et al., 2005; K.M. Dumais and A.H. Veenema, unpublished observations).”

“Importantly, we do not find effects of surgery and cannula or probe implantation after two days on behavior in various behavioral tests (Beiderbeck et al., 2007; Veenema et al., 2010, 2012; Lukas et al., 2011, 2013).”

“Likewise, silencing MeCP2 expression in the MeA reduced social play (Kurian et al., 2008) as well as AVP mRNA expression in the MeA (Forbes-Lorman et al.”

“For example, AVP facilitates partner preference in male, but not female, prairie voles (Cushing et al., 2001).”

“In fact, play-soliciting behaviors were found to be higher in females than in males when playing with an unfamiliar partner (Cirulli et al., 1996).”

“Moreover, reduced anxiety is found in AVP V1a receptor (V1aR) knockout male, but not female, mice (Bielsky et al., 2004, 2005).”

“Social play is thought to contribute to the development of social and emotional skills in humans and animals (Baldwin, 1986; Pellegrini, 1988; Vanderschuren et al., 1997; Bekoff & Byers, 1998; Van den Berg et al., 1999; Guralnick et al., 2006; Cordoni & Palagi, 2011).”

“For example, a prenatal immune challenge reduced social play as well as AVP mRNA expression in the BNST and MeA, but did so in males only (Taylor et al., 2012).”

“Social play is thought to contribute to the development of social and emotional skills in humans and animals (Baldwin, 1986; Pellegrini, 1988; Vanderschuren et al., 1997; Bekoff & Byers, 1998; Van den Berg et al., 1999; Guralnick et al., 2006; Cordoni & Palagi, 2011).”

“Previous studies have shown that social play in juvenile rats is modulated by a wide variety of neuroactive agents, including opioids, dopamine, cannabinoids, norepinephrine, serotonin, and GABA (Vanderschuren et al., 1997; Siviy, 1998; Trezza et al., 2010).”

“AVP cells in the BNST and MeA are more numerous and have denser projections in male than in female juvenile rats (De Vries et al., 1981; Szot & Dorsa, 1993).”

“In juvenile male hamsters, for example, AVP cells in the nucleus circularis and the SON showed enhanced c-Fos immunolabeling after social play, suggesting increased activity (Cheng et al., 2008).”

“However, these sex differences in social play disappear when rats are briefly isolated and tested for social play in resident-intruder settings (Panksepp & Beatty, 1980; Panksepp, 1981; Thor & Holloway, 1984).”

“, 2008) as well as AVP mRNA expression in the MeA (Forbes-Lorman et al., 2012) in males but not in females.”

“Furthermore, V1aR blockade in the anterior hypothalamus (which is a possible projection site of AVP cells in the nucleus circularis and SON; Cheng et al., 2008) decreased the number of attacks and bites during social play in juvenile male hamsters (Cheng & Delville, 2009).”

“For example, ASD typically appear early in development and are four to eight times more common in males than in females (Fombonne, 2003; Beaudet, 2012).”

“For example, VP system manipulations in the LS produced opposite effects on social play behavior in juvenile rats (Veenema et al., 2013; Bredewold et al., 2014), intranasal VP produced opposite effects on facial perception in humans (Thompson et al.”

“…seems to be very complex as in many behavioral and cognitive aspects both peptides modulatory interact (Neumann, 2009; Bosch and Neumann, 2012; Stoop, 2012) and furthermore, as constituting a sexual dimorphic systems, vary in their relative priority in males or females (Veenema et al., 2013).”

“, intracerebroventricular injections (ICV)) on play behavior in rats (Veenema et al., 2013).”

“…and because the injection site corresponds with previous studies showing that pharmacological manipulations of AVP and OXT systems in the rat lateral septum altered social behavior (Veenema et al., 2010, 2012, 2013; Lukas et al., 2013), indicating that the drugs are reaching their target receptors.”

“2016), as well as in juveniles (Veenema et al. 2013; Bredewold et al. 2014), we hypothesize that sex differences in OTR and V1aR binding previously observed in adults (Dumais et al.”

“Sexual dimorphism in LS-AVP signaling is demonstrated by the fact that inhibition of V1aR lowers home cage social play behavior in female rats but enhances home cage social play behavior in males [36].”

“Finally, the abovediscussed studies have shown that the sex-specific regulation of social and anxiety-related behaviors by the AVP system is evident during early development [27 ,28].”

“A role for vasopressin in play is supported by a finding that intracerebroventricular infusions of a vasopressin antagonist reduces play in male rats (Veenema et al., 2013) although this same study reported an increase in male rats and a decrease in female rats when the same antagonist was infused into the lateral sep…”

“Similar to OT, AVP can also have sexually differentiated effects in both humans and non-human animals (Thompson et al. 2006; Veenema et al. 2013), so it is important to examine AVP effects in both men and women.”

“Moreover, AVP signaling in the LS regulates social play behavior in juvenile rats (Bredewold et al., 2014; Veenema et al., 2013).”

“In rats, a V1a antagonist reduces social play in males while increasing them in females when injected intracerebroventricularly, but has the exact opposite effect when injected into the septum (Veenema et al., 2013).”

“, 2014), sexually dimorphic social play (Veenema et al., 2013), social preference (Shin et al.”

“Specifically, pharmacological blockade of V1aR in the LS increased social play behavior in juvenile male rats but reduced social play behavior in females (94, 95), and a similar effect was found in the ventral pallidum (96).”

“Moreover, the effects of some manipulations don’t just differ by sex, but may push the brain and behavior in opposite directions in males and females (e.g., Oomen et al., 2009; Shors et al., 2001; Veenema et al., 2013; Waddell et al., 2008).”

“an increase in males and a decrease in females (Bredewold et al., 2018; Veenema et al., 2013).”

“Veenema et al. ( 44 ) demonstrated that blockade of LS V1aR enhanced same-sex social play in males, suggesting that VP-V1aR binding may have antisocial functions in males.”

“In rats, for example, treatment with a V1aR antagonist in the lateral septum significantly increased social play in males while decreasing social play in females (54).”

“Another factor to be pointed out is that both strain and sex differences have been reported in both social play behaviour (e.g. Bredewold et al., 2014; Veenema et al., 2013), the behavioural effects of opioid drugs (Manduca et al.”

“…in our and other laboratories have demonstrated that AVP 1a receptor (V1aR) antagonists influence levels of play fighting in juvenile hamsters and rats (Cheng and Delville, 2009; Veenema et al., 2013), but the direction of these effects depends upon the sex of the subject and brain area injected.”

“The importance of central AVP acting on V1aR in the modulation of rodent social behavior has been well-established (Lukas and Neumann 2013) and is often sexually-differentiated (Veenema et al. 2013; Dumais and Veenema 2016; Duque-Wilckens et al. 2016; Rigney et al. 2019).”

“V1aR in selected brain areas is also implicated in a variety of social behaviors including social affiliation and recognition [40,41], parental behavior [63,76], and pair bonding [37,77].”

“Therefore, it increases social play in male, but decreases it in female rats [130].”

“For example, injections of AVP antagonists (Bluthe et al., 1993, 1990; Caldwell et al., 2008; Veenema et al., 2012, 2013) or V1aR gene manipulations (Bielsky et al., 2005, 2004) affect social behavior, often in a sex-dependent manner.”

“In the LS, the vasopressin receptor 1a is important for social play in juvenile rats (Veenema et al., 2013) and social recognition memory (Ferguson et al.”

“We have previously shown that this short recovery period does not affect the expression of social novelty preference or other social behaviors, such as social play in juvenile rats (Veenema et al., 2012, 2013; Bredewold et al., 2014, 2015; Smith et al., 2015, 2017b).”

“The literature has strongly suggested the existence of sexual dimorphism in the behavioral effects of OXT and AVP (Carter, 2007; De Vries, 2008; Veenema et al., 2013; Wang et al., 2000).”

“, 2014), and social play behavior (Veenema et al., 2013) has been proposed by a mechanism involving vasopressin.”

“One region of particular interest is the lateral septum, because it shows the most robust age difference in MOR binding density, is reciprocally connected to the mesolimbic reward system (Swanson 1982), and it is involved in social play (Veenema et al. 2013; Bredewold et al. 2014, 2015), a highly rewarding and juvenil…”

“There is also some experimental evidence that social neuropeptides, vasopressin and oxytocin, playing a substantial role in regulation of social behavior during adulthood (Veenema and Neumann, 2008), are sex-dependently involved in modulation of play fighting (Bredewold et al., 2014; Veenema et al., 2013).”

“In addition, V1aR blockade in the LS increased social play behavior in males and decreased it in females, but only when it tested in a familiar environment (Bredewold et al., 2014; Veenema et al., 2013).”

“Vasopressin expressed in the brain modulates social behaviours in sexually dimorphic ways, including anxietyrelated behaviour as shown in animal studies, and may act to enhance social recognition and the emotional response to stress [3–5].”

“Importantly, there is evidence that the neurophysiology underlying play behavior is differentially regulated in males and females: the V1ar vasopressin receptor promotes play behavior inmales, but inhibits play behavior in females [71].”

“The frequency of main stereotypical play behaviors, specifically, nape attacks (resident attacks or makes nose contact with nape of intruder), pins (resident holds intruder in supine position) and supine positions (resident is pinned on its back by intruder) was also analyzed (individually as well as total), according…”

“This pathway regulates a variety of social and anxiety-like behaviours (Beiderbeck et al., 2007; Bredewold et al., 2014; Caldwell & Albers, 2016; Landgraf et al., 1995; Liebsch et al., 1996; Veenema et al., 2012, 2013).”

“For example, hypothalamus (Hypo), bed nucleus of stria terminalis (BNST) and lateral septum (LS) differentially modulate social play in adolescent males and females (Paul et al., 2014; Veenema et al., 2013).”

“Furthermore, acute blockade of V1a receptors via ICV infusions of an AVP antagonist has opposite actions on play behavior of male and female rats (Bredewold et al., 2014; Veenema et al., 2013).”

“AVP signaling in the brain has been shown to be necessary for the display of many species-typical social behaviors including social recognition, aggression, social play, pair bonding and parental care (Winslow et al., 1993; Bamshad et al., 1994; Ferris et al., 1997; Albers et al., 2006; Veenema et al., 2010; Veenema e…”

“In contrast, pretreatment with an OXT antagonist did not influence the frequency of play in either of the sexes (Veenema et al., 2013).”

“Our finding of no sex difference in rough-and-tumble play aligns with previous reports, which also used pretest social isolation to motivate the subjects to play (Veenema et al., 2013; Bredewold et al., 2014, 2015; Reppucci et al., 2018; Kisko et al., 2020).”

“The same manipulations also influence juvenile rat play behavior (Veenema et al., 2013) and pair bond formation in prairie voles (Liu et al.”

“Alternatively, vasopressin and oxytocin have been shown to regulate social play behavior in a sex-specific way at the juvenile age [36,37].”

“Interestingly, in rats, the vasopressin system regulates the development of social play in a sex-specific manner (Paul et al., 2014; Veenema et al., 2013).”

“[62] Wistar PN35 2 days Unfamiliar Home No sex differences”

“In addition, V1aR blockade in the LS increased social play behavior in males and decreased it in females, but only when it tested in a familiar environment (136, 137).”

“For example, intracerebroventricular (ICV) administration of AVPR1a antagonists in rats increased social play in females and decreased it in males (49).”

“Alternatively, the protocol can be performed as a single-trial to study sex differences in the activation of neural circuitry underlying play (Veenema et al., 2013; Bredewold et al., 2018).”

“Indeed, studies have shown that the LS regulates prosocial behavior 72–75 as well as aggression 32,40,76,77 .”

“We previously showed that AVP, glutamate, and GABA systems in the LS modulate social play behavior in male and female juvenile rats [27 – 29].”

“site effects on social play expression (Veenema et al., 2013).”

“Such overlap notably affects a greater range of socially motivated behaviors as, for instance, variations in V1aR expression in the LS are linked to social approach in prairie voles [61], whereas V1aR blockade in the LS increases social play in juvenile male rats [62].”

“highlighted an important role for the nonapeptide vasopressin, where administration of vasopressin receptor antagonists reduces play behavior in male rats (Cheng and Delville, 2009; Veenema et al., 2013).”