Persistent inflammatory pain alters sexually-motivated behavior in male rats

Abstract

Urine from pro-œstrus female rodents evokes increased levels of sexually-motivated behaviors in males, including sniffing and scent marking of the urine spot as well as activation of brain reward regions. Stressors such as social defeat can adversely impact urine scent marking behavior in male rodents, an effect that can be mitigated with anti-depressant drugs. Persistent pain is also known to be a potent stressor, producing elevated levels of plasma corticosterone as well as reduced sucrose preference and reduced social interaction. However, the effect of persistent pain on sexually-motivated behavior is unknown. Here, we compared urine scent marking behavior in male rats for up to 3 weeks following intra-articular injection of Complete Freund’s Adjuvant (CFA) or sham injection. CFA-injected rats exhibited profound and ongoing deficits in static weight bearing capacity. CFA-induced persistent inflammatory pain increased plasma corticosterone levels and reduced urine scent marking behavior in male rats. Moreover, while the vast majority of injured rats showed decreased urine scent marking preference for the pro-œstrus female urine spot, male rats with higher baseline scent marking preference also exhibited higher post-injury scent marking preference, more sniffing behavior and lower levels of plasma corticosterone, compared to those with lower baseline scent marking preference. Overall, scent marking behavior may be an ethologically relevant behavioral predictor of persistent pain-induced stress in rats, representing a novel translational approach to understanding chronic pain comorbidities.

Trigeminal neuropathic pain causes changes in affective processing of pain in rats

“…The full implication of this finding remains to be elucidated, but it is possible to speculate that the chronic pain states cause impairment in social interaction, an idea that is corroborated by previous clinical and non-clinical observations. 18,[36][37][38] It is noteworthy that we failed to detect the emission of aversive (i.e., 22 kHz) USV in the protocol used herein. Previous studies that aimed to analyze 22 kHz USV emission in chronic pain models have similarly failed to see such emissions, suggesting that this call subtype may serve to signal danger, potential danger, or an aversive situation.…”

HomeCageScan analysis reveals ongoing pain in Fabry rats

“…Sniffing behavior in rodents is complex; it can be a way to explore the environment, but it can also accompany different social interactions ( Deschênes et al, 2012 , Pitcher et al, 2019 , Wesson, 2013 ). It is possible that sniffing could be more reflective of exploration of the home cage environment ( Fig.…”

Coordination of social behaviors by the bed nucleus of the stria terminalis

“…In order for these mating interactions to occur appropriately, animals must correctly differentiate between social targets of different sexes as well as display motivation to engage in the sexual encounter. In both humans and rodents, sexual behaviors are profoundly suppressed by both stress and pain (Monga et al, 1998; Hamilton & Meston, 2013; Manzano Nieves et al, 2019; Pitcher et al, 2019). In addition, sexual dysfunction and lack of sexual desire is prevalent among human patients with stress‐related neuropsychiatric disorders like depression and GAD, and the degree of dysfunction is associated with the severity of the disorder (Williams & Reynolds, 2006).…”