Paternal deprivation induces vigilance-avoidant behavior and accompanies sex-specific alterations in stress reactivity and central proinflammatory cytokine response in California mice (Peromyscus californicus)

Abstract

Rationale: Early-life stress (ELS) can increase anxiety, reduce prosocial behaviors, and impair brain regions that facilitate emotional and social development. This knowledge greatly stems from assessing disrupted mother-child relationships, while studies investigating the long-term effects of father-child relationships on behavioral development in children are scarce. However, available evidence suggests that fathers may uniquely influence a child's behavioral development in a sex-specific manner. Rodent models examining mother-offspring interaction demonstrate relationships among ELS, neuroinflammatory mediators, and behavioral development; yet, the role paternal care may play in neuroimmune functioning remains unreported.

Objectives: Using the biparental California mouse (Peromyscus californicus), we examined to what extent paternal deprivation impairs social and anxiety-like behaviors, augments peripheral corticosterone (CORT) response, and alters central proinflammatory cytokine production following an acute stressor in adulthood.

Methods: Biparentally reared and paternally deprived (permanent removal of the sire 24 h post-birth) adult mice were assessed for sociability, preference for social novelty, social vigilance, and social avoidance behaviors, followed by novelty-suppressed feeding (NSF) testing for general anxiety-like behavior. Following an acute stressor, circulating CORT concentrations and region-specific proinflammatory cytokine concentrations were determined via radioimmunoassay and Luminex multianalyte analysis, respectively.

Results: In response to a novel same-sex conspecific, social vigilance behavior was associated with reduced sociability and increased avoidance in paternally deprived mice-an effect not observed in biparentally reared counterparts. Yet, in response to a familiar same-sex conspecific, social vigilance persisted but only in paternally deprived females. The latency to consume during NSF testing was not significantly altered by paternal deprivation. In response to an acute physical stressor, lower circulating CORT concentrations were observed in paternally deprived females. Compared to control-reared males, paternal deprivation increased hypothalamic interleukin-1β, but decreased hippocampal IL-6 protein concentration.

Conclusion: Greater social vigilance behavior was demonstrated in paternally deprived mice while they avoided social interaction with a novel same-sex conspecific; however, in response to a familiar same-sex conspecific, paternal deprivation increased social vigilance behavior but only in females. It is possible that different neurobiological mechanisms underlie these observed behavioral outcomes as sex-specific central proinflammatory cytokine and stress responsivity were observed in paternally deprived offspring.

Keywords: Anxiety; Cytokines; Early-life stress; Paternal deprivation; Social behavior; Social vigilance; Stress reactivity.

Fig. 1

Study design and behavioral testing timeline. a) On postnatal day (PND) 1 (i.e., 24 hours after the birth of offspring), litters were randomly assigned to either the biparental care group (i.e., reared by both the maternal and paternal rodent) or the paternal deprivation group (i.e., reared solely by the maternal parent). All litters were left undisturbed (except for routine husbandry care) until weaning. b) Biparentally-reared and paternally-deprived California mice were weaned between PNDs 30 and 35 and placed in same-sex housing dyads or triads. For Experiment 2, one week after weaning, mice were weighed weekly until the commencement of behavioral testing. Between PNDs 90 and 120, adult offspring underwent behavioral testing for three-chamber social interaction and novelty-suppressed feeding behavior to assess social behaviors and general anxiety-like behavior, respectively. One day after the conclusion of the novelty-suppressed feeding test, mice received an intraperitoneal (IP) saline injection (i.e., an acute physical stressor). The prefrontal cortex, hippocampus, hypothalamus, and blood samples were collected 4-6 hours (h) after the saline injection.

Fig. 2

Regardless of sex and rearing, adult California mice display impaired sociability. a) Using a three-chamber social interaction chamber, mice explored an empty chamber, a center chamber, or a chamber that contained a novel same-sex conspecific (Stranger 1) for 10 minutes. Percent time spent within each chamber was measured. Mice demonstrate sociability by exploring the chamber holding Stranger 1 more than the empty chamber. b) Regardless of rearing, adult female California mice spent more time with Stranger 1 and in the empty chamber than in the center chamber. Bars represent mean ± SEM. *, p≤0.05. ***, p≤0.001. c) Regardless of rearing, adult male California mice spent more time with Stranger 1 and in the empty chamber than in the center chamber. Bars represent mean ± SEM. ****, p≤0.0001.

Fig. 3

Social vigilance reduces sociability and increases avoidance in paternally-deprived adult California mice. a) Regardless of sex and rearing, the duration of social vigilance during the sociability test was not affected. b, right) In biparental females, no significant correlations were observed between social vigilance and time spent with Stranger 1 and time spent in the empty chamber. b, left) In paternally-deprived females, significant correlations were observed between social vigilance and time spent with Stranger 1 and time spent in the empty chamber during the sociability test. c, right) In biparental males, no significant correlations were observed between social vigilance and time spent with Stranger 1 and time spent in the empty chamber. c, left) In paternally-deprived males, significant correlations were observed between social vigilance and time spent with Stranger 1 and time spent in the empty chamber during the sociability test.

Fig. 4

Paternal deprivation does not alter preference for social novelty. a) Immediately after sociability testing, preference for social novelty was assessed within a three-chamber social interaction chamber for 10 minutes. Mice explored an empty chamber, or a chamber housing Stranger 1 (a now-familiar rodent) and a novel same-sex conspecific (Stranger 2). Percent time spent within each chamber was measured. Mice exhibiting a preference for social novelty should spend more time exploring the chamber holding Stranger 2 than Stranger 1. b) Percent time spent exploring each chamber did not differ because of rearing experience in female mice. c) Regardless of rearing, males spent more time exploring the novel mouse (Stranger 2) than the center chamber. Bars represent mean ± SEM. **, p≤0.01.

Fig. 5

Adult California mice exhibit innate social avoidance, irrespective of sex and rearing experience. a) Twenty-four hours following preference for social novelty testing within the three-chamber social interaction chamber, mice explored an empty chamber, a center chamber, or a chamber that contained a familiar same-sex conspecific (Familiar rodent; Stranger 1 from Day 1 of testing) for 10 minutes. Percent time spent within each chamber was measured. Mice demonstrate social anxiety by exploring the empty chamber more than chamber holding the Familiar rodent. b) Female mice spent more percent time exploring the empty chamber than the center chamber and the chamber holding the familiar rodent. Bars represent mean ± SEM. ****, p≤0.0001. c) Regardless of rearing, males spent more percent time in the empty chamber than with the Familiar rodent and the center chamber. Also, males spent more percent time with the Familiar rodent than in the center chamber. Bars represent mean ± SEM. *, p≤0.05. **, p≤0.01. ****, p≤0.0001.

Fig. 6

Regardless of sex and rearing, social vigilance is not associated with innate social anxiety-like behavior in California mice. a) Regardless of sex and rearing, the duration of social vigilance during the social anxiety test was not affected. b, right) In biparental females, no significant correlations were observed between social vigilance and percent time spent with the Familiar rodent and percent time spent in the empty chamber. b, left) In paternally-deprived females, no significant correlations were observed between social vigilance and percent time spent with the Familiar rodent and percent time spent in the empty chamber. c, right) No significant correlations were observed between social vigilance and percent time spent with the Familiar rodent and percent time spent in the empty chamber in biparentally-reared males. c, left) No significant correlations were observed between social vigilance and percent time spent with the Familiar rodent and percent time spent in the empty chamber in paternally-deprived males.

Fig. 7

Paternal deprivation increases general anxiety-like behavior. a) Forty-eight hours after assessing social anxiety-like behavior, mice were food-deprived (24 hours) and tested for novelty-suppressed feeding behavior. The latency to consume a food pellet in the center of a brightly lit was recorded, with a longer latency characterized as general anxiety-like behavior. b) Mice exposed to paternal deprivation exhibited a longer latency to consume than biparentally-reared mice. *, p≤0.05. Bars represent the median ± 95% confidence interval.

Fig. 8

Sex-dependent modulations in circulating corticosterone and proinflammatory cytokine concentration following paternal deprivation. a) Regardless of rearing, females had a higher concentration of IL-1β in the hypothalamus than in the frontal cortex. Bars represent mean ± SEM. **, p≤0.01. b) Hypothalamic IL-1β concentration was significantly higher in paternally-deprived male mice than in biparentally-reared males. Bars represent mean ± SEM. *, p≤0.05. c) In females, there was a significant effect of brain region on IL-6 concentrations. Regardless of rearing, females had a higher concentration of IL-6 in the hypothalamus than in the frontal cortex. Bars represent mean ± SEM. *, p≤0.05. d) In males, there were no significant differences between biparentally-reared and paternally-deprived mice across brain region-specific comparisons of IL-6. e) In females, regardless of rearing, there were higher concentrations in the frontal cortex. Bars represent mean ± SEM. ***, p≤0.001. f) Regardless of rearing, males had higher concentrations of TNF-α in the hypothalamus than in the frontal cortex and hippocampus. Bars represent mean ± SEM. ***, p≤0.001. ****, p≤0.0001.