Asic3−/− Female Mice with Hearing Deficit Affects Social Development of Pups

Citation: Wu W-L, Wang C-H, Huang EY-K, Chen C-C ( 2/2 Asic3 Female Mice with Hearing Deficit Affects Social Development of Pups Wei-Li Wu 0 Chih-Hung Wang 0 Eagle Yi-Kung Huang 0 Chih-Cheng Chen 0 Wim E. Crusio, Centre National de la Recherche Scientifique, France 0 1 Graduate Institute of Life Sciences, National Defense Medical Center , Taipei, Taiwan , Republic of China, 2 Institute of Biomedical Sciences , Academia Sinica, Nankang, Taipei, Taiwan , Republic of China, 3 Department of Otolaryngology-Head and Neck Surgery, Tri-Service General Hospital , Taipei, Taiwan , Republic of China, 4 Department of Pharmacology, National Defense Medical Center , Taipei, Taiwan , Republic of China Background: Infant crying is an important cue for mothers to respond adequately. Inappropriate response to infant crying can hinder social development in infants. In rodents, the pup-mother interaction largely depends on pup's calls. Mouse pups emit high frequency to ultrasonic vocalization (2-90 kHz) to communicate with their dam for maternal care. However, little is known about how the maternal response to infant crying or pup calls affects social development over the long term. Methodology/Principal Findings: Here we used mice lacking acid-sensing ion channel 3 (Asic32/2) to create a hearing deficit to probe the effect of caregiver hearing on maternal care and adolescent social development. Female Asic32/2 mice showed elevated hearing thresholds for low to ultrasonic frequency (4-32 kHz) on auditory brain stem response, which thus hindered their response to their pups' wriggling calls and ultrasonic vocalization, as well as their retrieval of pups. In adolescence, pups reared by Asic32/2 mice showed a social deficit in juvenile social behaviors as compared with those reared by wild-type or heterozygous dams. The social-deficit phenotype in juvenile mice reared by Asic32/2 mice was associated with the reduced serotonin transmission of the brain. However, Asic32/2 pups cross-fostered to wild-type dams showed rescued social deficit. Conclusions/Significance: Inadequate response to pups' calls as a result of ASIC3-dependent hearing loss confers maternal deficits in caregivers and social development deficits in their young. - Funding: This study was supported by a start-up fund from the Institute of Biomedical Sciences, Academia Sinica. W.L.W. wishes to additionally thank the Foundation for the Advancement of Outstanding Scholarship for travelling support. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. . These authors contributed equally to this work. Hearing an infants crying and responding to it is one of the most important ways to establish infant-mother interaction[1,2]. Infants cry to let their mothers or caregivers know their discomfort: hunger, coldness, urination, pain, and desire to be held[2]. Maternal responsiveness to infant crying profoundly affects the infant-mother bonding, although two longitudinal studies concluded opposite effects[3,4]. Nevertheless, social development could be hindered in infants with insecure attachment to their mothers. Children growing up with insecure attachment show reduced interaction with peers and low desire to explore an unfamiliar environment[5]. The mothers auditory functions play an important role in responding to infant crying. Mothers with deficits in auditory functions could ignore infant crying and fail to provide prompt response to their children, which may affect the infant-mother bonding[6]. However, little is known about how the acuity of the mothers hearing affects infant-mother bonding, and no longitudinal study has investigated the effect of the infant-mother attachment on social development in adolescence or adulthood. In rodent studies, mouse pups receiving high levels of maternal care show increased neurotrophin levels in the brain, which promotes sociability in adulthood[7]. However, most research into mice maternal behaviors has focused on the effects of the pups central nervous system and social development and not the caregivers auditory sensation related to pup-mother attachment. In rodents, the pup-mother interaction largely depends on wriggling calls and ultrasonic vocalization (USV) ranging from 220 kHz and 3090 kHz respectively[8]. Mouse pups emit wriggling calls to communicate with their dam, when they struggle in the nest[9]. The mother mouse responds to wriggling calls with three types of maternal behaviors: licking of pups, changes of suckling position, and nest building[10]. In addition, mouse pups emit USV when they are separated from their mother or are under uncomfortable situations[11,12]. These distress calls can elicit the dams approach and retrieval behaviors[13]. However, the molecular and neural basis of hearing sensation in response to wriggling calls and USV is largely unknown. Acid sensing ion channels (ASICs) are voltage-independent sodium channels activated by external acidification[14,15]. ASICs are expressed in the peripheral and central nervous systems, including the auditory system[1618]. In the inner ear, both ASIC2 and ASIC3 are distributed in neurons of cochlear spiral ganglia, which transmit the hearing signaling from hair cells to the brain. Whole-cell patch recording studies showed that spiral ganglion neurons respond to protons and generate inward currents. This proton-induced response could be attenuated by amiloride, a nonspecific blocker for ASICs. The proton-induced response in spiral ganglion neurons is largely reduced in Asic22/2 mice, but ASIC2 seems to play a role in noise susceptibility rather than normal hearing ability[16]. In contrast, in studies of clickevoked auditory brainstem response (ABR), mice lacking Asic3 showed progressive hearing loss with age[17]. However, Asic32/2 mice have never been investigated for hearing conditions at high frequencies or ultrasonic ranges. Since ASIC3 is predominantly expressed in sensory neurons but shows only low expression in the brain, we could use Asic32/2 mice to investigate the effect of hearing deficit on maternal behaviors without eliciting a centralnervous-system effect[19,20]. In this study, we aimed to determine the effect of ASIC3dependent hearing deficit on response to pups calls, and maternal behaviors in mice. In addition, we conducted a longitudinal investigation of the Asic32/2 mouse model to explore how maternal response to pups calls affects the social development of pups in adolescence. Materials and Methods Animals The generation of Asic3 knockout (Asic32/2) mice was as described[21]. To dilute the effect of genetic background, the F2 Asic32/2 mice were backcrossed to CD-1 mice for at least 8 generations to generate outbred Asic3+/2 mice. Mice used in this study were derived from the Asic3+/2 mice intercross or offspring from the next generation of th (...truncated)