The Regulation Of Dopamine And Its Receptors In The Nucleus Accumbens On The Paternal Behavior Of Mandarin Voles

Paternal behavior is one kind of parental care including retrieving, licking and crouching behavior to pups expressed by father during neonatal period. Fathers play an important role in the survival and development of offspring in many mammalian species as mother. In humans, paternal behaviors have a strong influence on the emotional and social development of children. Fathers, more frequently than mothers, leave the family nucleus, or become abusive, leading to offspring that are more likely to grow under stressful conditions and greater susceptibility to abnormal health and social outcomes. In spite of this, because the occurrence of mammalian paternal care is relatively rare, literature on parental behaviors, human or animal, has primarily focused on the interactions between mothers and offspring, with little research directed at understanding paternal behavior. In most of the mammals (including humans), the basic mechanism understanding of parental behavior is mainly from the maternal behavior, so the basic mechanisms underlying paternal behavior in the mammalian are not well understood, and the neural circuitry controlling paternal behaviors remain unclear. However, the work from human, some studies reveal commonalities in parental behaviors and their underlying neural circuits, these highlight the possibility that paternal behavior has components that are strictly masculine with unique neurobiological mechanisms. Therefore, the neuroendocrine mechanisms of paternal cares need further exploration.Dopamine (DA) receptor activity in the nucleus accumbens is critical for maternal behavior, whereas its inactivity facilitates quiescent nursing in lactating rats. However, its role in paternal behavior has not been explored. Here, to explore further the specific mechanism underlying paternal behavior, using method of microinjection and behavioral analysis to detect behavioral response of father to their own pups in the Mandarin voles(Microtus mandarinus), thus, we investigated the effects of DA1-type and DA2-type receptors on paternal behavior within NA in the mandarin voles. Twelve days after birth of pups, parental behavior of male voles was observed for15min beginning20min after i.c.v injection of either SCH23390, SKF23393, etidopride or quinpirole by different doses, control was microinjected with the physiological saline. The behavioral responses were observed and recorded. These results suggest a role for DA receptors in ongoing paternal behavior, as well as the differences in the dopaminergic regulation of parenting. This study can provide insights into neuroendocrine mechanisms of paternal behavior. The main results include the following points:1. Microinfusion of D1DA receptor antagonist, SCH23390into the NA significantly affected nursing behavior, licking behavior, retrieval behavior, approach behavior, investigation behavior, inactive behavior. High dose of SCH23390induced more nursing behaviors and inactive behaviors showing a striking dosage-dependent impairment in paternal behaviors including licking behavior, retrieval behavior, approach behavior, investigation behavior. SCH23390significantly shorten the latency in nursing behavior, but extending latency in licking, retrieval, approach, sniffing and investigation behavior.2. Microinfusions of a low dose or a high dose of D1-type receptor agonist in the NAcc, SKF23393significantly increased latency in nursing behavior, but reducing latency in licking behavior, retrieval behavior, approach behavior, sniffing behavior and investigation behavior. The treatment significantly decreased duration of nursing behavior and inactive behavior, but increased licking behavior, retrieval behavior, approach behavior, sniff behavior and investigation behavior.3. In addition, microinfusions of D2DA receptor antagonist, etidopride into the NA significantly affected approach behavior, investigation behavior and inactive behavior. Administration of etidopride significantly reduced the latency in nursing behavior, but increased latency in licking behavior, retrieval behavior, approach behavior, sniff behavior and investigation behavior, etidopride significantly increased nursing behavior and inactive behavior, meanwhile decreased licking behavior, retrieval behavior, approach behavior, sniff behavior and investigation behavior.4. Microinfusions of D2DA receptor agonist, quinpirole, significantly affected approach behavior and inactive behavior, quinpirole increased the latency in nursing behavior and inactive behavior, however, but reduced latency in licking behavior, retrieval behavior, approach behavior, sniff behavior and investigation behavior. Quinpirole significantly decreased nursing and inactive behavior, but increased licking behavior, retrieval behavior, approach behavior, sniffing behavior and investigation behavior.5. Exposing paternal dams to pups, induce DA in the nucleus accumbens.According to above results, our results showed that paternal behavior was increased through administration of SKF23393or quinpirole, and quiescently huddled/nursed less than control males. At the high dose of etidopride that inhibition on paternal behavior, but licking, retrieval, approach, investigation behavior was siginificantly inhibited in a dosage-dependent manner by SCH23390within the NA. These datas indicate the importance of DA action on D1receptors in NA for paternal behavior.