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Maternal behavior in rats is a highly motivated and well-organized social behavior.The core neural circuits underlying rat maternal behavior have been well elucidated.Recent work has also identified a role of the mesolimbic dopamine system in this behavior.However,considerably less is known about the role of serotonin（5-HT）,and its interactions with dopamine（DA）in maternal care.The present study examined the behavioral and pharmacological mechanisms of the 5-HT2A,and its interactive effects with D2 on maternal behavior using the home-cage maternal behavior and pup preference paradigms.Results showed that:1)Treatment of TCB-2 severely disrupted various active components of maternal behavior,such as pup retrieval,pup licking,pup nursing,and nest building.This disruptive effect was dose-dependently attenuated by the 5-HT2A antagonist MDL100907,but enhanced by the 5-HT2C antagonist SB242084 and 5-HT2C agonist MK212;2)Acute stimulation of D2 receptors by quinpirole equipotently suppressed the pup exploration time,but increased the object exploration,leading to a significant suppression of pup preference;3)Acute blockade of D2 receptors by haloperidol had no effect on pup preference;4)Both quinpirole and haloperidol similarly disrupted various active maternal responses（e.g.pup retrieval,pup licking）in the home cage,but MDL100907(a 5-HT2A antagonist)did not alter any specific maternal effect of quinpirole or haloperidol.These findings suggest that activation of 5-HT2A receptor has a detrimental effect on rat maternal behaviors and there is little interaction between the 5-HT2A blockade and D2 activation in maternal behavior.These findings,together with evidence from the literature,also demonstrate that TCB-2,quinpirole and haloperidol can cause a similar disruption of maternal behavior through different behavioral mechanisms.TCB-2 and quinpirole may disrupt maternal responses by disrupting the executive function necessary for the normal expression of maternal responses,whereas haloperidol may do so by suppressing the maternal motivation.Future research will determine the specific neural circuitry through which 5-HT2A and D2 receptor agonists produce the inhibitory effects on maternal care,and their psychological mechanisms.