There is strong evidence that neonatal isolation and paternal deprivation affect behaviors and brain functions of adult offspring and these effects are possibly associated with alteration in responses of HPA axis and neuropeptides system at adulthood.However,whether these neonatal manipulations affect offspring behavior and brain functions via alteration of neonatal stress hormone or neuropeptides system,and whether there exists a stress hypo-responsive period (SHRP) in monogamous rodent remains unclear.Using monogamous mandarin vole,it was found that 30 min isolation did not alter the levels of CORT and ACTH at postnatal days 8,10,12 displaying a SHRP,but significantly increased them at postnatal days 4,14,16,18.However,30min isolation significantly increased numbers of AVP-ir neurons in the PVN and SON from postnatal days 4 to 12,it also up-regulated OT-ir neurons in the PVN at postnatal days 4 and 8,and in the SON at postnatal day4.On the other hand,paternal deprived pups showed an increase of ACTH and CORT after 30 min social isolation from postnatal days 8 to 14.They also showed increased AVP-ir neurons in the PVN from postnatal days 10 to 14,but reduced OT-ir neurons in the PVN from postnatal days 10 to 14,and decreased OT-ir neurons in the SON at postnatal days 12 and 14.In summary,the present result indicates that monogamous mandarin voles display a shorter SHRP which can be disrupted by paternal deprivation.The AVP and OT may also be involved in these processes.