Trigeminal lesions and maternal behavior in Norway rats: II. Disruption of parturition.

Profound deficits in maternal behavior occur following postpartum bilateral infraorbital denervation (IO-X), with substantial recovery 12-24 h later. In the present experiment, primiparous rats were subjected to IO-X or sham surgery on gestation day 22. Whereas parturition behavior was normal in controls, it was severely disrupted in all IO-X dams. Impairments included absent, abbreviated, or delayed perioral behaviors-nest building, participation in delivery, placentophagia, licking and retrieval of pups-accompanied by increased general activity and delayed onset of nursing. There was increased mortality in the litters of IO-X dams at birth and by postpartum day (PD) 3, and impaired retrieval by IO-X dams on PD1-3. A surgery-birth interval of < 7 h vs. > or = 22 h was associated only with poor litter growth. Thus, prepartum IO-X disrupts onset of maternal behavior during parturition, with long-term consequences for offspring well-being.