Differential effects of communal rearing and preweaning handling on open-field behavior and hot-plate latencies in mice.
On day 2 after delivery, dams of the DBA/1 mouse inbred strain (n = 20/group) with their litter were allocated to one of the following groups: NH21, nonhandling, housed 1 litter/cage, weaned on postnatal day (PND) 21;H21, handling, housed 1 litter/cage, weaned on PND 21; NH30, nonhandling, group-housed (5 litters/cage), weaned on PND 30; H30, handling, group-housed (5 litters/cage), weaned on PND 30. Two male pups of each litter were color marked on PND 2. From PND 8-21 they were removed from their cage, gently held in the experimenter's hand for 5 min/day. The two marked males of each litter were housed together after weaning, and tested in the open-field on PNDs 51-53, and one of each of these siblings was tested for hot-plate latencies on PND 54. Being raised in group-housing and weaned on PND 30 resulted in offspring exhibiting shorter latencies to initiate behavior and higher percentages of centerfield entries in the open field, hot-plate latencies, however, remained unaffected. Preweaning handling increased hot-plate latencies and the number of grooming episodes in the open field, and it decreased defecation, percent centerfield entries and open-field activity in general. It is concluded that the two forms of early experience have different effects on neurobehavioral endpoints 8 weeks after birth.
Clausing
P
P
Division of Neurotoxicology, National Center for Toxicological Research, Jefferson, AR 72079-9502, USA. pclausing@nctr.fda.gov
Mothes
H K
HK
Opitz
B
B
Kormann
S
S
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D001923:Brain Chemistry / Q000502:physiology; D003672:Defecation; D005260:Female; D006120:Grooming; D006234:Handling, Psychological; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D010147:Pain Measurement; D011930:Reaction Time / Q000502:physiology*; D012931:Social Environment