Social amnesia in mice lacking the oxytocin gene

The development of social familiarity in rodents depends predominantly on o lfactory cues and can critically influence reproductive success(1,2). Resea rchers have operationally defined this memory by a reliable decrease in olf actory investigation in repeated or prolonged encounters with a conspecific (3-6). Brain oxytocin (OT) and vasopressin (AVP) seem to modulate a range o f social behaviour from parental care to mate guarding(7). Pharmacological studies indicate that AVP administration may enhance social memory(8-10), w hereas OT administration may either inhibit or facilitate social memory dep ending on dose, route or paradigm(1,11-13). We found that male mice mutant for the oxytocin gene (Oxt(-/-)) failed to develop social memory, whereas w ild-type (Oxt(+/+)) mice showed intact social memory. Measurement of both o lfactory foraging and olfactory habituation tasks indicated that olfactory detection of non-social stimuli is intact in Oxt(-/-) mice. Spatial memory and behavioural inhibition measured in a Morris water-maze, Y-maze. or habi tuation of an acoustic startle also seemed intact. Treatment with OT but no t AVP rescued social memory in Oxt(-/-) mice, and treatment with an OT anta gonist produced a social amnesia-like effect in Oxt(+/+) mice. Our data ind icate that OT is necessary for the normal development of social memory in m ice and support the hypothesis that social memory has a neural basis distin ct from other forms of memory.