Rationale: Early life stress is a risk factor for the development of psychopathology in later life. Consequences of adverse life events, however, may depend on the genetic makeup of an individual. Reduced serotonin(1A) receptor function may predispose to the development of anxiety disorders.
Objective: Determine susceptibility of serotonin(1A) receptor knockout (1AKO) mice on different background strains to the effects of maternal separation (MS) by assessing startle plasticity in adulthood.
Methods: 1AKO mice on a 129S6 and a Swiss Webster (SW) background were used. MS groups were separated daily from their mother for 180 min/day from postnatal days 2 to 14. Control groups underwent normal animal facility rearing. In adulthood, effects on acoustic startle response, habituation, prepulse inhibition (PPI), and foot shock sensitization were determined.
Results: MS increased startle reactivity and reduced PPI in 129S6 mice. These effects of MS were independent of genotype. MS had no effect on the other readouts. In SW mice, MS had no consistent effect on startle reactivity and did not alter startle plasticity in wild type or in 1AKO mice. 1AKO mice did not differ from wild-type mice in startle plasticity.
Conclusion: Serotonin(1A) receptor deletion does not enhance vulnerability to the effects of MS on startle plasticity. The life-long increase in startle reactivity and PPI deficit induced by MS are strain-dependent. Further, the use of startle reactivity and plasticity may have added value in translational studies relating to early life stress.