Post-natal knockdown of 5-HT1A autoreceptors. (a) Doxycycline was removed from the chow from P0 to P21, resulting in a ∼40% reduction in 5-HT1A autoreceptor levels at P21 in animals carrying the tTs transgene (KD mice). (b–d) Receptor levels were the same in control and KD animals at P14 (n=2/grp), reach maximal knockdown at P21 (n=4–8/grp), and were rescued by P30 (n=3/grp). **p<0.001. (e and f) Consistent with previous reports, hippocampal 5-HT1A receptors are unaffected in control and knockdown animals at either P21, when raphe 5-HT1A receptor knockdown is maximal, or in adulthood (n=4–8/grp).