Selective serotonin reuptake inhibitors (SSRIs) block the serotonin (5-HT) reuptake transporter (SERT) and increase synaptic 5-HT. 5-HT is also important in brain development; hence when SSRIs are taken during pregnancy there exists the potential for these drugs to affect CNS ontogeny. Prenatal SSRI exposure has been associated with an increased prevalence of autism spectrum disorder (ASD), and peripheral 5-HT is elevated in some ASD patients. Perinatal SSRI exposure in rodents has been associated with increased depression and anxiety-like behavior, decreased sociability, and impaired learning in the offspring, behaviors often seen in ASD. The present study investigated whether perinatal exposure to citalopram causes persistent neurobehavioral effects. Gravid Sprague-Dawley rats were assigned to two groups and subcutaneously injected twice per day with citalopram (10mg/kg; Cit) or saline (Sal) 6h apart on embryonic day (E)6-21, and then drug was given directly to the pups after delivery from postnatal day (P)1-20. Starting on P60, one male/female from each litter was tested in the Cincinnati water maze (CWM) and open-field before and after MK-801. A second pair from each litter was tested in the Morris water maze (MWM) and open-field before and after (+)-amphetamine. A third pair was tested as follows: elevated zero-maze, open-field, marble burying, prepulse inhibition of acoustic startle, social preference, and forced swim. Cit-exposed rats were impaired in the MWM during acquisition and probe, but not during reversal, shift, or cued trials. Cit-exposed rats also showed increased marble burying, decreased time in the center of the open-field, decreased latency to immobility in forced swim, and increased acoustic startle across prepulse intensities with no effects on CWM. The results are consistent with citalopram inducing several ASD-like effects. The findings add to concerns about use of SSRIs during pregnancy. Further research on different classes of antidepressants, dose-effect relationships, timing of exposure periods, and mechanisms for these effects are needed. It is also important to balance the effects described here against the effects of the disorders for which the drugs are given.

Most antidepressants inhibit monoamine reuptake. Selective serotonin (5-HT) reuptake inhibitors (SSRIs) act on the 5-HT transporter (SERT) whereas norepinephrine-dopamine reuptake inhibitors (NDRIs) act on the norepinephrine and dopamine transporters. Epidemiological reports link SSRI use during pregnancy to an increased prevalence of autism spectrum disorder (ASD). We previously showed that perinatal exposure to the SSRI citalopram (CIT) results in rodent offspring that exhibit a number of behaviors consistent with an ASD-like phenotype. The present study examined the effect of perinatal exposure to CIT (at a lower dose), another SSRI, fluoxetine (FLX), and an NDRI, bupropion (BUP). Gravid Sprague-Dawley rats were subcutaneously injected twice per day (6h apart) with 5mg/kg CIT, 5mg/kg FLX, 15mg/kg BUP, or saline (SAL) from embryonic day (E) 6-21, and directly to the pups from postnatal day (P) 1-20. As adults, one male/female from each litter was given one of a series of tests. Both SSRI-exposed groups showed spatial learning deficits in Morris and radial water mazes, increased marble burying, increased acoustic startle, hypoactivity, and attenuated activity to the stimulating effect of the NMDA-R antagonist MK-801. The BUP-exposed group showed a reduction in elevated zero-maze quadrant entries and increased stimulated open-field activity following (+)-amphetamine challenge. These results reinforce concern about the use of antidepressants during pregnancy and highlight how the two classes of drugs produce different constellations of effects with more effects associated with the SSRIs. Further investigation into how antidepressants alter brain development leading to enduring adverse neurobehavioral effects is warranted.

Developmental stress, including low socioeconomic status (SES), can induce dysregulation of the hypothalamic-pituitary-adrenal axis and result in long-term changes in stress reactivity. Children in lower SES households experience more stress and are more likely to be exposed to environmental neurotoxins such as lead (Pb) and manganese (Mn) than children in higher SES households. Co-exposure to stress, Pb, and Mn during early development may increase the risk of central nervous system dysfunction compared with unexposed children. To investigate the potential interaction of these factors, Sprague-Dawley rats were bred, and litters born in-house were culled on postnatal day (P)1 to 6 males and 6 females. One male and female within each litter were assigned to one of the following groups: 0 (vehicle), 10 mg/kg Pb, 100 mg/kg Mn, or 10 mg/kg Pb + 100 mg/kg Mn (PbMn), water gavage, and handled only from P4-28 with half the litters reared in cages with standard bedding (29 litters) and half with no bedding (Barren; 27 litters). Mn and PbMn groups had decreased anxiety, reduced acoustic startle, initial open-field hypoactivity, increased activity following (+)-methamphetamine, deficits in egocentric learning in the Cincinnati water maze (CWM), and deficits in latent inhibition conditioning. Pb increased anxiety and reduced open-field activity. Barren-reared rats had decreased anxiety, CWM deficits, increased startle, and initial open-field hyperactivity. Mn, PbMn, Pb Barren-reared groups had impaired Morris water maze performance. Pb altered neostriatal serotonin and norepinephrine, Mn increased hippocampal serotonin in males, Mn + Barren-rearing increased neostriatal serotonin, and Barren-rearing decreased neostriatal dopamine in males. At the doses used here, most effects were in the Mn and PbMn groups. Few interactions between Mn, Pb, and rearing stress were found, indicating that the interaction of these three variables is not as impactful as hypothesized.