Peripartum fluoxetine exposure to C57BL/6 dams increased mammary gland Casr, Pthrp, and serotonin synthesis during lactation. Saline (n = 8) or 20 mg/kg fluoxetine (n = 8) was administered from E13 through day 10 of lactation, at which time mice were euthanized. RNA and protein were extracted from the mammary gland and duodenum for quantitative RT-PCR in mRNA and Western blot and assays in protein. (A) Mammary gland mRNA expression of Casr. (B) Western blot and quantification of CaSR. (C) Genomic DNA was extracted, and DNA methylation was measured using methylated DNA immunoprecipitation at the Pthrp promoter. (D) Mammary gland mRNA expression of Pthrp. (E) Mammary gland protein was assayed for cAMP activity. (F) Mammary gland mRNA expression of tryptophan hydroxylase 1 (Tph1). (G) Mammary gland protein was assayed for content of serotonin, expressed as micrograms of serotonin per microgram of protein. (H) Duodenal mRNA expression of Tph1. (I) Duodenal protein was assayed for serotonin content, expressed as micrograms of serotonin per microgram of protein. Data presented as mean ± SEM and analyzed using a Student t test.