Supplementary Information 1: Detailed Methodological Descriptions

Decreased hippocampal volume and increased anxiety in a transgenic mouse model expressing the human CYP2C19 gene

Supplementary Information 1: Detailed methodological descriptions

Supplementary Figure 1: Distribution of CYP2C19 mRNA expression in the brain

Supplementary Figure 2: Size measurements in brain sections from CYP2C19Tg-Hom and Wt mice at PND0

Supplementary Figure 3:Brain weights

Supplementary Figure 4: BrdU and Ki-67 positive cells in the hippocampus

Supplementary Figure 5: Number of BrdU, Ki-67, DCX, and PA positive cells in the hippocampus corrected by hippocampal size

Supplementary Figure 6:Immobility time in the Morris Water Maze

Supplementary Figure 7:Plasma corticosterone levels before and after acute restraint stress

Supplementary Information 1: Detailed methodological descriptions

Transgenic mice

Mice (C57BL/6) transgenic for a BAC insert containing the human CYP2C18 and CYP2C19 genes, which express both mRNA’s but only the CYP2C19 enzyme protein, have previously been produced and characterized with regards to basic phenotype.1, 2 In line with the inability of detecting CYP2C18 protein in the transgenic mice is the absence of the CYP2C18 enzyme also in human tissues.3, 4Hemizygous transgenic mice (CYP2C19Tg-Hem) display a specific motionphenotype, where one or both hind paws are lifted very high when walking.However, this locomotion pattern does not appear to present an obstacle for walking as we have not observed reduced locomotor activity in CYP2C19Tg-Hem compared to Wt mice.

Mice were group-housed with a 12-h light/dark cycle and ad libitum access to food and water. All experiments were approved by the local ethical committee; Stockholm Northern Ethics Board of Animal Experimentation.

CYP2C19Tg-Hem mice carry an estimated number of 12 copies of the human CYP2C18/19 genes 2 and CYP2C19Tg-Hem mice used in the current study were generated by crossing CYP2C19Tg-Hem with wild-type (Wt) mice. Wt litter mates were always used as controls. Homozygous (CYP2C19Tg-Hom) mice were only bred for investigations of embryonic and fetal development as these mice do not survive past post natal day 3 (PND3). Tail or ear biopsies were used for DNA extraction and genotyping analysis was performed by Transnetyx, Inc (Cordova, Tennessee, US) using primers designed before.2

CYP2C18 andCYP2C19expression in transgenic mice and human fetal brain

CYP2C19 and CYP2C18mRNAexpressionwas investigated in brain and liver tissue during embryonic development (embryonic day 14 (E14) and E18), early postnatal days (PND0 and PND7) and at 7 weeks of age. Brain and liver tissues were isolated and immediately placed in RNAlater RNA stabilizing solution (Qiagen). Human brain tissue was obtained from the NICHD Brain and Tissue Bank for Developmental Disorders at the University of Maryland, Baltimore, MD. Brain tissue samples were collected 1-12 hours post-mortem and frozen in isopentane/dry-ice and stored at -85°C. Brain tissues were obtained from 3 different female Caucasian donors; gestational week 19, 24 and 39. 2-3 cerebrum tissue pieces were obtained from each donor. All mouse and human tissues were homogenized using Zirconium oxide beads (0.5 mm) using the Bullet Blender™ (Next Advance, Inc., USA). RNA isolation and cDNA synthesis was performed according to the manufacturer´s recommendations using the RNeasy Mini Kit (Qiagen) and SuperScript III Reverse Transcriptase (Invitrogen). Real-time PCR protocol and primers were obtained from Löfgren et al,2except for the human housekeeping gene glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were the following primers were used: GAPDH- reverse:5´-GAT GGG ATT TCC ATT GAT GAC A andGAPDH- forward5´-CCA CCC ATG GCA AAT TCC.Data wereanalyzedusing the 7500 Fast System software (Applied Biosystems).

Brain morphology

Immediately after birth, PND0 pups were anesthetized with Ketamine/Xylacine (80/10 mg/kg, Intervet International/Bayer Healthcare) and perfused transcardially with phosphate buffered saline (PBS; 0.1 M, pH 7.4) with 5 IE/ml Heparin followed by 4% paraformaldehyde in 0.2M sodium phosphate buffer, pH 7.2. Mouse brains were removed and post-fixed over night at 4° C and cryoprotected in 20% and 30% sucrose for a total of 24 hours. Brains were snap-frozen and coronally sectioned at 40 µm using a cryostat (MICROM International GmbH, Walldorf, Germany). All sections were stained with cresyl violet and images were obtained using a Zeiss Axioskop 2 plus microscope with an Axiocam (Carl Zeiss HB, Stockholm, Sweden). Images were merged into whole brain images using the Photo merge function in Adobe Photoshop (Adobe Systems, San Jose, CA, USA). Sections were visually assessed to examine morphological changes, with the genotypes blinded to the investigator. For area measurements of different brain regions at PND0, sections from 3 CYP2C19Tg-Hom and 3 Wt mice were scanned with an Epson perfection V750 Pro scanner and the cortex, hippocampus and central regions were manually outlined in all sections using the pen tablet, Intuos4 (Wacom, Tokyo, Japan).The total area of each area was calculated in Adobe Photoshop as the number of pixels within the area selected.

To further investigate brain morphology, brains from 7 and 15 weeks old mice were prepared in the same way as described above for the PND0 pups. Every 7th section, starting approximately at Bregma -0.94 mm, was stained with crystal violet. A total of 12 coronal sections were stained in each animal, thus covering most of the hippocampal formation. All sections were scanned with an Epson perfection V750 Pro scanner and the hippocampi were manually outlined in all sections using the Lasso tool in Adobe Photoshop and the pen tablet, Intuos4(Wacom, Tokyo, Japan). The total area of each hippocampus was calculated in Adobe Photoshop as the number of pixels within the area selected. Brain and body weights were recorded in all perfused mice.

Magnetic resonance imaging

In vivomagnetic resonance imaging (MRI) experiments were conducted on CYP2C19Tg-Hem and Wt adult (15-weeks old) male mice using a horizontal 9.4 T Varian magnet equipped with a 12 cm inner diameter gradient system with a maximum gradient strength of 600 mT/m. A volume coil with an inner diameter of 30 mm and a resonator length of 40 mm of the millipede design was used (Varian, Inc. Abdington, UK). Animals were anaesthetized by isoflurane (5% for induction and then maintained at 1.25-1.75%) in a 1:9 mixture of O2and air.Mice were placed in prone position in a MR compatible animal holder with the head firmly fixed.Respiration rate was monitored and the body temperature was maintained at 37±0.5°C throughout the MRI experiment using a feedback controlled air-heater system (SA Instruments).The volumetric images were acquired using a 3D Inversion Recovery Fast Spin-Echo Sequence (Echo Train Length=4, kzero=1, inversion time=500 ms, repetition time/echo time=2.5s/5.46 ms, matrix size=128 x 128 x 64 covering a Field Of View of 20 x 18 x 10 mm3 in the caudal-cranial read out, left-right phase encode and inferior-superior phase encode 2 directions, respectively). The total scan time was of 1 h and 25 min per mouse.The data were zero filled by a factor of two in each dimension before Fourier transformed.Measurements of hippocampus and whole brain volumes (including cerebellum) were manually outlined using the image analysis software ITK-SNAP ( Mouse genotypes were blinded during the analysis.

BrdU injections and immunohistochemistry analyses of the hippocampus

For investigations of cell proliferation and cell survival in the hippocampus,6 7 weeks old mice were intraperitoneally injected with bromodeoxyuridine (BrdU, 75mg/kg). For proliferation assessments, mice were injected twice, with a 16 hours gap, and sacrificed by perfusion 2 hours after the last injection as described before. To investigate survival rates of proliferating cells, a second group of mice were injected once a day for 3 consecutive days and sacrificed by perfusion 4 weeks after the first injection. Brains and sections were prepared in the same way as described above. Every 7th section, starting approximately from Bregma -1.46 mm and totaling 8 sections per animal covering the whole hippocampal formation, was stained using a BrdU antibody. Staining for the proliferation marker Ki-67 was used as a control to validate BrdU stainings in 15 weeks old mice. For BrdU stainings, sections were pre-treated, to denature DNA with 1 % Triton X-100 in PBS for 15 minutes, 2 M Hydrochloric acid for 30 min at 37°C, and 0.1M Boric acid (pH 8.5) for 10 min. For all stainings, sections were then incubated for 2 hours in blocking solution (3 % Bovine Serum Albumin (Sigma), 0.25 % Triton X-100 (Sigma), 0.01 % NaN3 (Merck) in 0.1 M PBS) followed by over-night incubation with primary antibody at 4° C. Primary antibodies used were rat anti-BrdU (1:500; Accurate Chemical; Westbury, NY, USA) and rabbit anti-Ki-67 (1:500; Novocastra, Newcastle upon Tyne, UK). Sections were further incubated with fluorescent secondary antibodies (1:500) for 1.5 hours; anti-rat IgG Alexa Fluor™555 and anti-rabbit IgG Alexa Fluor™488 (Invitrogen). All immunohistochemical steps were performed free-floating and on 5-7 brains/genotype. Sections were mounted, dried and finally covered with ProLong® Gold Antifade with DAPI (Invitrogen).

For quantification of BrdU and Ki-67 positive cells, images were obtained using a Zeiss 710LSM laser scanning microscope (Carl Zeiss HB, Stockholm, Sweden). Positive cells were counted manually in all 8 hippocampal sections from each mouse using the count tool in Adobe Photoshop. All quantifications were performed by an investigator blind to mouse genotypes. To assess the number and structure of immature neurons in the DG of adult 15-week-old mice, sections were stained using a rabbit anti-double-cortin (DCX) (1:500 dilution; Abcam, Cambridge, UK) antibody and the ImmPRESS anti-rabbit Ig (peroxidase) polymer detection kit (Vector Laboratories, USA). Images were obtained using a Zeiss Axioskop 2 Plus microscope with an Axiocam (Carl Zeiss HB, Stockholm, Sweden) and cells were manually counted.

To further investigate hippocampal function,7, 8parvalbumin (PA) positive γ-aminobutyric acid (GABA)interneurons were calculated using IHC. Sections from 15-week-old mice were incubated with a primary mouse anti-PA antibody (1:1000 dilution; Swant, Bellinzona, Switzerland) using the protocol described for Ki-67 stainings above. Quantifications were performed by manual counting in the DG, CA1+2 and the CA3 regions of the mouse hippocampus.For all IHC markers, total numbers were also corrected for total hippocampal volumes as measured by MRI.

Behavioral tests

Behavioral tests were applied to Wt and CYP2C19Tg-Hem male mice at two different ages; adolescent (7-week-old) and adult (15-week-old) mice. All mice were handled by the experimenter once a day for four consecutive days before a specific test or test battery described below. Animals were always acclimatized to the test room at least one hour before behavioral sessions and tested during the light phase by an experimenter blind to their genotype.

The tail-suspension test (TST) was evaluated on two sets of CYP2C19Tg-Hem and Wt mice that were either only evaluated in this test(n=6-10 per group) or after exposure to the Morris water maze (MWM). MWMwas only employed on 15-week-old mice (Wt: n=10; CYP2C19Tg-Hem: n=9). The open-field (OF) andthe light-dark box (LDB)tests were performed consecutivelyon the same group of mice at both 7 and 15 weeks of age with at least three days between the tests (n=15 per group).

Tail-suspension test

Mice were suspended by the tail on a Plexiglas tablewith their head approximately 15 cm above the ground using an adhesive tape placed roughly 0.5 cm from the tip of the tail. The sessions were recorded using a video camera and immobility time was calculated manually for the whole 6-minute session. Mice were considered immobile when they hanged passively without moving.

Morris water maze

To asses spatial learning abilities of the CYP2C19Tg-Hem mice the MWM was employed.9The water maze had a diameter of 120 cm with a platform diameter of 10 cm and the water temperature was 23-25 °C. Four visual cues were placed around the pool. Mice were evaluated in a pre-training session with a visible platform to study motivation and swim capacity. Three days after the pre-training session,mice were trained for five consecutive days with four trials per day with an inter-trial interval of at least 20 minutes. Training sessions were performed with a hidden (transparent) platform in the north-west quadrant of the pool and the mice were randomly placed at four different starting positions per day; north, west, south and east.Three seconds on the platform was considered a successful response during the training sessions. If the platform was not located during the 90 second session time the mice were gently helped to the platform and required to stay for 10 seconds. In the retention test, performed without the platform oneday after the last training day,mice were placed in the south-east quadrant and left in the water for 60 seconds. Spatial learning was evaluated by measuring time to first platform crossing, number of total platform crossings and total time spent in the platform quadrant.

Open-field

To investigate spontaneous motor activity and response to a novel open space, mice were placed in the middle of a square open-field opaque Plexiglas box (50 cm3). No bedding was used and boxes were cleaned with 70 % ethanol between each trial. Each mouse was video-recorded for 30 minutes and videos were analyzed using the top-view based behavior analysis software TopScan Lite (Clever Sys Inc, Reston, Virginia). The open-field was divided into peripheral, intermediary and central regions. Distances traveled and time spent in each delimited area was recorded in 5-minute bouts.

Light-dark box

The light-dark box was used for assessing anxious behavior and consisted of two compartments: one dark, closed compartment (black Plexiglas) and one illuminated, open compartment (white Plexiglas). Both compartments measured 25 cm3 and were connected by an opening (10 cm wide and 5 cm tall) to allow animals to freely move from one compartment to the other.

Each individual mouse was gently placed in the light box facing away from the dark compartment and video-recorded for 5 minutes. Videos were analyzed using the top-view based behavior analysis software TopScan Lite (Clever Sys Inc, Reston, Virginia). Time spent in light and dark compartments and number of transitions between the compartments was recorded.

Effect of acute restraint stress on serum corticosterone levels and expression of c-fos in the hippocampus

Both 7- and 15-week-old mice were either decapitated directly without any prior stressor (control samples) or subjected to restraint stress for 30 minutes by use of ventilated 50 ml Falcon tubes. Mice subjected to restraint stress were removed from the tubes and either immediately decapitated or allowed to recover in their home cages for 30 minutes, after which they were decapitated. Corticosterone (CORT) quantifications were performed by an enzyme-linked immunosorbent assay specific for mouse/rat CORT according to the manufacturer’s instructions (ELISA, MBS494312, MyBiosource).

Hippocampi were dissected from all decapitated mice and placed in RNAlater solution (Qiagen). RNA isolation and cDNA synthesis was performed in the same way as described above. For mRNA quantification of the immediate-early gene (IEG) c-fos a Taqman assay from Applied Biosystems was employed (Cat No: Mm00487425_m1).

Supplementary Figure 1: Distribution of CYP2C19 mRNA expression in the brain

Relative CYP2C19 mRNA expression levels in three different brain regions at embryonic day 18 (E18) in 4 CYP2C19Tg-Hem embryos. To investigate the distribution of CYP2C19 mRNA expression during the embryonic peak at E18, the hippocampus, cortex and the rest of the cerebrum were dissected and processed for mRNA expression. The hippocampi were pooled from the four embryos due to their low weight. No significant differences in mRNA expression patterns were seen between the three regions. HC= hippocampi, *Cerebrum without cortex and hippocampus

Supplementary Figure 2: Size measurements in brain sections from CYP2C19Tg-Hom and Wt mice at PND0

Area measurements of cortex and hippocampus in brain sectionsof CYP2C19Tg-Hom and Wt mice in relation to whole brain area. Consecutive sections of brains from three Wt and three CYP2C19Tg-Hom mice were scanned with an Epson perfection V750 Pro scanner and the cortex and hippocampus were manually outlined in all sections using the pen tablet, Intuos4 (Wacom, Tokyo, Japan).The total area was calculated in Adobe Photoshop as the number of pixels within the selected area. The data are shown as in relation to whole brain volume and with mean Wt values set as 100%.Relative size reduction was 15% (p=0.029) and 61%(p=0.014) for the cortex and hippocampus, respectively.*p<0.05

Supplementary Figure 3: Brain weights of CYP2C19Tg-Hem mice and Wt controls

Brain weights of CYP2C19Tg-Hem mice and Wt controls. Brain weights were significantly lower in CYP2C19Tg-Hem mice compared to Wt controls at both 7 (5.4 %; p=0.007) and 15 (5.6 %; p=0.0004) weeks of age. Brain weights include the cerebellum and data are presented as mean with S.E.M. **p<0.01;***p<0.001

Supplementary Figure 4: BrdU and Ki-67 positive cells in the hippocampus

Seven-week-old mice were intraperitoneally injected with 75mg/kg bromodeoxyuridine (BrdU); either twice, with a 16 hours gap, and sacrificed 2 hours after the last injection (a), or injected once a day for 3 consecutive days and sacrificed 4 weeks after the first injection (b).Brain sections were stained by immunohistochemistry using Ki-67 or BrdU antibodies. (a) No difference in cell proliferation, as measured by BrdU and Ki-67 positive cells in the DG of the hippocampus were observed in 7- or 15-week-old mice. (b) There was furthermore no difference in number of surviving BrdU positive cells at 4 weeks after the final injection. Data are presented as mean with S.E.M.