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Published on: March 28, 2017
CYP2D1 Gene Knockout Reduces the Metabolism and Efficacy of Venlafaxine in Rats
Hongqiu Zhou1, Li Yang1, Changsuo Wang1
1School of Pharmacy, Jiangsu University, Zhenjiang, Jiangsu, China (H.Z., L.Y., C.W., Z.L., Z.O., Y.W.); MtC BioPharma Co. Ltd., Nanjing, Jiangsu, China (M.S.); and Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany, Albany, New York (J.G.).
Abstract:
Rat CYP2D1 has been considered as an ortholog of human CYP2D6 To assess the role of CYP2D1 in physiologic processes and drug metabolism, a CYP2D1-null rat model was generated with a CRISPR/Cas9 method. Seven base pairs were deleted from exon 4 of CYP2D1 of Sprague-Dawley wild-type (WT) rats. The CYP2D1-null rats were viable and showed no abnormalities in general appearance and behavior. The metabolism of venlafaxine (VLF) was further studied in CYP2D1-null rats. The V max and intrinsic clearance of the liver microsomes in vitro from CYP2D1-null rats were decreased (by ∼46% and ∼57% in males and ∼47% and ∼58% in females, respectively), while the Michaelis constant was increased (by ∼24% in males and ∼25% in females) compared with WT rats. In the pharmacokinetic studies, compared with WT rats, VLF in CYP2D1-null rats had significantly lower apparent total clearance and apparent volume of distribution (decreased by ∼36% and ∼48% in males and ∼23% and ∼25% in females, respectively), significantly increased area under the curve (AUC) from the time of administration to the last time point, AUC from the start of administration to the theoretical extrapolation, and C max (increased by ∼64%, ∼59%, and ∼26% in males and ∼43%, ∼35%, and ∼15% in females, respectively). In addition, O-desmethyl venlafaxine formation was reduced as well in CYP2D1-null rats compared with that in WT rats. Rat depression models were developed with CYP2D1-null and WT rats by feeding them separately and exposing them to chronic mild stimulation. VLF showed better efficacy in the WT depression rats compared with that in the CYP2D1-null rats. In conclusion, a CYP2D1-null rat model was successfully generated, and CYP2D1 was found to play a certain role in the metabolism and efficacy of venlafaxine. SIGNIFICANCE STATEMENT: A novel CYP2D1-null rat model was generated using CRISPR/Cas9 technology, and it was found to be a valuable tool in the study of the in vivo function of human CYP2D6. Moreover, our data suggest that the reduced O-desmethyl venlafaxine formation was associated with a lower VLF efficacy in rats.
Insights
A new rat model lacking CYP2D1 was created using CRISPR/Cas9. This model revealed CYP2D1
Area of Science:
- Pharmacology
- Genetics
- Biochemistry
Background:
- Cytochrome P450 2D1 (CYP2D1) in rats is considered an ortholog of human Cytochrome P450 2D6 (CYP2D6).
- Understanding CYP2D1's role in physiological processes and drug metabolism is crucial for translational research.
- A specific rat model is needed to investigate the in vivo functions of CYP2D1.
Purpose of the Study:
- To generate a CYP2D1-null rat model using CRISPR/Cas9 gene-editing technology.
- To investigate the role of CYP2D1 in the metabolism and pharmacokinetics of venlafaxine (VLF).
- To evaluate the impact of CYP2D1 deficiency on venlafaxine efficacy in a rat depression model.
Main Methods:
- CRISPR/Cas9 gene editing was employed to delete seven base pairs from exon 4 of the CYP2D1 gene in Sprague-Dawley rats.
- In vitro studies using liver microsomes assessed Vmax, Km, and intrinsic clearance of venlafaxine metabolism.
- In vivo pharmacokinetic studies measured VLF clearance, volume of distribution, AUC, and Cmax in wild-type (WT) and CYP2D1-null rats.
- A rat depression model was established to compare venlafaxine efficacy between WT and CYP2D1-null rats.
Main Results:
- CYP2D1-null rats were viable and exhibited no gross abnormalities.
- In vitro and in vivo studies demonstrated significantly altered venlafaxine metabolism and pharmacokinetics in CYP2D1-null rats compared to WT rats, including reduced Vmax, intrinsic clearance, and apparent total clearance, alongside increased AUC and Cmax.
- O-desmethyl venlafaxine formation was reduced in CYP2D1-null rats, correlating with lower venlafaxine efficacy in a depression model.
Conclusions:
- A functional CYP2D1-null rat model was successfully generated, providing a valuable tool for studying CYP2D1 and human CYP2D6 in vivo.
- CYP2D1 plays a significant role in venlafaxine metabolism and efficacy.
- Reduced O-desmethyl venlafaxine formation in CYP2D1-null rats is associated with diminished venlafaxine therapeutic effects.
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