The impact of noradrenergic neurotoxin DSP-4 and noradrenaline transporter knockout (NET-KO) on the activity of liver cytochrome P450 3A (CYP3A) in male and female mice

Abstract

Background: Our earlier studies have shown that the brain noradrenergic system regulates cytochrome P450 (CYP) in rat liver via neuroendocrine mechanism. In the present work, a comparative study on the effect of intraperitoneal administration of the noradrenergic neurotoxin DSP-4 and the knockout of noradrenaline transporter (NET-KO) on the CYP3A in the liver of male and female mice was performed.

Methods: The experiments were conducted on C57BL/6J WT and NET^-/- male/female mice. DSP-4 was injected intraperitoneally as a single dose (50 mg/kg ip.) to WT mice. The activity of CYP3A was measured as the rate of 6β-hydroxylation of testosterone in liver microsomes. The CYP3A protein level was estimated by Western blotting.

Results: DSP-4 evoked a selective decrease in the noradrenaline level in the brain of male and female mice. At the same time, DSP-4 reduced the CYP3A activity in males, but not in females. The level of CYP3A protein was not changed. The NET knockout did not affect the CYP3A activity/protein in both sexes.

Conclusions: The results with DSP-4 treated mice showed sex-dependent differences in the regulation of liver CYP3A by the brain noradrenergic system (with only males being responsive), and revealed that the NET knockout did not affect CYP3A in both sexes. Further studies into the hypothalamic-pituitary-gonadal hormones in DSP-4 treated mice may explain sex-specific differences in CYP3A regulation, whereas investigation of monoaminergic receptor sensitivity in the hypothalamic/pituitary areas of NET^-/- mice will allow for understanding a lack of changes in the CYP3A activity in the NET-KO animals.

Keywords: Brain; Cytochrome P450; DSP-4 neurotoxin; Liver; NET knockout; Neuroendocrine regulation; Noradrenergic system.

Fig. 1

The influence of DSP-4 administration (50 mg/kg ip.) on the brain level of neurotransmitters in female (A) and male (B) mice. All values are shown as the mean ± SEM (n = 7–8). The results were evaluated statistically using Student’s t test: ****p < 0.0001, t = 9.047, df = 14 (females) and ****p < 0.0001, t = 5.839, df = 14 (males), compared to the control of the same sex. The mean numerical values and raw numerical data of neurotransmitter levels for each group are presented in the Table 1 of Supplementary materials

Fig. 2

The effect of DSP-4 administration (50 mg/kg ip.) on the CYP3A activity (A) and protein level (B) in the liver of male and female mice. All values are shown as the mean ± SEM (n = 7–8). The results were evaluated statistically using Student’s t test: *p < 0.05, t = 2.672, df = 13, compared to the control of the same sex. std standard. The mean numerical values and raw numerical data of enzyme activity for each group are presented in the Table 2 of Supplementary materials

Fig. 3

The pituitary level of growth hormone releasing hormone (GHRH) in control and DSP-4-treated male and female mice. All values are shown as the mean ± SEM (n = 7–8); the results were evaluated statistically using Student’s t test (no significance was found). The mean numerical values and raw numerical data of enzyme activity for each group are presented in the Table 3 of Supplementary materials

Fig. 4

The CYP3A activity (A) and protein level (B) in NET^+/+ (control) and NET^–/– (NE knockout) male and female mice. All values are shown as the mean ± SEM (n = 9–12); the results were evaluated statistically using Student’s t test (no significance was found). std standard. The mean numerical values and raw numerical data of enzyme activity for each group are presented in the Table 4 of Supplementary materials