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. 2010 Oct 26;6:69.
doi: 10.1186/1744-8069-6-69.

Aromatase and 5-alpha Reductase Gene Expression: Modulation by Pain and Morphine Treatment in Male Rats

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Free PMC article

Aromatase and 5-alpha Reductase Gene Expression: Modulation by Pain and Morphine Treatment in Male Rats

Anna Maria Aloisi et al. Mol Pain. .
Free PMC article

Abstract

Background: The steroid hormone testosterone has been found to be greatly reduced by opioids in different experimental and clinical conditions. The purpose of this study on male rats was to determine the effects of a single injection of morphine (5 mg/Kg) on persistent pain (formalin test) and the single or combined effects on p450-aromatase and 5-alpha reductase type 1 mRNA expression in the brain, liver and testis. Testosterone was determined in the plasma and in the brain, morphine was assayed in the plasma.

Results: In the morphine-treated rats, there were increases of 5-alpha reductase mRNA expression in the liver and aromatase mRNA expression in the brain and gonads. Morphine was detected in the blood of all morphine-treated rats even though there were no clear analgesic affects in the formalin-treated animals three hours after treatment. Testosterone was greatly reduced in the plasma and brain in morphine-treated subjects.

Conclusions: It appears that morphine administration can induce long-lasting genomic effects in different body areas which contribute to the strong central and peripheral testosterone levels. These changes were not always accompanied by behavioral modifications.

Figures

Figure 1
Figure 1
Behaviors recorded during the formalin test (60 min). Spontaneous behaviors: (A) activity duration (sec) and (B) rearing frequency (n). Pain-related behaviors: (C) flexing duration, (D) licking duration and (E) paw-jerk frequency recorded in male rats treated with morphine (MOR) or saline (SAL) three hours before the formalin test in the dorsal hind paw. Data are shown as mean ± SEM.
Figure 2
Figure 2
Morphine levels in SHAM and FORM groups four hours after a single injection of morphine. Data are shown as mean ± SEM. Insert: calibration curve for morphine. The levels were comparable between the two groups.
Figure 3
Figure 3
Testosterone plasma (A) and brain (B) levels determined four hours after treatment in morphine (MOR)-treated animals and controls (SHAM); in formalin (FORM)-treated animals and controls (SHAM). Data are shown as mean ± SEM.
Figure 4
Figure 4
Relative mRNA expression of 5-alpha reductase type 1 and p450-aromatase in the diencephalon, liver and testis of the control group (SAL/SHAM). Liver is the reference organ, indicated as 1. Data are shown as mean ± SEM.
Figure 5
Figure 5
5-alpha reductase type 1 (A) and p450-aromatase (B) mRNA expression in the diencephalon, liver and testis. SAL/SHAM is the reference group, indicated as 1. Data are shown as mean ± SEM. Statistical significance vs SAL/SHAM *p < 0.05; **p < 0.01; ***p < 0.001.

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