Effects of extremely low frequency electromagnetic fields on morphine analgesia and tolerance in rats med./bio.

To examine the effects of exposure to a 50 Hz magnetic field on morphine analgesia and tolerance in rats.

A total of 78 male rats were utilized. Rats were examined after 1, 4, 7, 11, and 15 days of exposure and at 30 min intervals after injection of morphine (time points of 0, 30, 60, 90, and 120 minutes).
In a first experiment, the analgesic effects of magnetic field exposure alone were examined in four groups (n=6 per group): 1.1) control group, 1.2) 1 mT magnetic field, 1.3) 5 mT magnetic field, and 1.4) 10 mT magnetic field.
In a second experiment, the ideal morphine concentration was determined to be 5 mg/kg body weight.
In a third experiment, the effect of the magnetic field on morphine analgesia was tested (n=6 per group): 3.1) saline solution, 3.2) magnetic field (5 mT), 3.3) morphine (5mg/kg), 3.4) magnetic field (5 mT) + morphine (5 mg/kg).
In a fourth experiment, the effect of the magnetic field on morphine tolerance was tested. Morphium tolerance was induced with high doses of morphine over three days (30 to 120 mg/kg). Four groups were utilized (n=6 per group): 4.1) saline solution, 4.2) morphine tolerant, 4.3) magnetic field (no magnetic flux density given), and 4.4) magnetic field + morphine tolerant.

• animal
• rat/Wistar albino
• whole body

Remark EMF-Portal: The results of the tail flick test and hot plate test were very similar, which is why the following text always refers to both tests.
In the first experiment, the analgesic effect of the magnetic field was shown. In all magnetic field exposed groups (groups 1.2-1.4), the latencies to the first sign of pain were significantly higher than in the control group (group 1.1). The highest latencies were found in the group exposed to a magnetic field of 5 mT (group 1.3) and after 90 minutes (probably after exposure was finished).
In the third experiment, both a magnetic field (group 3.2) and morphine (group 3.3) significantly increased the latencies compared to the saline solution (group 3.1). Furthermore, a combination of morphine and the magnetic field (group 3.4) increased again the latencies compared to morphine alone (group 3.3).
In the fourth experiment, it was shown that both a magnetic field (group 4.2) and morphine in morphine tolerant group (group 4.3) significantly increased the latencies compared to the saline solution (group 4.1). Furthermore, a combination of morphine and the magnetic field in morphine tolerant rats (group 3.4) increased again the latencies compared to morphine alone in morphine tolerant rats (group 3.3).
The authors conclude that a 50 Hz magnetic field increases morphine analgesia and reduces morphine tolerance in rats.