Exposure to opiates in male adolescent rats alters pain perception in the male offspring

Abstract

During the past decades, the use/misuse of opioids has increased dramatically among adolescent population. It is now well acknowledged that various morphological and physiological changes occur in the brain during adolescence. During this critical period, brain development and maturation could be affected by several factors including stress, drug abuse, nutritional status, etc. Although studies on transgenerational effects of substances such as alcohol, nicotine, and cocaine have focused on both paternal and maternal drug exposure, most reports on transgenerational effects of morphine are restricted to maternal exposure. Thus, in this study, we aimed to investigate the transgenerational effect of paternal morphine exposure during adolescence on pain perception and antinociceptive effect of morphine in rat offspring. Male rats received escalating doses of morphine for 10 days during postnatal days 31-40. Twenty days after the last morphine injection, male rats were mated with intact female rats, and then behavioral tests were conducted on the male offspring on postnatal day 60. Pain perception and morphine antinociception were evaluated using the formalin test. Our results demonstrated that morphine-sired and saline-sired animals differed in the interphase and phase 2 of the formalin test. These findings indicate a significant transgenerational effect of paternal morphine exposure on pain-related behaviors in rat offspring.

Adolescent morphine exposure increases nociceptive behaviors in rat model of formalin test

“…We have recently demonstrated in our previous research that morphine administration during adolescence makes transgenerational effect on pain perception in the offspring. By using the same experiment, that is, formalin test, we reported that the duration of interphase significantly decreased in morphine‐sired animals compared to saline‐sired ones (Pachenari, Azizi, Ghasemi, Azadi, & Semnanian, ). The results of long‐term and transgenerational effect of adolescent morphine exposure on pain perception which are described in the current and mentioned studies, respectively, are not exactly the same.…”

“…The reason we opted for this dose was that, in our previous laboratory study, it was observed that injection of 2.5 mg/kg morphine significantly alters analgesic response of adolescent morphine‐treated animals compared to the saline‐treated counterparts in tail flick test during adulthood (data not published). Moreover, we observed that adolescent morphine exposure made no significant transgenerational effect on analgesic response to 2.5 mg/kg morphine injection in rat model of formalin test (Pachenari et al, ), so we aimed to compare the long‐term and transgenerational effect of morphine analgesia by using formalin test.…”

The effect of intravenous administration of liposomal curcumin in addition to sumatriptan treatment in an experimental migraine model in rats

“…Despite its limitations, the formalin test is still currently used in the evaluation of both pain and inflammation in animal models. 76,77 Second, the concentration of curcumin and/or ST in the blood, as well as in the brain tissue, was not quantified. This kind of measurements could bring useful information, but a separate design using different forms of curcumin must be tested.…”

Multigenerational and transgenerational effects of paternal exposure to drugs of abuse on behavioral and neural function

“…Therefore, assessing antinociceptive properties of opioids can serve as a proxy for understanding opioid reward. A recent study showed that chronic morphine treatment in Wistar rat sires did not affect morphine-induced antinocieption in the offspring as assessed by the formalin pain test (Pachenari et al, 2018). However, in a separate study, exposure to a single dose of morphine in adult male Sprague Dawley rats prior to breeding resulted in F1 male offspring that exhibited enhanced antinociceptive effects of morphine in the hot plate assay (Cicero et al, 1995).…”