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Interactions between different antidepressants and morphine alter gastrointestinal transit in mice
M M Backer1, S Schreiber, C G Pick
1Department of Anatomy and Anthropology, Sackler School of Medicine, Tel Aviv University, Israel.
Life Sciences
|January 1, 1997
Summary
Mianserin, a tetracyclic antidepressant, inhibits gastrointestinal transit independently of opioid receptors. Fluoxetine, a selective serotonin reuptake inhibitor, increased motility and only slightly reversed morphine-induced inhibition.
Area of Science:
- Pharmacology
- Neuroscience
- Gastroenterology
Background:
- Opioid analgesics like morphine can cause gastrointestinal (GI) dysfunction.
- Serotonergic antidepressants have complex interactions with the GI system and opioid receptors.
Purpose of the Study:
- To investigate the effects of mianserin and fluoxetine on morphine-induced GI inhibition.
- To elucidate the mechanisms underlying antidepressant-induced GI effects and their interaction with the opioid system.
Main Methods:
- Mice were pretreated with mianserin or fluoxetine before morphine administration.
- Gastrointestinal transit was measured to assess inhibitory or propulsive effects.
- Naloxone, an opioid antagonist, was used to differentiate receptor involvement.
Main Results:
- Mianserin alone caused dose-dependent GI inhibition, not reversed by naloxone.
- Fluoxetine alone increased GI propulsive motility, also not reversed by naloxone.
- Fluoxetine did not significantly alter mianserin-induced inhibition but mildly reversed morphine-induced inhibition.
Conclusions:
- Mianserin's GI inhibition involves non-opioid pathways.
- Fluoxetine's effects on GI motility are independent of opioid receptors.
- The serotoninergic system may play a role in modulating opioid effects on the GI tract.