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Central and peripheral minocycline suppresses motor activity in rats
O Kofman1, S van Embden, C Alpert
1Department of Behavioral Sciences, Ben Gurion University of the Negev, Beer-Sheva, Israel.
Abstract:
Minocycline (MIN) HCl is a tetracycline derivative previously shown to inhibit agonist-induced accumulation of cyclic adenosine monophosphate (cAMP) in vitro and suppress motor activity and amphetamine-induced hyperactivity in rats following SC injection. The present study examined the effect of IV and intracerebral MIN on baseline activity and amphetamine-induced hyperactivity. IV MIN suppressed both types of activity in doses of 100 and 150 mg/kg. When injected ICV, MIN (50 micrograms/2 microliter) suppressed the increase in rearing elicited by amphetamine but did not affect baseline activity. MIN did not attenuate the behavioral suppression induced by the cAMP phosphodiesterase inhibitor rolipram. MIN apparently has centrally mediated effects on motor activity in rats; however, it is not yet possible to associate MIN's behavioral effects with its ability to inhibit agonist-induced stimulation of cAMP.
Insights
Minocycline (MIN) HCl, a tetracycline derivative, reduces motor activity and amphetamine-induced hyperactivity in rats via central mechanisms. Its effects on cyclic adenosine monophosphate (cAMP) pathways require further investigation.
Area of Science:
- Neuropharmacology
- Behavioral Neuroscience
Background:
- Minocycline (MIN) HCl, a tetracycline derivative, is known to inhibit cyclic adenosine monophosphate (cAMP) accumulation in vitro.
- Previous studies indicate MIN suppresses motor activity and amphetamine-induced hyperactivity in rats after subcutaneous injection.
Purpose of the Study:
- To investigate the effects of intravenous (IV) and intracerebral (ICV) administration of MIN on baseline motor activity and amphetamine-induced hyperactivity in rats.
- To explore the potential involvement of cAMP pathways in MIN's behavioral effects.
Main Methods:
- Rats were administered MIN intravenously (100 and 150 mg/kg) or intracerebroventricularly (50 micrograms/2 microliter).
- Baseline activity, amphetamine-induced hyperactivity, and behavioral responses to the cAMP phosphodiesterase inhibitor rolipram were assessed.
Main Results:
- Intravenous MIN significantly suppressed both baseline activity and amphetamine-induced hyperactivity.
- Intracerebroventricular MIN reduced amphetamine-induced rearing but did not affect baseline activity.
- MIN did not alter the behavioral suppression caused by rolipram.
Conclusions:
- Minocycline exerts centrally mediated effects on motor activity in rats.
- The precise relationship between MIN's observed behavioral effects and its inhibition of agonist-induced cAMP stimulation remains unclear.