Minocycline reduces prostaglandin E synthase expression and 8-isoprostane formation in LPS-activated primary rat microglia

Abstract

Minocycline is a tetracyclic antibiotic whose non-antibacterial activities, including anti-inflammatory, antinociceptive, and neuroprotective effects, have been widely studied. Thus, a better understanding of the mechanisms underlying its pleiotropic activities is important. Primary microglial cell cultures were established from cerebral cortices of 1-day neonatal Wistar rats. Minocycline (3–100 µM) or its vehicle was added to the culture media 30 min prior to 24 h incubation with lipopolysaccharide (LPS; 10 ng/mL). Cell viability after these treatments was assessed by ATP-based luminescence test. Prostaglandin (PG) E₂ and 8-iso-PGF_2α were determined by enzyme immunoassays. Cyclooxygenase-2 and microsomal PGE₂ synthase-1 protein levels were measured by western blot analysis. First, it was shown that minocycline (30 or 100 µM) inhibits PGE₂ production in LPS-activated primary rat microglial cells. Then, by investigating targets involved in this inhibition, it was found that minocycline (3–100 µM) inhibits microsomal PGE₂ synthase-1, but not cyclooxygenase-2, expression. Additionally, minocycline (3–100 µM) inhibited the production of 8-iso-PGF_2α. This study warrants the conduction of in vivo studies to evaluate the pharmacological relevance of these findings.

Keywords::

• Minocycline
• prostaglandin E₂
• cyclooxygenase-2
• microsomal prostaglandin E₂ synthase-1
• 8-isoprostane

Acknowledgement

The authors thank B. Guenter and U. Goetzinger-Berger for their technical assistance.

Declaration of interest

The authors report no conflicts of interest. A.C. de Oliveira was supported by CAPES (Brasília, Brazil).