10-oxo-trans-11-octadecenoic acid (KetoC) and 10-hydroxy-cis-12-octadecenoic acid (HYA) are long-chain fatty acids generated from linoleic acid by the gut lactic acid bacterium Lactobacillus plantarum. These fatty acids have been reported to have anti-inflammatory activity in the intestine. However, little is known about their effects in the brain. In this study, we aimed to investigate the effects of these fatty acids on lipopolysaccharide (LPS)-induced inflammatory processes in mouse microglial cells (BV-2 cells). KetoC and HYA inhibited LPS-induced nitric oxide (NO) production and suppressed the expression of inducible NO synthase in BV-2 cells. NO changes in these inhibitory effects were observed with AH7614, a G-protein coupled receptor 120 antagonist, or the peroxisome proliferator-activated receptors antagonists, GW6471 and GW9662. In addition, KetoC and HYA did not inhibit translocation of p65, a subunit of NF-κB, or IκB degradation. Similarly, no effect on p38 or JNK phosphorylation was observed. However, KetoC and HYA were found to inhibit ERK phosphorylation induced by LPS, suggesting that these fatty acids may exert their anti-inflammatory effects through the inhibition of ERK activation in microglial cells.

During development, dopaminergic neurons born in the substantia nigra extend their axons toward the striatum. However, the mechanisms by which the dopaminergic axons extend the striatum to innervate their targets remain unclear. We previously showed that paired-cultivation of mesencephalic cells containing dopaminergic neurons with striatal cells leads to the extension of dopaminergic neurites from the mesencephalic cell region to the striatal cell region. The present study shows that dopaminergic neurites extended along striatal neurons in the paired-cultures of mesencephalic cells with striatal cells. The extension of dopaminergic neurites was suppressed by the pharmacological inhibition of integrin α5β1. Using lentiviral vectors, short hairpin RNA (shRNA)-mediated knockdown of integrin α5 in dopaminergic neurons suppressed the neurite outgrowth to the striatal cell region. In contrast, the knockdown of integrin α5 in non-dopaminergic mesencephalic and striatal cells had no effect. Furthermore, overexpression of integrin α5 in dopaminergic neurons differentiated from embryonic stem cells enhanced their neurite outgrowth on striatal cells. These results indicate that integrin α5β1 expression on dopaminergic neurons plays an important role in the dopaminergic neurite outgrowth on striatal neurons.

Glutamate neurotoxicity is involved in various neurodegenerative disorders including brain ischemic stroke, trauma, and Alzheimer’s and Parkinson’s diseases. In addition to excitatory neuronal death, neuroinflammation accompanied by the activation of glial cells has been shown to be induced by these disorders. We previously reported the roles of nicotinic acetylcholine receptors (nAChRs) in the survival of central nervous system neurons during excitotoxic events and neuroinflammation. Nicotine and other nAChR agonists protected cortical neurons against glutamate neurotoxicity via α4- and α7-nAChRs in cultures of neurons obtained from the cerebral cortex of fetal rats. In addition, donepezil, a therapeutic acetylcholinesterase inhibitor currently being used for the treatment of Alzheimer’s disease, protected neuronal cells from glutamate neurotoxicity. Moreover, nicotine and donepezil induced the upregulation of nAChRs. Thus, we propose that nicotine as well as donepezil prevents glutamate neurotoxicity through Α4- and α7-nAChRs and the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. In addition to the beneficial effect on neuronal cells, we have reported the responses of astrocytes to bradykinin, an inflammatory mediator, and the effect of nAChR stimulation on these responses using cultured cortical astrocytes. Bradykinin induced a transient increase of intracellular calcium concentration ([Ca²⁺]_i) in cultured astrocytes. Both nicotine and donepezil reduced this bradykinin-induced [Ca²⁺]_i increase. This reduction was inhibited not only by mecamylamine, an nAChR antagonist, but also by PI3K and Akt inhibitors. These results suggest that nAChR stimulation suppresses the inflammatory response induced by bradykinin via the PI3K-Akt pathway in astrocytes.