In the central nervous system, astrocytes and microglia contribute to homeostasis, regulating the immune response to infectious agents. Neospora caninum is an obligate intracellular protozoan that infects different animal species and it is encysted in their nervous tissue while triggering an immune response modulated by glia. This study aimed to evaluate the infection of primary cultures of rat glial cells by N. caninum through the catabolites of tryptophan, the expression of inflammatory mediators and the integrity of neural tissue. Infection with this coccidium resulted in morphological and functional changes, particularly astrogliosis and microgliosis, and increased the expression of the inflammatory mediators TNF, IL1β, IL-10, and arginase, as well as mRNA for CCL5 and CCL2, molecules involved in the CNS chemotaxis. The infection with N. caninum in glial cells also triggered the activation of the tryptophan pathway, characterized by increased kynurenine 2,3 monooxygenase (KMO) mRNA expression, and by the production of the excitotoxin quinolinic acid (QUIN). Moreover, glia-neuron co-cultures, when exposed to the secretome derived from N. caninum infected glial cells, presented greater neurons distribution and formation of neurite extensions, associated to morphological changes in astrocytes compatible with neuro-preservation. Considering that the tryptophan catabolism is associated to immune response, these findings suggest that glial activation in N. caninum infection should be responsible for modulating the inflammatory status in an attempt to restore the nervous system homeostasis, since excessive inflammatory response can cause irreversible damage to tissue preservation.

Neosporosis is a disease caused by Neospora caninum sp (JP Dubey), an intracellular parasite that affects many animal species, fostering abortions and neurological disorders. Recent studies on Neospora caninum have shown that glial cells have been considered a model of in vitro infections of these protozoa. Honey has been used since ancient times for its anti-inflammatory and antimicrobial properties. The present study aimed to evaluate the in vitro reactivity of glial cells (astrocytes and microglia) infected with N. caninum treated with Jataí honey at 1% (Tetragonisca angustula). After 72 hours from infection, mitochondrial metabolism, dehydrogenase lactate activity (LDH), nitric oxide production (NO) and the number of parasites were checked. Cultures treated with honey at 1% have shown mitochondrial metabolism and cell permeability increase. There was an increase in nitrite production, possible indicating a microglial activation. Nitric Oxide values found in this study may indicate an immune response against Neospora caninum tachyzoites, since such increase may contribute to reduce the number of tachyzoites. So, our results suggest that honey had a protective effect over astrocytes and microglia cultures infected with Neospora caninum.