Cytotoxic activity induced by the alkaloid extract from Ipomoea carnea on primary murine mixed glial cultures

Authors: CHOLICH, LUCIANA - National University Of The Northeast Argentina; PISTAN, MARIA - National University Of The Northeast Argentina; TORRES, ANA - National University Of The Northeast Argentina; ORTEGA, HUGO - Universidad Nacional Del Litoral; Gardner, Dale; BUSTILLO, SOLEDAD - National University Of The Northeast Argentina

Submitted to: Toxicon
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2020
Publication Date: 10/20/2020
Citation: Cholich, L.A., Pistan, M.E., Torres, A.M., Ortega, H.H., Gardner, D.R., Bustillo, S. 2020. Cytotoxic activity induced by the alkaloid extract from Ipomoea carnea on primary murine mixed glial cultures. Toxicon. 188:134-141. https://doi.org/10.1016/j.toxicon.2020.10.019.
DOI: https://doi.org/10.1016/j.toxicon.2020.10.019

Interpretive Summary: Ipomoea carnea is poisonous plant found throughout South America and temperate North America. The prolonged consumption of Ipomoea carnea produces neurologic disease in animals. The toxins in I. carnea are the alkaloids swainsonine and calystegines. In this study, an alternative cell culture assay was investigated to assess the toxic effects of the alkaloid extract of I. carnea. The primary brain cultures from newborn mouse containing mixed glial cells were exposed to Ipomoea extracts containing between 0 and 250 µM swainsonine for 48 h and the morphological changes investigated. It was found that those cells receiving higher concenctrations of swainsonine showed greater morphological changes. These findings suggest that swainsonine along with calystegines, are probably responsible for the activation of glial cells due to a possible lysosomal dysfunction and therefore intracellular storage. Our results demonstrate that this in vitro glial cell model is a very good alternative to in vivo studies that require several weeks of animal intoxication to observe similar neurotoxic effects.

Technical Abstract: The prolonged consumption of Ipomoea carnea produces neurologic symptoms in animals and a typical histological lesion, cytoplasmic vacuolization, especially in neurons. The toxic principles of I. carnea are the alkaloids swainsonine and calystegines B1, B2, B3 and C1. In this study, primary brain cultures from newborn mouse containing mixed glial cells were utilized. These cells were exposed to Ipomoea extracts containing between 0 and 250 µM swainsonine for 48 h. Morphological changes were investigated through Phase Contrast microscopy and Rosenfeld’s staining. The extract induced cytoplasmic vacuolization in astrocytes and microglia in a dose dependent manner, being more evident when cultures were exposed to 250 µM of swainsonine. In addition, acridine orange staining evidenced an increase in the number of lysosomes in both microglia and astrocytes cells. Consistent with this, scanning electron microscopy also showed that both types of cells presented morphological characteristics of cell activation. Ultrastructurally, cells showed vacuoles filled with amorphous material and surrounded by a single membrane and also multilayer membranes. Taken together, these findings suggest that swainsonine along with calystegines, are probably responsible for the activation of glial cells due to a possible lysosomal dysfunction and therefore intracellular storage. Our results demonstrate that this in vitro glial cell model is a very good alternative to in vivo studies that require several weeks of animal intoxication to observe similar neurotoxic effects.