Assessment of the perinatal effects of maternal ingestion of Ipomoea carnea in rats

Authors: HUEZA, ISIS - CEPTOX BRAZIL; GUERRA, JOSE - CEPTOX BRAZIL; HARAGUCHI, MITSUE - BIOLOGI. INST. SAO PAULO; Gardner, Dale; ASANO, NAOKI - HOKURIKU UNIV. JAPAN; IKEDA, KIOKO - HOKURIKU UNIV. JAPAN; GORNIAK, SLIVANA - CEPTOX BRAZIL

Submitted to: Experimental and Toxicologic Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2007
Publication Date: 4/6/2007
Citation: Hueza, I.M., Guerra, J., Haraguchi, M., Gardner, D.R., Asano, N., Ikeda, K., Gorniak, S.L. 2007. Assessment of the perinatal effects of maternal ingestion of Ipomoea carnea in rats. Experimental and Toxicologic Pathology, 58:439-446.

Interpretive Summary: Ipomoea carnea is an important poisonous plant occurring in many regions of South America and responsible for a large number of livestock poisonings in Brazil. It is believed that the toxin in I. carnea is the toxic alkaloid called swainsonine. Swainsonine is the toxin found in locoweeds found the western U.S. In the study here, perinatal work was performed to verify the transplacental passage of swainsonine and its excretion into milk. Female rats were treated with an aqueous extract of the plant known to contain swainsonine during gestation and after birth pups were fostered between treated and untreated dams. Pup body weight gain and histopathology to observe vacuolar degeneration was conduction along with swainsonine detection in amniotic fluid and milk from the rats. Pup body weight gain was significantly lower in pups from mothers treated with the plant and fostered to other treated mothers. The histopathology revealed that pups from treated mothers fostered to untreated ones showed the characteristic vacuolar lesions; however, the lesions from the pups from mothers treated with the plant and fostered to other treated mothers were more severe in both periods evaluated. Amniotic fluid and milk analysis revealed the presence of swainsonine excretion into these fluid compartments. Thus, it was concluded that swainsonine passes the placental barrier and affects both fetal development and nursing pups.

Technical Abstract: It is believed that I. carnea toxicosis induces abnormal embryogenesis in livestock. Studies with rats treated with I. carnea aqueous fraction (AF) during gestation, revealed litters with decreased body weight, but the characteristic vacuolar lesions promoted by swainsonine, its main toxic principle, were observed only in young rats on postnatal day (PND) 7. However, these alterations could have resulted as consequence of swainsonine placental passage and/or damage or even ingestion of the contaminated milk by pups. Thus, this perinatal work was performed to verify the transplacental passage of swainsonine and its excretion into milk employing the cross-fostering (CF) procedure as a tool of study. Females were treated with AF or vehicle during gestation and after birth pups were fostered between treated and untreated dams. Pup body weight gain (BWG) and histopathology to observe vacuolar degeneration were performed on PND 3 and 7. In addition, swainsonine detection was performed in amniotic fluid and milk from rats treated with the AF during gestation or lactation. BWG was significantly lower only in pups from mothers treated with the plant and fostered to other treated mothers (AF-AF group of pups). The histopathology revealed that pups from treated mothers fostered to untreated ones showed the characteristic vacuolar lesions; however, the lesions from the AF-AF pups were more severe in both periods evaluated. Amniotic fluid and milk analysis revealed the presence of swainsonine excretion into these fluid compartments. Thus, the results from CF and the chemical analysis allowed concluding that swainsonine passes the placental barrier and affects fetal development and milk excretion participates in I. carnea perinatal toxicosis.