Using Advanced Imaging Methods to Study Neurolathyrism.

BACKGROUND: Neurolathyrism is a toxic nutritional disorder caused by consumption of the grass pea, Lathyrus sativus. The disease, which manifests as an acute or insidiously evolving spastic paraparesis, continues to occur throughout Africa and Asia. Research on this disease is limited, and to our knowledge no imaging studies of patients with neurolathyrism have been published. OBJECTIVES: To better localize the site of damage in neurolathyrism using advanced imaging methods. METHODS: Three male patients, immigrants from Ethiopia, were included in the study. All had a history of arrested spastic paraparesis that had evolved before their emigration from Ethiopia, and a past history of exposure to grass pea without any other cause. Functional magnetic resonance imaging (fMRI) included simple motor tasks to evaluate cortical motor areas. Anatomic scans included diffusion tensor imaging (DTI) to evaluate the corticospinal tracts. RESULTS: In all patients clear activation was found in motor regions, and the patients' activity pattern was qualitatively similar to that in control sublects. In one patient in whom clinical symptoms were asymmetric, an asymmetric activity pattern in Ml was identified. DTI analysis identified intact corticospinal tracts connecting the pons and the primary motor regions, similar to control subjects. CONCLUSIONS: Advanced neuroimaging clearly identified well-functioning motor regions and tracts in neurolathyrism patients, suggesting a spinal etiology.

Lessons from neurolathyrism: a disease of the past & the future of Lathyrus sativus (Khesari dal).

Neurolathyrism is past history in India since Lathyrus sativus (khesari dal) is no longer used as a staple. A consensus has evolved that khesari dal is harmless as part of a normal diet. L-ODAP (ß-N-oxalyl-l-α-diamino propionic acid) the neurotoxic amino acid, from this pulse, is detoxified in humans but not in animals but still no laboratory animal is susceptible to it under acceptable feeding regimens. L-ODAP is an activator of protein kinase C and consequential crucial downstream effects such as stabilization of hypoxia inducible factor-1 (HIF-1) could be extremely conducive to humans under a variety of situations. ODAP is gradually finding a place in several patents for this reason. Homoarginine the second amino acid from L. sativus can be a better substrate for endogenous generation of nitric oxide, a crucial signaling molecule associated with the cardiovasculature and control of hypertension. These features could make L. sativus a prized commodity as a functional food for the general cardiovasculature and overcome hypoxic events and is set to change the entire perception of this pulse and neurolathyrism.

The nutritive value of grasspea (Lathyrus sativus) and allied species, their toxicity to animals and the role of malnutrition in neurolathyrism.

The safe use of grasspea (Lathyrus sativus) and allied species (L. cicera, L. clymenum and L. ochrus) requires a better understanding of the factors that are involved in the development of neurolathyrism. A suitable animal model is needed. The nutritional quality, seed chemical composition, the role of malnutrition, synergistic action of antinutritional factors, the toxicity of both seed and forage to animals, metabolism and tissue distribution of the toxic amino acid beta-N-oxalyl-alpha,beta-L-diaminopropionic acid (ODAP) in mammals are reviewed. Malnutrition is not necessary for the development of neurolathyrism, however, the supply of sulfur amino acids by Lathyrus spp. is limited by the combined action of several antinutritional factors and the low inherent levels in the seeds. Metabolism or excretion of ODAP and clearance from the central nervous system appear to function well under normal circumstances, while species differences exist. Interruptions to these processes and excessive concurrent demands for reduced sulfur amino acids are likely to be conducive to the onset of neurotoxicity.

Climatic, edaphic and altitudinal factors affecting yield and toxicity of Lathyrus sativus grown at five locations in Ethiopia.

A 2 years (2005-2006) data analysis based on agronomic, qualitative, climatic and edaphic factors was carried out using 10 grass pea (Lathyrus sativus L.) genotypes grown at five eco-divergent locations (Alem Tena, Debre Zeit, Denbi, Akaki, Chefe Donsa) in Ethiopia. Crop yield showed considerable variability among locations, years and genotypes. Path coefficient analysis indicated that rainfall and days to maturity have a large positive influence on yield. High level of micronutrients Mn(2+) and S(2-) negatively affected yield. Path analysis revealed that Zn(2+)/P, days to maturity, yield and K(+) were dominant variables affecting the response variable ß-ODAP (ß-N-oxalyl-L-α,ß-diaminopropionic acid), the neuro-excitatory amino acid in grass pea seeds considered as the cause of neurolathyrism. Linear correlation analysis between ß-ODAP and the 35 factors considered showed that ß-ODAP level was positively correlated (r > 0.70) with K(+) and sunshine hours (ssh) and negatively correlated (r < 0.70) with soil pH, days to maturity and yield. The strongest correlation of ssh with ß-ODAP level was found during the phase of crop maturity. Our results suggest that ß-ODAP biosynthesis and its response to environmental stress are maximized during the post-anthesis stage.

Towards the re-introduction of grass pea (Lathyrus sativus) in the West Balkan Countries: the case of Serbia and Srpska (Bosnia and Herzegovina).

Vetchlings (Lathyrus spp.) are widely distributed in both Serbia and Srpska, and represent a valuable component of local floras all over the Balkan Peninsula. Despite this and the existence of a traditional Serbian name for grass pea (Lathyrus sativus L.), sastrica, and a pan-Slavic name for all vetchlings, grahor, today they are almost forgotten crops. The joint action of the Institute of Field and Vegetable Crops and the Faculty of Agriculture is aimed at re-introducing grass pea and other vetchlings as multifunctional crops. Within the legume collection in the Institute of Field and Vegetable Crops, a small Lathyrus spp. collection, including about 100 accessions of 16 species, most of them being grass pea, was established in 2002. The landraces of grass pea were collected in several regions of Serbia and Srpska, where they are used for human consumption. Grass pea is commonly used boiled and along with other pulses, with no reports on lathyrism among the local people. The first Serbian breeding programme in Novi Sad produced already two grass pea lines that were registered in November 2009 under the names of Studenica and Sitnica, developed from the crosses of Polish cultivars and local Serbian landraces.

Toxicity of non-protein amino acids to humans and domestic animals.

Non-protein amino acids are common in plants and are present in widely consumed animal feeds and human foods such as alfalfa (Medicago sativa), which contains canavanine, and lentil (Lens culinaris), which contains homoarginine. Some occur in wild species that are inadvertently harvested with crop species. Some non-protein amino acids and metabolites can be toxic to humans, e.g. Lathyrus species contain a neurotoxic oxalyl-amino acid. Some potential toxins may be passed along a food chain via animal intermediates. The increased interest in herbal medicines in the Western countries will increase exposure to such compounds.

Effect of methionine supplement on physical responses and neurological symptoms in broiler chicks fed grass pea (Lathyrus sativus)-based starter ration.

Starter feeding experiments of broiler chicks with raw grass pea (Lathyrus sativus L.) supplemented with different levels of DL-methionine were undertaken for 4 weeks to assess the toxicity of grass pea-based feed and to correlate it with neurological symptoms. Four hundred fifty day-old broiler chicks were divided into two groups and were given formulations containing 35% (ration I) or 98.5% (ration II) grass pea, respectively. Each ration included controls and treatments with added methionine of four different concentrations. Feed intake, weight gain and feed conversion efficiency (FCE) were much higher in ration I than in ration II and these parameters significantly improved by addition of methionine in both rations. Significant increase of neurological signs with higher grass pea intake and significant reduction of acute neurological signs with addition of methionine were observed. Tolerance for grass pea was enhanced with increasing methionine in the diet and with age. Despite a similarity in the initial intake, a significant (p0.05) increase in the final feed intake by the chicks with methionine addition was found in both rations. These results suggest that methionine can improve a grass pea-based diet for broiler chicks and especially can protect young chicks from neurological symptoms.

Metabolism of dietary ODAP in humans may be responsible for the low incidence of neurolathyrism.

OBJECTIVES: The reasons for the very low incidence of the disease neurolathyrism in humans even after excessive consumption of the pulse, Lathyrus sativus, under severe drought and famine conditions, and its continued consumption by large populations during normal periods without any deleterious effects have been examined in the context of a possible metabolism or detoxification of beta-N-oxalyl-L-alpha, beta-diaminopropionic acid (ODAP), the major neurotoxic amino acid of L. sativus. DESIGN AND METHODS: ODAP in urine samples from 54 subjects habitually consuming the pulse and in three volunteers on an L. sativus diet was determined by the OPT method following clean up of the samples on an alumina column. Urinary oxalate was also determined in these individuals. RESULTS: Twenty-five subjects showed no excretion of ODAP and it was only less than 0.7% of the dietary intake in the remaining 29 subjects. Urinary excretion of ODAP in three volunteers was also less than 1% with a peak excretion in the 4-h sample. The 4-h blood sample from one volunteer had a maximum ODAP concentration of 177 microM. The urinary oxalate content in the volunteers was nearly 3-fold higher compared to controls. CONCLUSIONS: The low excretion of dietary ingested ODAP in humans is in sharp contrast to that seen in animals and indicates a metabolism or detoxification of ODAP which may be unique to humans and may explain the low incidence of neurolathyrism.

Comparative effect of dietary administration of Lathyrus sativus pulse on behaviour, neurotransmitter receptors and membrane permeability in rats and guinea pigs.

Neurolathyrism, an upper motor neuron disease, has been thought to be caused by long-term dietary consumption of lathyrus pulse, which contains the toxin beta-N-oxalyl-L-alpha,beta-diaminopropionic acid. Earlier behavioural studies employing oral feeding of lathyrus pulse to animals has been conducted without evaluating the biochemical toxicity potential. In the present investigation the effect of dietary feeding of 10%, 50% and 80% lathyrus pulse to rats and guinea pigs for 3 months on neurobehavioural parameters, including locomotor activity, inclined plain test and neurotoxicological parameters such as neurotransmitter receptor binding, Ca(2+) influx and membrane fluidity, was investigated. Exposure of 50% low and high toxin lathyrus to rats did not cause any significant change in locomotor activity, whereas guinea pigs at the same dosage regimen of high toxin lathyrus showed significant lowering of inclined plain test scores. Furthermore, studies of neuroreceptor binding in rats fed 50% low and high toxin lathyrus showed significant changes in glutamate, dopamine and muscarinic receptors, whereas the benzodiazepine receptor elicited no change. Guinea pigs, on the other hand, fed 50% and 80% lathyrus in the diet showed significant changes in glutamate, dopamine, muscarinic and benzodiazepine receptors. Interestingly, significant elevation in intracellular calcium with a concomitant increase in membrane fluidity was observed in rats (50% low and high toxin) and guinea pigs (50% and 80%) fed a lathyrus diet. These results indicate that although both species (rats and guinea pigs) are susceptible to neurochemical changes on exposure to lathyrus, locomotor changes are only noticed in guinea pigs. Thus, guinea pigs may be more prone to lathyrus toxicity and may serve as a sensitive animal model compared with rats.