Vitamin C Depletion in Prenatal Guinea Pigs as a Model of Lissencephaly Type II

Abstract

Humans and guinea pigs are unable to produce vitamin C, with deficiency resulting in a well-known disorder of collagen synthesis. Pial basement membrane structure preservation is essential in the proper migration of neurons. In our study, intrauterine deprivation of vitamin C in guinea pig fetuses led to a collagen synthesis disorder, weakness, and finally a breach of pial basement membrane. We found excessive migration of the external germinal layer cells into the subarachnoid space of the cerebellum through defects in the pial basement membrane. The changes ranged from focal rupture of pial basement membranes to their complete disintegration. The loss of proper folia formation resulted in macroscopically visible flattening of the cerebellar surface. Different grades of dysplastic changes in the folia of the cerebellar cortex were observed in 2 experimental groups assigned different limits to mark the time of commencement and duration of vitamin C deprivation. The most severe form of dysplastic changes was characterized by marked irregularity of the cerebellar cortex similar to that in lissencephaly type II. Thus, prenatal vitamin C deficiency represents a novel animal model to study the effects of collagen synthesis on development of breaches in the pial basement membrane, disordered migration of neurons, dysplasia of cerebellar cortex, and the pathogenesis of lissencephaly.Keywords scurvy, cerebellum, guinea pigs, vitamin c deficiency, lissencephaly, animal model Lissencephaly type II is a disease caused by alteration to the pial basement membrane (PBM) proteins, which causes it to weaken and become porous. This causes a deficiency of the glia limitans superficialis and radial glial cell connectivity. As a result, migrating neural cells pass through the pial gaps to form cell ectopia near the brain surface. This leads to loss of gyri and sulci, forming irregularities on the brain surface and a so-called cobbled formation, which is why lissencephaly type II is also sometimes called cobblestone lissencephaly. 9,34Based on the fact that the structural integrity of the PBM is necessary for proper migration of the neurons, 2 main approaches have been established for experimental modeling of lissencephaly type II. First, animal models with targeted inactivation of genes involved in membrane protein synthesis have been studied. The lack of these proteins, such as collagen, laminin, and others, causes the PBM to weaken and finally rupture. 13,16,17,25,43 The second approach uses chemical destruction of meningeal cells over the developing cerebellum through exposure to 6-hydroxydopamine (6-OHDA). The loss of glio-pial membrane allows for overmigration of neurons through the pial breaches into the subarachnoid space. 1,29,30 Collagen is one of the key structural units of the basement membrane, and its synthesis is dependent on vitamin C. Humans, monkeys, and guinea pigs are unable to synthesize vitamin C because of a lack of L-gulono-g-lactone oxidase. 27It is well known that a deficiency of vitamin C in guinea...

Prenatal treatment with metronidazole induces cerebellar folia alteration in guinea pig fetuses

“…The foliation itself and the final fixed number of 10 folia point to the genetic basis of this process in which the complexity and number of subsegments increases in evolutionarily higher mammalian species [24,40]. Several chemicals [2][3][4][5], radiation [6], the absence of nutritional factors [7,8] as well as genetic mutations [41,42] are linked to the disturbance in the cerebellar cortex and folia development. Changes such as hypofissure, malposition and agenesis of the folia usually dominate.…”

“…On the 50 th day of gestation (at 8 a.m.), the fetuses (19 in the E, and 20 in the C group) were removed by Cesarean section under urethane anesthesia (1.0 g/kg) and then weighed. Cardiopuncture was performed to collect the blood and the whole body was fixed by perfusion fixation protocol previously described [7]. After fixation, the central nervous structures (cerebrum, cerebellum, medulla oblongata and spinal cord) were removed and immersed in Zamboni fixative for 24 h at 4°C.…”

“…The first findings of neuronal migration based on neuronal-glial interaction were described in a cerebellar development model [1]. Due to its specific structure, the cerebellum has so far been the subject of numerous studies examining the neurotoxic potential of different chemicals [2][3][4][5], ionizing radiation [6], as well as deficiencies of specific nutritional factors [7,8].…”

Prenatal assessment of cerebellar vermian lobulation: fetal MRI with 3‐Tesla postmortem validation

“…Abnormalities of fetal vermian foliation are frequently associated with deviations of fissuration (Figure ). The pathological genetic, molecular and cellular mechanisms that cause abnormal fissuration and foliation are becoming better understood. In addition, infections or teratogenic‐toxic effects, such as fetal alcohol, cocaine or retinoic acid exposure, may result in abnormal foliation and fissuration.…”

Combatting the Myth of Neuropathology

“…The study by Capo et al represents an excellent example of long-term effects of vitamin C depletion in prenatal guinea pigs. 5 Observed dysplastic changes are reminiscent of lissencephaly type II, indicating that morphologic manifestation induced by dietary imbalances may mimic malformations due to gene defects. The role of neurotoxins as a trigger of neuropathologic changes in the developing and adult CNS is well known but difficult to prove in spontaneous cases.…”