Rat Model Of Infantile Spasms Research Articles

Gut-based manipulations spur hippocampal mitochondrial bioenergetics in a model of pediatric epilepsy

A growing body of evidence supports a role of the gut microbiota in regulating diverse physiological processes, including neural function and metabolism via the gut-brain axis. Infantile spasms syndrome is an early-onset epileptic encephalopathy associated with perturbed brain mitochondrial bioenergetics. Employing a neonatal rat model of infantile spasms, mitochondria respirometry and biochemical analyses, the present study reveals that gut microbiota manipulation by diet, antibiotics and probiotics have the potential to enhance hippocampal mitochondrial bioenergetics. Although preliminary in nature, our data reveal that microbial manipulation that regulates brain mitochondrial function may be a novel strategy for the treatment of epileptic disorders.

Isovaline efficacy in a rat pup model of infantile spasms.

Infantile spasms, also known as epileptic spasms during infancy, is an epileptic disorder of infancy and early childhood that is associated with developmental delay or regression, high mortality rate and is difficult to treat with conventional antiseizure medication. Previously, we reported that a unique amino acid called isovaline had potent anticonvulsive efficacy in the 4-aminopyridine and pilocarpine rat models of seizures. In this study, we examined whether isovaline possess therapeutic utility in a well-established rat model of infantile spasms which involves the pretreatment of a pregnant dam with betamethasone and subsequent induction of spasms with N-methyl-D-asparate (NMDA), a glutamate receptor agonist, in 15-day old pups. We treated seven of these pups with saline prior to administering NMDA and eight of these pups with isovaline (300 mg/kg) intraperitoneal (i.p.) prior to NMDA. Isovaline significantly reduced the number of full-body jumps from 18.1 ± 5.0 to 6.3 ± 1.8 and leg/arm/tail strains from 4.4 ± 1.6 to 1.1 ± 0.5. A trend in a reduction of body twitch was noted in rat pups administered isovaline (P = 0.05), but no significant difference was seen in NMDA-induced head nods (P = 0.221). In conclusion, our data demonstrate a potential for isovaline to attenuate an aggressive form of epilepsy that typically requires highly toxic medications to treat in children.

Acquired parvalbumin-selective interneuronopathy in the multiple-hit model of infantile spasms: A putative basis for the partial responsiveness to vigabatrin analogs?

SummaryWest syndrome, an age‐specific epileptic encephalopathy, manifests with infantile spasms (IS) and impaired neurodevelopmental outcomes and epilepsy. The multiple‐hit rat model of IS is a chronic model of IS due to structural etiology, in which spasms respond partially to vigabatrin analogs. Using this model, we investigated whether IS due to structural etiology may have deficits in parvalbumin (PRV) and somatostatin (SST) immunoreactive (‐ir) interneurons, and calretinin‐ir (CR‐ir) neurons of the primary somatosensory cortex of postnatal day (PN) 20–24 rats, using specific immunohistochemical assays. PN3 Sprague‐Dawley male rats underwent the multiple‐hit induction protocol, were monitored until PN20–24, and were transcardially perfused to collect brains for histology. Age‐matched sham and naive control male rats were also used. Coronal brain cryosections were stained with anti‐PRV, anti‐CR, and anti‐SST antibodies, and regions of interest (ROIs) from the primary somatosensory cortices were selected to determine PRV‐, CR‐, and SST‐ir cell counts and cortical ROI volumes, with blinding to experimental group. Statistical analyses were done using a linear mixed model accounting for repeated measures. We found PRV‐ir interneuronal selective reduction, sparing of the CR‐ir and SST‐ir neurons, and bilateral cortical atrophy. Our findings provide evidence for acquired PRV‐selective interneuronopathy, possibly underlying the pathogenesis of IS, neurodevelopmental deficits, and epilepsy, and potentially contributing to the partial response to vigabatrin analogs in this model.

In Vivo Multimodal Magnetic Resonance Imaging Changes After N-Methyl-d-Aspartate-Triggered Spasms in Infant Rats.

Despite the serious neurodevelopmental sequelae of epileptic encephalopathy during infancy, the pathomechanisms involved remain unclear. To find potential biomarkers that can reflect the pathogenesis of epileptic encephalopathy, we explored the neurometabolic and microstructural sequelae after infantile spasms using a rat model of infantile spasms and in vivo magnetic resonance imaging techniques. Rats prenatally exposed to betamethasone were subjected to three rounds of intraperitoneal N-methyl-d-aspartate (NMDA) triggering of spasms or received saline injections (controls) on postnatal days (P) 12, 13, and 15. Chemical exchange saturation transfer imaging of glutamate (GluCEST) were performed at P15 and 22 and diffusion tensor imaging and additional spectroscopy (1H-MRI/MRS) of the cingulate cortex were serially done at P16, 23, and 30 and analyzed. Pathological analysis and western blotting were performed with rats sacrificed on P35. Within 24 h of the three rounds of NMDA-induced spasms, there was an acute increase in the GluCEST (%) in the cortex, hippocampus, and striatum. When focused on the cingulate cortex, mean diffusivity (MD) was significantly decreased during the acute period after multiple spasms with an increase in γ-aminobutyric acid (GABA), glutamate, and glutamine N-acetylaspartate-plus-N-acetylaspartylglutamate (tNAA), total choline, and total creatine. The juvenile rats also showed decreased MD on diffusion tensor imaging and significant decreases in taurine, tNAA, and macromolecules-plus-lipids in the cingulate cortex. Pathologically, there was a significant reduction in glial fibrillary acidic protein, myelin basic protein, and neuronal nuclei expression in the cingulate cortex of rats with NMDA-induced spasms. These neurometabolic and microstructural alterations after NMDA-triggered spasms might be potential imaging biomarkers of epileptic encephalopathy.

ACTH and PMX53 recover synaptic transcriptome alterations in a rat model of infantile spasms

We profiled the gene expression in the hypothalamic arcuate nuclei (ARC) of 20 male and 20 female rats to determine the infantile spasms (IS) related transcriptomic alteration of neurotransmission and recovery following two treatments. Rats were prenatally exposed to betamethasone or saline followed by repeated postnatal subjection to NMDA-triggered IS. Rats with spasms were treated with ACTH, PMX53 or saline. Since ACTH, the first line treatment for IS, has inconsistent efficacy and potential harsh side effects, PMX53, a potent complement C5ar1 antagonist, was suggested as a therapeutic alternative given its effects in other epilepsy models. Novel measures that consider all genes and are not affected by arbitrary cut-offs were used, in addition to standard statistical tests, to quantify regulation and recovery of glutamatergic, GABAergic, cholinergic, dopaminergic and serotonergic pathways. Although IS alters expression of ~30% of the ARC genes in both sexes the transcriptomic effects are 3× more severe in males than their female counterparts, as indicated by the Weighted Pathway Regulation measure. Both treatments significantly restored the ARC neurotransmission transcriptome to the non-IS condition with PMX53 performing slightly better, as measured by the Pathway Restoration Efficiency, suggesting these treatments may reduce autistic traits often associated with IS.

Comparison of efficacy of adrenocorticotrophic hormone and methylprednisolone on rat models of infantile spasm

Objective To compare the efficacy of adrenocorticotrophic hormone(ACTH) and methylprednisolone on the rat models of infantile spasms(IS). Methods The SD rats on postnatal 10 day (P10) were divided into blank group (n=18), control group (n=18) and model group (n=110) according to the random number table method.The rats of model group were prepared by adopting prenatal stress exposure and N- methyl -D aspartate (NMDA) injection.In the model group, after inducing epileptic seizures, the rats were divided into different groups (18 rats in each group) according to the random number table method as following: model group Ⅰ (subcutaneous injection of ACTH, 50 IU/kg, at P10: 1400, 2100; P11, P12: 700, 1400, 2100; P13: 700), model group Ⅱ(subcutaneous injection of 9 g/L saline), model group Ⅲ (intraperitoneal injection of methylprednisolone, 60 mg/kg, at P11, P12, P13: 900, once per day), model group Ⅳ (intraperitoneal injection of 9 g/L saline) and model group Ⅴ (positive control group, with no drug or saline injection). Three days later, epilepsy was induced again, and the rats of model group were intraperitoneally injected with NMDA (12 mg/kg) at P13(1000). The rats of control group were injected intraperitoneally with same volume of 9 g/L saline, but the rats of blank group were not treated.Behaviors of rats with epilepsy seizures were observed and epilepsy scores were given.The expression of corticotropin-releasing hormone (CRH) in the hypothalamus of each group was detected by using immunohistochemistry and fluorescence quantitative polymerase chain reaction.The learning and memorizing capacity of the rats were measured by Y-maze experiment. Results There was no death in the model group after the onset of seizure.In the model group Ⅰ, 13 cases were attacked(72.22%), and 14 cases were attacked in the model group Ⅲ(78.78%). The level of attack was decreased.The buckling state was not observed in model group and Ⅲ, but the latency period of epilepsy was prolonged and the epilepsy scores were significantly decreased.There were no significant differences of onset latency [(2 369.38±628.70) s vs.(1 922.93±462.36) s] and epilepsy score[(2.15±1.14) scores vs.(2.07±0.83) scores] between the 2 groups (all P>0.005). The rats of model group Ⅱ, Ⅳ, Ⅴ were all attacked completely and presented buckling state.There was no onset or death in blank group and control group.The number of CRH positive cells and CRH mRNA relative expression of each model group were higher than those in the blank group and control group.The number of CRH positive cells and CRH mRNA expression of model group Ⅰ and Ⅲ were lower than those in model group Ⅱ, Ⅳ and Ⅴ, and the differences were significant (all P 0.002 4). No significant difference was found between blank group and control group, or among model group Ⅱ, Ⅳ and Ⅴ (all P>0.002 4). There were no significant differences in the learning capacity among all groups (F=2.196, P>0.002 4). The correct response rate after 24 hours of the model group was lower than the blank group and control group, and ACTH and methylprednisolone pretreatment did not influence the memorizing capacity (P>0.002 4). Conclusion The effect of pretreatment of ACTH is similar to that of methylprednisolone in the rat model of IS. Key words: Infantile spasm; Adrenocorticotrophic hormone; Methylprednisolone; Rats model; Corticotropin-releasing hormone

Preclinical Screening for Treatments for Infantile Spasms in the Multiple Hit Rat Model of Infantile Spasms: An Update.

Infantile spasms are the typical seizures of West syndrome, an infantile epileptic encephalopathy with poor outcomes. There is an increasing need to identify more effective and better tolerated treatments for infantile spasms. We have optimized the rat model of infantile spasms due to structural etiology, the multiple-hit rat model, for therapy discovery. Here, we test three compounds administered after spasms induction in the multiple hit model for efficacy and tolerability. Specifically, postnatal day 3 (PN3) male Sprague-Dawley rats were induced by right intracerebral injections of doxorubicin and lipopolysaccharide. On PN5 p-chlorophenylalanine was given intraperitoneally (i.p.). Daily monitoring of weights and developmental milestones was done and rats were intermittently video monitored. A blinded, randomized, vehicle-controlled study design was followed. The caspase 1 inhibitor VX-765 (50-200mg/kg i.p.) and the GABAB receptor inhibitor CGP35348 (12.5-100mg/kg i.p.) each was administered in different cohorts as single intraperitoneal injections on PN4, using a dose- and time-response design with intermittent monitoring till PN5. 17β-estradiol (40ng/g/day subcutaneously) was given daily between PN3-10 and intermittent monitoring was done till PN12. None of the treatments demonstrated acute or delayed effects on spasms, yet all were well tolerated. We discuss the implications for therapy discovery and challenges of replication trials.

Estradiol does not affect spasms in the betamethasone-NMDA rat model of infantile spasms.

This study attempted to validate the effects of neonatal estradiol in ameliorating the spasms in the prenatally betamethasone-primed N-methyl-d-aspartate (NMDA) model of infantile spasms in rats as shown previously in a mouse Arx gene knock-in expansion model of infantile spasms. Neonatal rats prenatally exposed to betamethasone (on day 15 of pregnancy) were treated with subcutaneous 40 ng/g estradiol benzoate (EB) between postnatal days (P)3-P10 or P0-P5. A synthetic estrogen analogue, diethylstilbestrol, was used between P0 and P5 (2 μg per rat, s.c.). On P12, P13, and P15, the rats were subjected to NMDA-triggered spasms, and latency to onset and number of spasms were evaluated. Rats with EB on P3-P10 were tested after spasms in the open field, novel object recognition, and elevated plus maze to determine effects of treatment on behavior. Additional rats with P3-P10 or P0-P5 EB were investigated for γ-aminobutyric acid (GABA)ergic neurons (glutamate decarboxylase [GAD]67 expression) in the neocortex. As a positive control, a group of rats received either subcutaneous adrenocorticotropic hormone (ACTH) (2 × 0.3 mg/kg on P12 and 3 × 0.3 mg/kg on P13 and P14) or vehicle after the first episode of spasms on P12. Neither EB treatment nor diethylstilbestrol consistently affected expression of spasms in this model, although we found a significant increase in GAD67-immunopositive cells in the neocortex after P3-P10 and P0-P5 EB treatment, consistent with a study in mice. Behavioral tests showed increase in lateralization in male rats treated with P3-P10 EB, a behavioral trait usually associated with female sex. Diethylstilbestrol treatment in male rats resulted in arrested pubertal descent of testes. ACTH had robust effects in suppressing spasms. Treatment of infantile spasms (IS) using neonatal EB may be justified in those cases of IS that present with detectable deficits in GABAergic neurons. In other types of IS, the efficacy of neonatal EB and its analogues is not supported.

Efficacy and tolerability of the galanin analog NAX 5055 in the multiple-hit rat model of symptomatic infantile spasms

Infantile spasms are seizures manifesting in infantile epileptic encephalopathies that are associated with poor epilepsy and cognitive outcomes. The current therapies are not always effective or are associated with serious side effects. Early cessation of spasms has been proposed to improve long-term outcomes. To identify new therapies for infantile spasms with rapid suppression of spasms, we are using the multiple-hit rat model of infantile spasms, which is a model of refractory infantile spasms. Here, we are testing the efficacy and tolerability of a single dose of the galanin receptor 1 preferring analog, NAX 5055, in the multiple-hit model of spasms. To induce the model, postnatal day 3 (PN3) male Sprague-Dawley rats underwent right intracerebral infusions of doxorubicin and lipopolysaccharide; p-chlorophenylalanine was then injected intraperitoneally (i.p.) at PN5. After the onset of spasms at PN4, 11-14 rats/group were injected i.p. with either NAX 5055 (0.5, 1, 2, or 4mg/kg) or vehicle. Video monitoring for spasms included a 1h pre-injection period, followed by 5h of recording post-injection, and two 2h sessions on PN5. The study was conducted in a randomized, blinded manner. Neurodevelopmental reflexes were assessed daily as well as at 2h after injection. Respiratory function, heart rate, pulse distension, oximetry and blood glucose were measured 4h after injection. The relative expression of GalR1 and GalR2 mRNA over β-actin in the cerebral cortex and hippocampus was determined with real time reverse transcription polymerase chain reaction. There was no acute effect of NAX 5055 on spasm frequency after the single dose of NAX 5055 (n=11-13 rats/group, following exclusions). Neurodevelopmental reflexes, vital signs, blood glucose measured 4h post-injection, and survival were not affected. A reduction in pulse and breath distention of unclear clinical significance was observed with the 7mg/kg NAX 5055 dose. GalR1 mRNA was present in the cerebral cortex and hippocampus of PN4 and adult rats. The hippocampal - but not the cortical - GalR1 mRNA expression was significantly lower in PN4 pups than in adults. GalR1 mRNA was also at least 20 times less abundant in the PN4 cortex than GalR2 mRNA. In conclusion, a single dose of NAX 5055 has no acute efficacy on spasms or toxicity in the multiple hit rat model of medically refractory infantile spasms. Our findings cannot exclude the possibility that repetitive NAX 5055 administration may show efficacy on spasms. The higher expression of GalR2 in the PN4 cortex suggests that GalR2-preferring analogs may be of interest to test for efficacy on spasms.

CPP‐115, a vigabatrin analogue, decreases spasms in the multiple‐hit rat model of infantile spasms

Infantile spasms (IS) have poor outcomes and limited treatment options, including vigabatrin, a γ-aminobutyric acid (GABA) aminotransferase inactivator. Vigabatrin has been associated with retinal toxicity. A high affinity vigabatrin analogue (CPP-115; Catalyst Pharmaceutical Partners, Inc., Coral Gables, FL, U.S.A.) has shown lower risk of retinal toxicity. Here, we test the efficacy of CPP-115 in reducing spasms and its tolerability in the multiple-hit rat model of IS, in which daily vigabatrin reduced spasms for only one day, but was not well tolerated. Male rats were treated with the protocol of the multiple-hit model of IS on postnatal day 3 (PN3). Using a randomized, blinded, vehicle-controlled, dose-response study design, CPP-115 (0.1, 1, or 5 mg/kg intraperitoneally [i.p.]) or vehicle was given daily (PN4-12) or as a single injection (PN7) after spasm onset. Intermittent video- or video-electroencephalography (EEG) monitoring was done. Secondary end points included the following: daily weights, survival, performance on open field activity, surface righting time, and negative geotaxis (PN3-20), horizontal bar (PN13-20), and Barnes maze (PN16-19). Statistics used a linear mixed model of raw or normalized log-transformed data, taking into account the repeated observations on each animal. The lower CPP-115 doses (0.1-1 mg/kg/day, PN4-12) reduced spasms between PN6 and 7 without increasing mortality. CPP-115 at 5 mg/kg/day (PN4-12) reduced spasms earlier (PN5), but was eventually lethal. A single CPP-115 injection (1 mg/kg, i.p.) decreased electroclinical spasms acutely but transiently. CPP-115 transiently improved the probability to >50% reduction of spasms, but did not accelerate spasm cessation. CPP-115 did not alter neurodevelopmental outcomes or visuospatial learning. We provide proof-of-concept evidence that CPP-115, a vigabatrin analogue, decreases spasms in the multiple-hit rat model of IS at considerably lower and better tolerated doses than vigabatrin did in our previous studies. Further optimization of the treatment protocol is needed. CPP-115 may be a promising new candidate treatment for IS with better tolerability than vigabatrin.