The baboon in epilepsy research: Revelations and challenges

Sudden Unexpected Death in Epilepsy: Respiratory vs. Cardiac Contributions

Sudden Unexpected Death in Epilepsy (SUDEP) poses a significant risk to life expectancy for individuals with epilepsy. Mechanistic insight, while incomplete, has advanced through clinical observational studies and animal models. Yet we lack preventative therapies, which will depend on understanding SUDEP mechanisms. Recurrent convulsive seizures are the major SUDEP risk factor. Cardiorespiratory dysfunction precedes SUDEP, but whether cardiac arrhythmias are major proximate culprits for SUDEP remains to be determined. Here, we highlight recent data from mouse models and clinical studies that provide increasing support for respiratory depression and decreasing evidence for tachyarrhythmia-induced SUDEP. Further, we review data from genetic and chemoconvulsant mouse models that have enabled a deeper understanding for how seizures initiated in the central nervous system propagate to the autonomic nervous system and drive seizure-induced respiratory depression and subsequent SUDEP, rather than supporting a proximate cardiac arrhythmia cause. Ongoing research will continue to identify predictive SUDEP biomarkers, improve animal models, and translate basic research into precision medicine approaches. Identifying and understanding the brainstem circuits vulnerable in seizure-induced apnea will enable therapeutic interventions, to enhance the quality of life and life expectancy for individuals with epilepsy.

Neutrophil to lymphocyte ratio in captive olive baboons (Papio anubis): The effects of age, sex, rearing, stress, and pregnancy

In apes and humans, neutrophil to lymphocyte ratio (NLR) can be used as a predictive indicator of a variety of clinical conditions, longevity, and physiological stress. In chimpanzees specifically, NLR systematically varies with age, rearing, sex, and premature death, indicating that NLR may be a useful diagnostic tool in assessing primate health. To date, just one very recent study has investigated NLR in old world monkeys and found lower NLR in males and nursery-reared individuals, as well as a negative relationship between NLR and disease outcomes. Given that baboons are increasingly used as research models, we aimed to characterize NLR in baboons by providing descriptive data and examinations of baboon NLR heritability, and of the relationships between NLR, age, rearing, and sex in 387 olive baboons (Papio anubis) between 6 months and 19 years of age. We found that (1) mother-reared baboons had higher NLRs than nursery-reared baboons; (2) females had higher NLRs than males; and (3) there was a quadratic relationship between NLR and age, such that middle-aged individuals had the highest NLR values. We also examined NLR as a function of transport to a new facility using a subset of the data. Baboons exhibited significantly higher transport NLRs compared to routine exam NLRs. More specifically, adult baboons had higher transport NLRs than routine NLRs, whereas juveniles showed no such difference, suggesting that younger animals may experience transport stress differently than older animals. We also found that transport NLR was heritable, whereas routine NLR was not, possibly suggesting that stress responses (as indicated in NLR) have a strong genetic component. Consistent with research in humans and chimpanzees, these findings suggest that NLR varies with important biological and life history variables and that NLR may be a useful health biomarker in baboons.

What we have learned from non-human primates as animal models of epilepsy

Non-human primates (NHPs) have played a crucial role in our understanding of epilepsy, given their striking similarities with humans. Through their use, we have gained a deeper understanding of the neurophysiology and pathophysiology of epileptic seizures, and they have proven invaluable allies in developing anti-seizure therapies. This review explores the history of NHPs as natural models of epilepsy, discusses the findings obtained after exposure to various chemoconvulsant drugs and focal electrical stimulation protocols that helped uncover important mechanisms related to epilepsy, examines diverse treatments to prevent and manage epilepsy, and addresses essential ethical issues in research. In this review, we aim to emphasize the important role of NHPs in epilepsy research and summarize the benefits and challenges associated with their use as models.

Genomic evidence for the suitability of Göttingen Minipigs with a rare seizure phenotype as a model for human epilepsy

Epilepsy is a complex genetic disorder that affects about 2% of the global population. Although the frequency and severity of epileptic seizures can be reduced by a range of pharmacological interventions, there are no disease-modifying treatments for epilepsy. The development of new and more effective drugs is hindered by a lack of suitable animal models. Available rodent models may not recapitulate all key aspects of the disease. Spontaneous epileptic convulsions were observed in few Göttingen Minipigs (GMPs), which may provide a valuable alternative animal model for the characterisation of epilepsy-type diseases and for testing new treatments. We have characterised affected GMPs at the genome level and have taken advantage of primary fibroblast cultures to validate the functional impact of fixed genetic variants on the transcriptome level. We found numerous genes connected to calcium metabolism that have not been associated with epilepsy before, such as ADORA2B, CAMK1D, ITPKB, MCOLN2, MYLK, NFATC3, PDGFD, and PHKB. Our results have identified two transcription factor genes, EGR3 and HOXB6, as potential key regulators of CACNA1H, which was previously linked to epilepsy-type disorders in humans. Our findings provide the first set of conclusive results to support the use of affected subsets of GMPs as an alternative and more reliable model system to study human epilepsy. Further neurological and pharmacological validation of the suitability of GMPs as an epilepsy model is therefore warranted.