Biology subjects

Balasuriya, G. K.

Publications and source records attributed to Balasuriya, G. K..

3 recordsLinked to original sources

bioRxiv2025

A Minimally Invasive, Scalable and Reproducible Neonatal Rat Model of Severe Focal Brain Injury

BackgroundNeonatal brain injuries such as stroke cause focal ischemic lesions that often result in lifelong neurological disabilities, as treatment options are limited. To speed up the discovery of potential therapies, early-phase screening with models that reliably reproduce brain injury, with scalable injury volume and minimal confounders, such as varying anaesthesia duration and painful procedures, is essential. MethodsPostnatal day 10 Sprague-Dawley rats of both sexes, with four litters per group and timepoint, were randomly allocated to delivery of intraperitoneal Rose Bengal (25, 40, or 60 mg/kg) and 10 minutes of light-emitting diode illumination through the intact scalp and skull. Infarct progression and reproducibility were assessed at 24 hours, 7 days, and 14 days post-injury. Outcomes included infarct volume and sensorimotor function, and cleaved caspase-3, glial fibrillary acidic protein (GFAP), and ionised calcium-binding adaptor molecule 1 (Iba1) immunoreactivity, with analysis of sex differences. Data were analysed using one-way or two-way ANOVA with Sidaks post-hoc tests. ResultsThere was no mortality due to the infarct, and procedure time was approximately 19 minutes across all groups; the lesion was consistent and supported scalability. The 25 mg/kg dose produced a reproducible cortical infarct (3.74 {+/-} 0.58 mm3; CV = 31%). Lesion size increased with dose and decreased over time (11.15 {+/-} 0.63 mm3 at 60 mg/kg versus 0.05 {+/-} 0.007 mm3 at 14 days; p < 0.0001). Cleaved caspase-3 and glial activation persisted for 14 days, indicating ongoing apoptosis and gliosis. No sex-dependent effects were observed in lesion volume, behaviour, or gliosis. ConclusionsThis refined neonatal photothrombotic ischaemia model is reproducible, scalable, and ethically improved, requiring no skin incision. Its minimal surgical burden, absence of mortality, consistent histopathology, and measurable functional outcomes make it an ideal platform for preclinical screening of neuroprotective and reparative interventions in the developing brain.

developmental biology↗

bioRxiv2022

Caecal dysfunction in the NL3R451C mouse model of autism

The mouse caecum is a pouch-like structure that is anatomically similar to the human appendix and is hypothesised to serve as a reservoir for commensal bacteria. The gastrointestinal tract is also home to the largest immunological organ of the body and the enteric nervous system (ENS), which regulates gut motility and secretion. The caecum is therefore an ideal location to study neuro-immune-microbe interactions in gut-brain communication. Individuals with Autism Spectrum Disorder (ASD; autism) frequently present with gastrointestinal symptoms in addition to core diagnostic behavioural features, implying a gut-brain link. More broadly, changes in gut-brain connectivity are now thought to play a critical role in a range of neurodevelopmental disorders. Here, we employed a mouse model of autism expressing a missense mutation in the neuroligin-3 post-synaptic protein that affects brain and enteric neuronal activity (NL3R451C mice). We previously observed abnormal caecal ENS architecture and immune cell morphology in the caecal patch in this model, however it is unknown if caecal function is altered in NL3R451C mice. Using a tri-cannulation approach to record motility patterns in the mouse caecum, we identified novel caecal motor complexes in ex vivo preparations. Caecal permeability and neurally-evoked secretion levels were also studied. Key immune populations including gut macrophages and dendritic cells within the caecal patch were stained using immunofluorescence to investigate shifts in immune activity. Caecal motility patterns in NL3R451C mice differed from wildtype littermates. Specifically, caecal motor complexes occurred at a higher frequency and for a shorter duration in NL3R451C mice than in wildtype littermates. In NL3R451C mice, neurally-evoked caecal secretion was reduced in response to the nicotinic acetylcholine receptor agonist (DMPP), but permeability was unchanged. Increased numbers of caecal patches were observed in NL3R451C mice compared to wildtype, with no alterations in morphology of selected immune populations. Future research is warranted to better understand caecal function and how neuro-immune interactions in the caecum affect health and influence GI function in neurodevelopmental disorders via the gut-brain axis.

neuroscience↗

bioRxiv2022

Hyperimmune bovine colostrum containing lipopolysaccharide antibodies (Imm124-E) has a non-detrimental effect on gut microbial communities in unchallenged mice.

1Enterotoxigenic Escherichia coli (ETEC) is a leading cause of bacterial diarrhea in travelers, military personnel and children in developing countries. Infection has the potential to cause long-term gastrointestinal dysfunction. Preventative treatments for ETEC-induced diarrhea exist, yet the effects of these treatments on gastrointestinal commensals in healthy individuals is unclear. Whether administration of a prophylactic preventative treatment for ETEC-induced diarrhea causes specific shifts in gut microbial populations in controlled environments is also unknown. Here we studied the effects of a hyperimmune bovine colostrum (IMM-124E) used in the manufacture of Travelan(R) (AUST L 106709) on gastrointestinal bacteria in healthy C57BL/6 mice. Using next generation sequencing, we aimed to test the onset and magnitude of potential changes to the mouse gut microbiome in response to the anti-diarrheagenic hyperimmune bovine colostrum product, rich in immunoglobulins against select ETEC strains (Travelan(R), Immuron Ltd). We engineered changes in mouse fecal and cecal bacterial communities by delivering lipopolysaccharide (LPS) antibodies derived from bovine colostrum via dietary supplementation. Holstein Friesian and Jersey cows between 28- and 35-weeks gestation stimulated by subcutaneous delivery of three important pathogenic and antigenic determinants; LPS, flagella, and colonization factor antigen (CFA), produced a hyperimmune colostrum (IMM-124E) with demonstrated beneficial effects on health via modulation of metabolic pathways and immune function. We show that in mice administered colostrum containing LPS antibodies there was an increased abundance of potentially gut-beneficial bacteria, such as Akkermansia and Desulfovibrio, without disrupting the underlying ecology of the gastrointestinal tract. Compared to controls, there was no difference in overall weight gain, body or cecal weights or small intestine length following LPS antibody colostrum supplementation. Overall, dietary supplementation with colostrum containing LPS antibodies produced subtle alterations in gut bacterial composition of mice. Primarily, Travelan(R) LPS antibody treatment decreased the ratio of Firmicutes/Bacteroidetes in gut microbial populations in unchallenged healthy mice. Further studies are required to examine the effect of Travelan(R) LPS antibody treatment to engineer the microbiome in a diseased state and during recovery.

microbiology↗