Housing environment bilaterally alters transcriptomic profile in the rat hippocampal CA1 region

by Azusa Kubota, Kentaro Kojima, Shinnosuke Koketsu, Takayuki Kannon, Takehiro Sato, Kazuyoshi Hosomichi, Yoshiaki Shinohara, Atsushi Tajima

Brain asymmetry is a fundamental feature of neural organization. However, the molecular basis of hippocampal lateralization in response to environmental stimuli remains poorly understood. Here, we examined the transcriptomic profiles of the left and right hippocampal CA1 regions in rats reared under isolated or enriched housing conditions to elucidate hemisphere-specific responses and shared molecular adaptations. RNA-sequencing analysis revealed lateralized differences in the number and identity of differentially expressed genes, accompanied by distinct biological themes, as indicated by overrepresentation and gene set enrichment analysis. The left CA1 region was prominently engaged in pathways related to synaptic organization and mitochondrial function, whereas the right CA1 region exhibited enrichment in transcriptional regulation and RNA metabolic processes. Despite these asymmetries, co-expression and protein–protein interaction network analyses revealed shared molecular architectures. Immediate early genes formed consistent central hubs across both hemispheres, and a common Mecp2–Grin2b–Cdkl5–Tet3 protein interaction cluster was identified as a potential integrative regulatory module. Additional enrichment analysis of differentially expressed genes shared between hemispheres further highlighted conserved responses, particularly in synaptic plasticity and cell–cell communication. Together, these findings demonstrate that the left and right CA1 regions employ distinct yet partially convergent transcriptional programs to adapt to environmental stimuli. This coordinated molecular asymmetry provides novel insights into hippocampal lateralization and its role in experience-dependent brain plasticity.

Prospective, multicentre trial on preoperative biliary drainage by endoscopic ultrasound-guided hepaticogastrostomy for resectable/borderline resectable pancreatic cancer with biliary obstruction: the PROLOGUE study - a study protocol

Introduction

Preoperative biliary drainage (PBD) is often required for patients with pancreatic cancer accompanied by biliary obstruction to ensure the safe administration of neoadjuvant chemotherapy or to manage cholangitis and jaundice. Although endoscopic retrograde cholangiopancreatography (ERCP) is the standard approach for PBD, it carries a significant risk of post-ERCP pancreatitis. Endoscopic ultrasound-guided biliary drainage (EUS-BD), particularly via hepaticogastrostomy (EUS-HGS), offers a promising alternative that avoids papillary manipulation. However, the clinical utility of EUS-BD as primary drainage for PBD remains unclear due to a lack of prospective studies. This multicentre prospective trial aims to evaluate the safety and efficacy of EUS-HGS as primary drainage for PBD in patients with resectable or borderline resectable pancreatic cancer.

Methods and analysis

This multicentre prospective study involves seven institutions in Japan. Eligible patients will undergo EUS-HGS using a 7Fr plastic stent. The primary endpoint is clinical success, defined by improvements in bilirubin or liver enzyme levels within 14 days postprocedure. Secondary endpoints include technical success rate, adverse event incidence, stent patency and surgical outcomes. A total of 30 patients will be enrolled, considering an expected clinical success rate of 90% and a 10% dropout allowance.

Ethics and dissemination

This study has been approved by the National Cancer Center Institutional Review Board (Research No. 2024-084). The results of this study will be reported at an international conference and published in an international peer-reviewed journal.

Trial registration number

UMIN ID: 000055173.