Richard Amedzrovi Agbesi’s PhD thesis defense will take place on Friday, January 19th at 2:00 PM in the Pierre Gilles de Gennes Amphitheater.This thesis, supervised by Nicolas Chevalier and Vincent Fleury, focuses on the Fundamentals of intestinal peristalsis: myogenic, neurogenic, and hydrodynamic behavior. There will be a cocktail session on the 6th floor where some Ghanaian delicacies will be served.

The thesis aimed to explore the impact of mechanical forces, such as circumferential stretch and hydrostatic pressure, on the contractility of the Enteric Nervous System and smooth muscle from tissue to organ levels. The focus of the thesis included understanding the channels involved in mediating the enteric nervous system and smooth muscle contractility, the diverse roles of various wave patterns, and the resultant hydrodynamics facilitating these functions. A specialized cantilever system was devised to quantify the stretch-tension relationship of a smooth muscle ring. Notably, this setup revealed the mechanosensitive nature of the smooth muscle ring, contracting responsively to circumferential stretch. Subsequently, pharmacological drugs known for blocking specific channels were used to investigate the pathways underlying this mechanosensitive behavior.
Examining the enteric nervous system, both spontaneous and pinch-induced calcium activity were observed. Utilizing a transgenic line expressing the GCamp6f reporter in neural crest cell derivatives, the spontaneous calcium activity in embryonic mice was studied. Pinching the enteric nervous system using a fine Pasteur pipette triggered a calcium flash. Certain channels crucial for spontaneous activity were identified, and the ’plasticity’ of the mechanosensitive response of the ENS was explored using pharmacological drugs. To assess how pressure gradients influence smooth muscle contractility at the organ level, an in-house hydrostatic pressure model was implemented. Experimental and numerical models were then employed to investigate the role of different gut wave patterns and the associated hydrodynamics in modulating smooth muscle contractility.