Jean Rossier (1944–2026),A pioneer of neuropharmacology, single-cell biology and protein chemistry who helped define modern neuroscience

and affective processes.His 1977 Science paper demonstrating the co-synthesis and co-release of adrenocorticotropic hormone (ACTH) and -endorphin became a landmark of the field, accumulating more than 1,700 citations and helping to establish the principle that neuropeptides could be copackaged and co-regulated with classical hormones.Returning to France in 1980, Rossier founded a neuropharmacology laboratory at the CNRS unit in Gif-sur-Yvette, directed by Robert Naquet.There he shifted his focus to GABA receptors, the major inhibitory neurotransmitter system of the brain.He discovered that -carbolines, negative allosteric modulators of the GABA receptor, could enhance learning and memory, an insight later pursued by pharmaceutical companies in the search for cognitive-enhancing drugs for neurodegenerative and genetic disorders.In 1991, his group achieved a conceptual and technical breakthrough by combining patch-clamp electrophysiology with single-cell RT-PCR.By correlating the electrical properties of individual neurons with the ion channels and receptors whose mRNAs they expressed, Rossier provided the first direct demonstration that molecular and functional identities could be unified at the level of a single cell.This innovation opened the door to single-cell genomics.Three years later, at the request of the Nobel prize Pierre-Gilles de Gennes, Rossier founded the biology teaching and research department at ESPCI Paris.There, he expanded single-cell RT-PCR to analyse the diversity of cortical interneurons.He demonstrated that distinct interneuron types could be defined only through the integration of multiple molecular, morphological and physiological parameters, a framework that has since become standard.His subsequent work revealed that these interneuron populations play specialized roles in neural circuits and in regulating local cerebral blood flow.At ESPCI he also pursued microfluidics and DNA-chip technologies, filing patents and launching a startup devoted to these innovations.enous morphine-like molecules fundamental to pain, reward In memory of Jean Rossier.