High glucose-6-phosphate dehydrogenase activity contributes to the structural plasticity of periglomerular cells in the olfactory bulb of adult rats

Glucose-6-phosphate dehydrogenase (G6PD) activity, assayed spectrophotometr ically, was found to be higher in the olfactory bulb (OB) than in other bra in areas of adult rats [P. Ninfali, G. Aluigi, W. Balduini, A. Pompella, Gl ucosed-phosphate dehydrogenase is higher in the olfactory bulb than into ot her brain areas, Brain Res. 744 (1997) 138-142]. Histochemical demonstratio n of G6PD activity in cryostat sections of OB, analyzed with optical micros copy, revealed a marked and well defined line of formazan deposition in the internal part of the glomerular layer (Glm), indicating that G6PD was much higher in cells distributed along the glomeruli. Electron microscope analy sis showed that G6PD activity was mainly concentrated in cytoplasm and dend rites of periglomerular cells, the interneurons which span glomeruli and co nnect olfactory nerves with mitral/tufted cells. Since G6PD regulates the f lux through the hexose monophosphate shunt (HMS) pathway, which provides NA DPH for reductive biosynthesis and pentose phosphates for nucleic acid form ation, it can be concluded that high G6PD activity in periglomerular neuron s is functional to their differentiating capability. This result is consist ent with the occurrence of structural plasticity events in the OB of adult rats. (C) 1999 Elsevier Science B.V. All rights reserved.