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Postnatal expression of glucose-6-phosphate dehydrogenase in different brain areas
P Ninfali1, G Aluigi, A Pompella
1Istituto di Chimica Biologica, Università di Urbino, Italy. p.ninfali@bib.uniurb.it
Insights
Glucose-6-phosphate dehydrogenase (G6PD) activity significantly increases in the rat olfactory bulb during development, alongside other antioxidant enzymes. This suggests enhanced cellular protection in the olfactory bulb during maturation.
Area of Science:
- Neuroscience
- Biochemistry
- Developmental Biology
Background:
- Glucose-6-phosphate dehydrogenase (G6PD) is a key enzyme in the pentose phosphate pathway, crucial for cellular redox balance.
- Brain development involves dynamic changes in enzymatic activity, particularly related to oxidative stress management.
- The olfactory bulb (OB) has unique cellular characteristics, including rapidly renewing periglomerular cells, potentially requiring specific antioxidant defenses.
Purpose of the Study:
- To investigate the developmental pattern of G6PD activity in five distinct rat brain areas: olfactory bulb (OB), cortex, hippocampus, striatum, and septum.
- To compare G6PD activity with other key antioxidant enzymes, including 6-phosphogluconate dehydrogenase (6PGD), glutathione reductase (GR), glutathione peroxidase (GPX), catalase (CAT), and superoxide dismutase (SOD).
- To explore potential synergistic interactions among these enzymes during postnatal development and their role in cellular defense mechanisms.
Main Methods:
- Enzyme activity assays were performed on tissue homogenates from the five brain regions of rats aged 5, 10, 30, 60, and 90 days.
- Electrophoretic analysis was used to examine G6PD isoenzyme patterns.
- Histochemical staining was employed to localize G6PD activity within specific brain regions.
Main Results:
- G6PD activity showed a significant, more than 2-fold increase in the OB from 5 to 90 days, remaining consistently higher than in other brain areas.
- In contrast, G6PD activity was relatively constant in the cortex, hippocampus, striatum, and septum throughout development.
- A coordinated increase in 6PGD, GPX, and GR activities was observed in the OB, correlating with G6PD upregulation, while CAT and SOD exhibited different developmental patterns.
Conclusions:
- G6PD activity significantly increases in the developing rat olfactory bulb, suggesting a specialized role in this brain region.
- The coordinated activation of 6PGD, GPX, and GR alongside G6PD points to an enhanced antioxidant defense system in the OB during development.
- This heightened antioxidant capacity is likely crucial for protecting periglomerular cells, which undergo rapid renewal and are susceptible to oxidative stress.
Abstract:
The activity of glucose-6-phosphate dehydrogenase (G6PD) was studied in five brain areas of rats aged 5 to 90 days. The areas studied were: the olfactory bulb (OB), cortex, hippocampus, striatum and septum. The G6PD activity increased more than 2-fold from 5 to 90 days in the OB, while it was almost constant in the other areas. At every stage of development, the G6PD activity was significantly higher in the OB than in the other areas. The G6PD pattern was compared with 6-phosphogluconate dehydrogenase (6PGD), glutathione reductase (GR); glutathione peroxidase (GPX), catalase (CAT) and superoxide dismutase (SOD) in order to find synergistic interactions among activities of these enzymes during development. Over the considered period, the activity of 6PGD increased significantly in the OB, while no significant difference in activity was detected in the other areas. GR increased significantly and progressively at each developmental stage in all areas. GPX showed a progressive increase in the OB, while in other areas a significant increase was detected at 90 days only. CAT and SOD showed a different and independent pattern which differed from the G6PD pattern. CAT showed the highest level of activity at 5 days then progressively decreased or was constant until 90 days; SOD had the highest value at 5 days, than it decreased at 10 days and increased from 10 to 90 days. In all areas, G6PD activity showed three electrophoretic bands, whose relative activity changed with development. At histochemical level, we found a marked G6PD activity in the periglomerular zone of the OB, which increased with age, while other areas showed a homogeneous staining. The present results demonstrate that G6PD activity increases in the OB during the developmental stages and there is a coordinated simultaneous activation of 6PGD, GPX and GR. It is likely that this enzyme induction increases the antioxidant defense of periglomerular cells that are subject to a rapid renewal and thus much more exposed to oxidant stress.