Differential vulnerability of substantia nigra and corpus striatum to oxidative insult induced by reduced dietary levels of essential fatty acids.
Study Goal
The researchers aimed to determine whether oxidative stress contributes to the reduction of dopaminergic neurons in the substantia nigra due to essential fatty acid (EFA) dietary restriction, and to assess the redox balance in brain regions under this condition.
Results Summary
The study found that EFA dietary restriction reduced docosahexaenoic acid (DHA) levels and increased lipid peroxidation in the substantia nigra, while the corpus striatum showed resilience with increased superoxide dismutase activity. The effects varied between generations, with more pronounced neuronal degeneration and oxidative stress in the second generation.
Population
Wistar rats raised from conception on controlled or experimental diets with varying levels of linoleic and α-linolenic fatty acids.
Effective Dosage
Not specified (dietary levels of linoleic and α-linolenic fatty acids were adjusted but exact amounts not provided).
Duration
One (F1) or two (F2) generations.
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
two-generation EFA dietary restriction | decrease | number and size of dopaminergic neurons in the substantia nigra rostro-dorso-medial | rat brains | - | reduced | #1 |
experimental diet containing reduced levels of linoleic and α-linolenic fatty acids | decrease | docosahexaenoic acid (DHA) levels of SN phospholipids | F1 group | ~28% | significantly reduced | #2 |
experimental diet containing reduced levels of linoleic and α-linolenic fatty acids | decrease | docosahexaenoic acid (DHA) levels of SN phospholipids | F2 group | ~50% | significantly reduced | #3 |
experimental diet containing reduced levels of linoleic and α-linolenic fatty acids | no change | lipid peroxidation (LP) | F1 adult animals of the experimental group | - | there was no | #4 |
experimental diet containing reduced levels of linoleic and α-linolenic fatty acids | increase | total superoxide dismutase (t-SOD) activity | F1 adult animals of the experimental group | p < 0.01 | significant increase | #5 |
experimental diet containing reduced levels of linoleic and α-linolenic fatty acids | decrease | dopaminergic and non-dopaminergic neurons | EF2 young animals | - | degeneration | #6 |
experimental diet containing reduced levels of linoleic and α-linolenic fatty acids | increase | lipid peroxidation (LP) | EF2 young animals | p < 0.01 | significant increase | #7 |
experimental diet containing reduced levels of linoleic and α-linolenic fatty acids | decrease | catalase (CAT) activity | EF2 young animals | p < 0.001 | decrease | #8 |
experimental diet containing reduced levels of linoleic and α-linolenic fatty acids | no change | lipid peroxidation (LP) and catalase (CAT) activity | EF2 young animals | - | no inter-group difference was found | #9 |
experimental diet containing reduced levels of linoleic and α-linolenic fatty acids | increase | total superoxide dismutase (t-SOD) activity | EF2 young animals | p < 0.05 | significant increase | #10 |
unbalanced EFA dietary levels | decrease | redox balance in the substantia nigra | - | - | reduce | #11 |
Oxidative stress (OS) has been implicated in the etiology of certain neurodegenerative disorders. Some of these disorders have been associated with unbalanced levels of essential fatty acids (EFA). The response of certain brain regions to OS, however, is not uniform and a selective vulnerability or resilience can occur. In our previous study on rat brains, we observed that a two-generation EFA dietary restriction reduced the number and size of dopaminergic neurons in the substantia nigra (SN) rostro-dorso-medial. To understand whether OS contributes to this effect, we assessed the status of lipid peroxidation (LP) and anti-oxidant markers in both SN and corpus striatum (CS) of rats submitted to this dietary treatment for one (F1) or two (F2) generations. Wistar rats were raised from conception on control or experimental diets containing adequate or reduced levels of linoleic and α-linolenic fatty acids, respectively. LP was measured using the thiobarbituric acid reaction method (TBARS) and the total superoxide dismutase (t-SOD) and catalase (CAT) enzymatic activities were assessed. The experimental diet significantly reduced the docosahexaenoic acid (DHA) levels of SN phospholipids in the F1 (~28%) and F2 (~50%) groups. In F1 adult animals of the experimental group there was no LP in both SN and CS. Consistently, there was a significant increase in the t-SOD activity (p < 0.01) in both regions. In EF2 young animals, degeneration in dopaminergic and non-dopaminergic neurons and a significant increase in LP (p < 0.01) and decrease in the CAT activity (p < 0.001) were detected in the SN, while no inter-group difference was found for these parameters in the CS. Conversely, a significant increase in t-SOD activity (p < 0.05) was detected in the CS of the experimental group compared to the control. The results show that unbalanced EFA dietary levels reduce the redox balance in the SN and reveal mechanisms of resilience in the CS under this stressful condition.