Pinealectomy causes hippocampal CA1 and CA3 cell loss: reversal by melatonin supplementation.
This experiment determined if the loss of endogenous melatonin via pinealectomy affected rat CA1 and CA3 pyramidal neuron numbers over a 20-month span. Since pinealectomy eliminates many neurohormones, some rats received daily melatonin supplementation to determine if this would reverse its effects. CA1 pyramidal cells were significantly reduced between 2 and 4 months after pinealectomy. CA3 loss was evident at 2 months post-pinealectomy. Melatonin replacement in the drinking water prevented these effects and seemingly promoted the genesis of CA1 cells. Analyses of hippocampal thiobarbituric acid reactive substances (TBARS) levels at 3 and 20 months post-surgery, revealed no significant group differences in lipid peroxidation. However, hippocampal TBARS were higher at 20 than at 3 months in all groups. Pinealectomized rats exhibited a significantly higher ratio of reduced to oxidized glutathione at 3 months but not 20 months, when compared to the sham and melatonin-supplemented rats. This suggests that pinealectomy caused oxidative stress and a subsequent compensatory change in the glutathione system. These results indicate that endogenous melatonin is neuroprotective.
De Butte
M
M
Institute of Neuroscience, Carleton University, Ottawa, Ont., Canada K1S 5B6.
Pappas
B A
BA
D000284:Administration, Oral; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005609:Free Radicals / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects; D015227:Lipid Peroxidation / Q000502:physiology*; D008297:Male; D008550:Melatonin / Q000008:administration & dosage*; D010870:Pineal Gland / Q000378:metabolism* / Q000601:surgery*; D017966:Pyramidal Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D005609:Free Radicals; D005978:Glutathione; D008550:Melatonin