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Updated: Apr 18, 2026
Functional Neuroimaging Using Ultrasonic Blood-brain Barrier Disruption and Manganese-enhanced MRI
Published on: July 12, 2012
Ultrastructural Changes of Caudate Nucleus in Mice Chronically Treated with Manganese
Virginia Villalobos1, Juan Pablo Hernández-Fonseca, Ernesto Bonilla
1Departamento de Biología, Facultad Experimental de Ciencias, Universidad del Zulia , Maracaibo , Venezuela .
Abstract:
Manganese (Mn) is able to cross the blood-brain barrier and induces functional and structural alterations during the intoxication by this metal. Therefore, the effects of chronic administration of Mn in the caudate nucleus of mice were evaluated by electron microscopy. Male albino mice were injected intraperitoneally with MnCl2 (5 mg/kg/d) 5 d per week during 9 weeks. The control group received only 0.9% of NaCl solution. The caudate nuclei were extracted and subsequently processed to be observed on a conventional transmission electron microscope at 2, 4, 6, and 9 weeks after treatment. A high percentage of vacuolated and swollen mitochondria were found throughout all the analyzed periods. Myelin disarrangement and ultrastructural alterations related to edema were observed increased in Mn-treated mice at week 9. Granular degeneration of myelin at week 9 accompanied with deposition of electron dense granules in the neuropil was also observed. Edema in neuropil and glial cells was detected from week 2 to week 9 accompanied by swollen mitochondria. Neuronal bodies, synaptic terminals, and perivascular cells were found swollen. Decreased electron density in postsynaptic areas and decreased and dispersed synaptic vesicles in presynaptic areas were noted in Mn-treated animals. Some neurons from Mn-treated mice showed cisternae dilation of the Golgi apparatus. These results suggest that Mn-treatment produces structural alterations in the caudate nucleus that could be responsible for some of the neurotoxic effects of this metal.
Insights
Chronic manganese (Mn) exposure in mice caused significant structural damage in the caudate nucleus, including swollen mitochondria and myelin disarrangement. These findings suggest Mn-induced neurotoxicity may stem from these observed cellular alterations.
Area of Science:
- Neuroscience
- Toxicology
- Cell Biology
Background:
- Manganese (Mn) can cross the blood-brain barrier.
- Mn intoxication can lead to functional and structural brain alterations.
Purpose of the Study:
- To evaluate the chronic effects of manganese administration on the caudate nucleus structure in mice using electron microscopy.
Main Methods:
- Male albino mice received intraperitoneal injections of MnCl2 (5 mg/kg/d) or saline (control) for 9 weeks.
- Caudate nuclei were extracted at 2, 4, 6, and 9 weeks for transmission electron microscopy analysis.
Main Results:
- Manganese-treated mice exhibited widespread vacuolated and swollen mitochondria throughout the study.
- Increased myelin disarrangement, edema in neuropil and glial cells, and swollen neuronal bodies were observed, particularly at week 9.
- Ultrastructural changes included decreased electron density in postsynaptic areas, dispersed synaptic vesicles, and Golgi apparatus dilation.
Conclusions:
- Chronic manganese exposure induces significant structural damage in the mouse caudate nucleus.
- Observed alterations, including mitochondrial swelling and myelin damage, may underlie manganese-induced neurotoxicity.
