Ultrastructural Changes of Caudate Nucleus in Mice Chronically Treated with Manganese.

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.

Bromocriptine treatment in a murine Parkinson's model: ultrastructural evaluation after dopaminergic deafferentation.

The objective of this article was to identify the effects of bromocriptine on the ultrastructure of the caudate nucleus in rats with a 6-hydroxidopamine (6-OHDA) unilateral lesion of the substantia nigra pars compacta. Eighteen Wistar male rats were stereotactically lesioned with 6-OHDA (n=12), or sham lesioned (n=6). Two days after rotational behavior was tested, and 2 days later, 6 rats were treated with 0.3 mg/Kg bromocriptine orally for a month and 6 rats were kept for the same time without treatment. The neuropile of the sham operated and bromocriptine-treated rats was well preserved contrary to the non-bromocriptine-treated rats. Also, it was found that there was a significant difference in the number of synaptic endings with edema in caudate of bromocriptine-treated rats compared with non-treated rats; however, the size of the synaptic endings were different to those found in the sham lesioned rats. Also, as in the sham lesioned group, the bromocriptines showed more synaptic contacts with dendritic spines contrasting to the non-treated group. The results suggest that bromocriptine possesses antioxidant properties because it decreased the ultrastructural alterations after 6-OHDA lesion.

Análisis ultraestructural comparativo en pacientes con enfermedad de Parkinson y ratas viejas / Ultraestructural comparative analysis between Parkinson disease patients and aged rats

Los pacientes con enfermedad de Parkinson idiopático presentan pérdida neuronal de la sustancia negra parte compacta y la consecuente degeneración de la vía nigroestriatal; por otro lado, se ha reportado que los animales viejos también tienen pérdida de dicha inervación. El objetivo del presente trabajo fue comparar los cambios neurodegenerativos en el neuropilo del núcleo caudado de pacientes parkinsónicos y de animales viejos, con el fin de comparar los cambios que sufre dicho núcleo en los dos procesos degenerativos. En el análisis ultraestructural se utilizaron fragmentos del núcleo caudado de pacientes con enfermedad de Parkinson (n= 4) y de ratas viejas de 36 meses de edad (n= 4), para lo cual se midieron 100 botones presinápticos por caudado y se observó la estructura postsináptica y el número de contactos que establecía el botón con la misma estructura. Los resultados muestran que tanto los pacientes con enfermedad de Parkinson como las ratas viejas presentan un incremento estadisticamente significativo en el tamaño de los botones sinápticos, aumento en el número de contactos axodendríticos y aumento en el número de contactos dobles en comparación con los controles. Los datos indican que los pacientes parkinsónicos presentan alteraciones ultraestructurales similares a las de los animales viejos, alteraciones debidas a la ineficiente inervación dopaminérgica procedente del mesencéfalo, por lo cual se considero que el envejecimiento en animales es un buen modelo para el estudio de la neurodegeneración.

Evaluación comportamental, motora y sensitiva en lesiones esterotáxicas bilaterales seriadas del núcleo caudado

Mediante el uso de la metodología etológica que implica observación y registro sistemático del comportamiento, se hace un estudio de los efectos comportamentales, motores y sensitivos de lesiones electrolíticas bilaterales seriadas, reales y ficticias del Núcleo Caudado. Los animales con lesión real presentan déficit sesorio-motor de consideración el cual sufre un proceso de acomodación inicial con posterior estabilización de la función, fenómeno que se enmarca dentro del concepto de "plasticidad cerebral". Se presentan básicamente asimetrías postulares y alteraciones del tono muscular compatibles con alteraciones de los circuitos reverberantes de los Ganglios Basales. Otro aspecto que resulta interesante es la evidencia de una posible especialización de función entre Caudado derecho e izquierdo al igual que especificidad de funciones para las diversas zonas del Estriado (medial y lateral). Se manifiesta mayor severidad en el deterioro de función motora cuando los animales son sometidos a estímulos sensoriales específicos, por tanto se discute la importancia de las entradas sensoriales en la activación de los Ganglios Basales, para que coordinadamente se manifiesten en la función motora

Ultrastructural alterations in caudate nucleus, cerebral cortex and hippocampus produced by morphine.

1. Chronic morphine administration to rats produced diverse ultrastructural alterations in nerve cells and neuropile of caudate nucleus, cerebral cortex and hippocampus through a short term abstinence period. 2. All areas studied showed increasing damage related to time elapsed between the last morphine injection and animal sacrifice. 3. Intracytoplasmic neuronal membranous organelles mainly suffered severe swelling, membrane disarrangement and eventually cell disruption in all areas studied. 4. Hippocampus was the most affected area throughout the study, followed by caudate nucleus and cerebral cortex, where focal damage was seen. 5. Susceptibility to morphine cytotoxic effect in the three areas studied appears to be unrelated to their opiate receptor density. 6. Mitochondrial alterations produced by morphine could be related to interference of the intracellular energy production system and consequent unrestricted cell membrane permeability to water and solutes.