The effects of ageing and a vitamin E-deficient diet on the lipopigment content of rat hippocampal and Purkinje neurones

Morphometric investigations of the mitochondrial damage in ceroid lipopigment accumulation due to vitamin E deficiency

Numeric (Nv) and volume (Vv) densities, as well as the average size (skeleton: Sk) of synaptic mitochondria from adult, normally fed and adult, vitamin E deficient animals (11 months of age) were semiautomatically measured by computer-assisted morphometry in the cerebellar granular layer. Nv, Vv and the average mitochondrial volume (V) were measured on perikaryal Purkinje cell organelles preferentially stained for succinic dehydrogenase (SDH) activity. Adult vitamin E deficient animals showed a significant decrease of Nv, a significant increase of Sk and an unchanged value of Vv. While in adult normally fed animals the mitochondria of increased size (Sk>5 microm) were 5.3%, in the adult vitamin E deficient rats this fraction accounted for 25.5%. In Purkinje cell perikarya, vitamin E deficiency resulted in a significant decrease of Vv, Nv and V, as well as a steeper reduction of the percentage of SDH-positive mitochondria of larger size. Taken together, these findings document that vitamin E deficiency is responsible of mitochondrial morphometric alterations in adult rats. Structurally deteriorated mitochondria are reported to play a role in producing increased amounts of free radicals, which can facilitate the accumulation of ceroid pigment.

Reduced intraneuronal lipofuscin content in dementia with Lewy bodies compared with Alzheimer's disease and controls

Lipofuscin has been of interest in dementia of Alzheimer's type (DAT), because of the hypothesis that dementia is a kind of premature ageing. The results of studies on intraneuronal lipofuscin content in DAT are inconsistent. At present no data on intraneuronal lipofuscin in dementia with Lewy bodies (DLB) are available. The amount of lipofuscin in the neurons of the inferior olivary nucleus of 10 brains of DLB patients, 10 of age-matched DAT patients, and 10 of age-matched controls has been measured microfluorometrically. The intraneuronal lipofuscin content in the DLB patients was significantly lower than in the DAT patients and controls. This finding may indicate a general alteration of neuronal cell metabolism in DLB, e.g. a defect of mitochondrial DNA, not confined to neurons developing Lewy bodies.

Effects of chronic chlorpromazine or lithium administration on ageing-related lipopigment in rat Purkinje neurones

Ageing-related accumulation of neuronal lipopigment is considered to be debris from processes of renewal of cellular constituents, but can also reflect cell damage and certain diseases. Chlorpromazine (an example of a class of drug chronically administered in psychiatric practice) has been reported to reduce neuronal lipopigment accumulation, and the present study investigated the effects of 28 weeks of chlorpromazine administration on lipopigment in rat Purkinje neurones. The effects of 26 weeks of lithium administration (also chronically administered in psychiatric practice) were also studied. Lipopigment was identified by fluorescence microscopy and the area enclosed by an outline of each discrete region of lipopigment was measured. While lithium administration was not associated with significant changes in lipopigment variables, chlorpromazine administration was associated with a significant (p=0.001) reduction in the number of discrete lipopigment regions and with significant (p=0.001) differences in the numbers of discrete lipopigment regions in various size categories. The findings are similar to those associated with the administration of acetyl-L-carnitine (which has been reported to reduce some morphological and behavioural associations of brain ageing) and are compatible with a reduction in the rate of lipopigment formation. This could reflect an adverse effect of chlorpromazine administration (i.e. reduced functional activity of neurones) or a beneficial effect (i.e. a reduction in ageing-related changes).

The morphology of lipopigment in rat Purkinje neurons after chronic acetyl-L-carnitine administration: a reduction in aging-related changes

The aging-related accumulation of neuronal lipopigment is considered to be cellular debris from processes of renewal of cellular constituents, but it can also reflect cell damage and certain diseases. Acetyl-L-carnitine (AC) has been reported to reduce some morphological and behavioral associations of brain aging and the present study investigated the effects of 37 weeks of AC administration on lipopigment in rat Purkinje neurons. Lipopigment was identified by fluorescence microscopy and the area enclosed by an outline of each discrete region of lipopigment was measured. Acetyl-L-carnitine was associated with a significant (p = 0.05) reduction in the number of discrete lipopigment regions and there was a significant (p = 0.001) association of AC administration with numbers of lipopigment regions in various size categories. As AC administration was associated with a reduction in some of the aging-related morphological changes in lipopigment, this compound is a candidate for evaluation as a long-term prophylactic agent for the adverse effects of cerebral aging.