BACKGROUND: Diverse injury to central nervous system results in proliferation and hypertrophy of astrocytes. The hallmark of this response is enhanced expression of the major intermediate filament protein of astrocyte, glial fibrillary acidic protein(GFAP). These obsevations suggested that GFAP may be a useful biochemical indicator of neurotoxicity. This study is designed for investigating the chronological effects of the thiamine deficiency on the astrogrial GFAP immunoreactivity in the rat forebrain, and for comparing the difference between time-sequenital morphological changes of luxol fast blue-cresyl violet stain reported in previous study and GFAP immunoreactivity. METHODS: A total of 40 healthy Sprague-Dawley strain rats, weighing about 200gm were used as experimental animals(10 control, 30 thiamine deficient rats). Pyrithiamine was injected intraperitonially for 9 days and thiamine deficient diet was continuously supplied until sacrifice. Thiamine deficient rats were subdivided into 3 groups according to thiamine deficient state. Immunohistochemical stains for GFAP in the regions of thalamus, medial mammillary nucleus and CA1 sector in hippocampus were performed by free floating method in cell culture plate. All preperations were observed with light microscope. RESULTS: GFAP immunoactivities at thalamus were tracely positive(+) in controls, strongly positive(+++) in group I, and moderately positive(++) in group II and III. But GFAP immunoactivities at medial mammillary nucleus were tracely positive( ) in controls, moderately positive(++) in group I and III , and strongly positive(+++) in group II. At the CA1 region of hippocampus, the immunoactivities were weakly positive in controls , strongly positive(+++) in group I and II, and moderately positive(++) in group III. The diverse patterns of GFAP immunoreactivities in each vulnerable site were different from the previous morphological study. In luxol-fast and cresyl violet staining, the neuronal damage and necrosis were marked in group III, group II, and group I, in that order, which findings are consistent in all regions. CONCLUSIONS: Different patterns of time-sequential GFAP immunoactivities at each vulnerable site suggest that there are regional differences in sensitivity and resistance to thiamine deficiency.
Animals ; Astrocytes ; Cell Culture Techniques ; Central Nervous System ; Coloring Agents ; Diet ; Glial Fibrillary Acidic Protein* ; Hippocampus ; Hypertrophy ; Intermediate Filaments ; Necrosis ; Neurons ; Prosencephalon* ; Pyrithiamine ; Rats* ; Rats, Sprague-Dawley ; Thalamus ; Thiamine Deficiency* ; Thiamine* ; Viola

OBJECTIVE: This study was designed for developing a new experimental animal model of Wernicke's encephalopathy, and for investigating the timesequential morphological changes in the thiamine deficient rat brain by thiamine deficient diet with short term treatment of pyrithiamine. METHODS: A total of 40 healthy Sprague-Dawley strain rats, weighing about 2OOgm were used as experimental animals, divided into 10 control rats and 30 thiamine deficient experimental rats. Pyrithiamine (50mg/lOOgm/day) was injected intraperitonially for 9 days and thiamine deficient diet (20gm/rat/day) was continuously supplied until sacrifice. Then thiamine deficient experimental rats were subdivided into 3 groups according'to the exposure time of thiamine deficiency. For observing the morphological features in thalamus, medial mammillary nucleus and CA, sector in hippocampus, luxol-fast blue-cresy violet stain was performed. RESULTS: Treatment with pyrithiamine and thiamine deficient diet results in weight loss and decrement of body temperature on the 12th-14th day, followed by various neurologic manifestations, such as ataxia, hypotonia, circling movement, opisthotonus and loss of righting reflex, on the 16th-20th day, and then died on the 23th-25th, day. Chromatolysis and nuclear condensation of neurons in thalamus, medial mammillary nucleus and CA1 region of hippocampus are observed in group I. Mild edematous changes with neuronal necrosis in group II, and marked neuronal loss with severe edematous necrosis in group III are noted in same regions. CONCLUSION: These time sequential consistent morphological changes suggest that our experimental method could be used as a new animal model of Wernicke's encephalopathy in studying the sequential changes of thiamine deficient rat brain.
Animals ; Ataxia ; Body Temperature ; Brain ; Diet* ; Hippocampus ; Models, Animal ; Muscle Hypotonia ; Necrosis ; Neurologic Manifestations ; Neurons ; Prosencephalon* ; Pyrithiamine* ; Rats* ; Rats, Sprague-Dawley ; Reflex, Righting ; Thalamus ; Thiamine Deficiency ; Thiamine* ; Viola ; Weight Loss ; Wernicke Encephalopathy

Thiamine deficiency is generally accepted as the primary etiologic factor for the Wernicke encephalopathy in human and for the similar neurologic symptoms in thiamine depleted experimental animals. Although pyrithiariiineinduced thiamine deficiency has been known to produce histopathologic lesions within many nuclei of the rat brain, the pathogenic mechanisms involved have not been clarified. Furthermore, the effect of thiamine deprivation on the nature and anatomic distribution of neurotransmitter changes has not been fully explored. The present studies were undertaken to investigate - morphological changes of the basal nucleus of Meynert and vestibular nucleus in thiamine deficient rats induced by pyrithiamine and thiamine deficient diet. For this purpose immunohistochemical stain for choline acetyltransferase was performed. Fifty healthy Sprague-Dawley strain rats weighing about 150 gm, were divided into 10 control group and 40 thiamine deficient group. Animals in thiamine deficient group were treated with daily intraperitoneal injection of pyrithiamine( 50 ug/lOOgm of BW/dbLy, Sigma Co.) for 9 days and were continuously given thiamine deficient diet until to be sacrificed. Thiamine deficient rats were subdivided into 3 groups according to different stages of neurologic manifestations ; the early group, the beginning stage of anorexia, hypothermia and weight loss without neurologic manifestations(sacrificed day ; 9th-13th day) the intermediate group, the developing stage of gait ataxia and hypotonia(sacrificed day ; 17th-19th day) the late group, the established stage of tremor, convulsion and back arching(sacrificed day ; 23th-26th day). All animals were anesthetized with sodium pentobarbital(40mg/kg, I.p.) and perfused in vivo through the ascending aorta with 10% neutral buffered formalin or 4% paraformaldehyde-0. 1% glutaraldehyde in PBS, and then brains were removed. Luxol-fast blue and cresyl violet stain was performed according to routine paraffin method for observing morphologic changes in basal nucleus of Meynert and vestibular nucleus. In addition immunohistochemical stains in the same regions were performed by free floating method in cell culture plate. All preparations were observed with a light microscope. The results obtained were as follows ; 1. Sequential changes of the neurologic manifestations in thiamine deficient rats were weight loss, hypothermia and ariorexia on the 9th-10th day, followed by gait ataxia and hypotonia on the 13th-15th day, and then tremor, convulsion and back arching on the 22th-26th day. 2. Glial proliferation was noted in the basal nucleus of the early group but not in the vestibular nucleus. Atrophy and pyknosis of neurons in basal nucleus and vestibular nucleus were shown in the intermediate group and marke neuronal loss and edematous tissue necrosis were noted in the late group. 3. Choline acetyltransferase immurforeactivity in the basal nucleus and vestibular nucleus was markedly positive in the early group as well as control group, moderately positive in the intermediate groupand minimally positive in the late group. It is suggested that the extent of neuronal damage in thiamine deficient rats is proportional to the duration of thiamine depletion. And the data presented here may account for: the regional susceptability and reversibility of certain symptoms in thiamine deficient rats.
Animals ; Anorexia ; Aorta ; Atrophy ; Basal Nucleus of Meynert* ; Brain ; Cell Culture Techniques ; Choline O-Acetyltransferase* ; Choline* ; Coloring Agents ; Diet ; Formaldehyde ; Gait Ataxia ; Glutaral ; Humans ; Hypothermia ; Injections, Intraperitoneal ; Muscle Hypotonia ; Necrosis ; Neurologic Manifestations ; Neurons ; Neurotransmitter Agents ; Paraffin ; Pyrithiamine ; Rats* ; Rats, Sprague-Dawley ; Seizures ; Sodium ; Thiamine Deficiency ; Thiamine* ; Tremor ; Viola ; Weight Loss ; Wernicke Encephalopathy