[Thiamine deficiency in chronic alcoholism. The effect of thiamine treatment on the erythrocyte transketolase activity and the thiamine pyrophosphate effect].
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We studied at the biochemical, morphological, and behavioral levels the effect of chronic ethanol consumption, associated or not with a mild thiamine deficiency episode. We found that (i) thiamine deficiency induced a significant decrease of the acetylcholinesterase (AChE) activity both in cortex and hippocampus; (ii) chronic ethanol treatment has no effect on cortical AChE activity, but induced a significant decrease of hippocampal enzyme activity; (iii) the reduction in cortical and hippocampal AChE activity induced by chronic ethanol treatment associated with a 1-week thiamine deficiency was also significant and was greater than that induced by ethanol alone. Furthermore, either chronic ethanol or thiamine deficiency induced a significant decrease in the release of acetylcholine (ACh) in the stimulated condition using high potassium concentration; and when both treatments were associated the decrease was even greater. In the unstimulated condition, the reduction in the release of ACh was greater for ethanol treatment than for thiamine deficiency. Open-field tests showed that only in the "sniffing" category were there significant differences among the experimental groups. No morphological change was detected by optical microscopy, suggesting that the injury process was in its initial stages in which only functional and behavioral changes are displayed. In addition, our biochemical results indicate that cortical cholinergic susceptibilities to ethanol and thiamine deficiency are significantly different.
Young male Wistar rats were fed with a thiamine-free diet for 35 days. The growth of the thiamine-deficient animals was considerably suppressed, as compared to a pair-fed control group (body weights: 140.4 +/- 4.3 g v. 243.1 +/- 4.3 g). A weight-matched control group was therefore evaluated in addition. Histological and ultrastructural investigations of the hearts did not reveal any morphological abnormalities. Stereological analysis was performed on left ventricular papillary muscles. One-way analysis of variance showed significant differences of stereological parameters between the three groups which were not associated with significant linear contrasts between the thiamine-deficient group and the weight-matched control group. Thus, the changes are not to be related to direct effects of thiamine depletion on the myocardium. Conclusively, the data indicate that stereological parameters (ratios) of the myocardium depend on heart weight and body weight, respectively, and are changed during normal growth. Our stereological estimates disclosed alterations of the following parameters: numerical density of myocardial cell nuclei, length density and volume density of capillaries, surface density of outer mitochondrial membranes and surface-to-volume ratio of mitochondria, and volume density of myofibrils. Furthermore, relative heart weights decrease in normal growth. It is concluded that our experimental model of chronic alimentary thiamine deficiency was associated with a normal structure of the myocardium. All significant differences between the thiamine-deficient group and the control group are explained by body weight changes following starvation in chronic thiamine deficiency.
Biochemical alterations of serotoninergic parameters have been demonstrated in experimental thiamine deficiency. In addition, hypophagia and hypothermia, two physiological processes associated with changes in the serotonin [5-hydroxytryptamine (5-HT)] system, are manifest early during the progression of thiamine deficiency. The binding of selected 5-HT radioligands was therefore investigated in discrete brain regions of pyrithiamine-induced thiamine-deficient rats. Using quantitative receptor autoradiography, the binding of 8-hydroxy-2-(di-n-[3H]propylamino) tetralin, a ligand used to label the somatodendritic 5-HT1A autoreceptor of the dorsal raphe nucleus, was found to be unaffected in this region, suggesting that the structural integrity of the 5-HT cell bodies is maintained throughout the course of pyrithiamine treatment. Increased binding of [3H]-ketanserin was observed in regions considered vulnerable as well as in some considered to be nonvulnerable during the course of thiamine deficiency. These binding changes, which appear to represent changes in the density of the postsynaptic 5-HT2A receptor population rather than the "tetrabenazine-sensitive" vesicular monoamine transporter, are evident before the appearance of histopathologic lesions and coincide with altered tissue concentrations of 5-HT. These data suggest that 5-HT neurons, although structurally intact, are functionally affected early during the progression of thiamine deficiency. These alterations, which are likely a part of adaptive neuronal change consequent to thiamine dysfunction, may be important in the physiological manifestations and the learning deficits commonly encountered in experimental thiamine deficiency.
We recorded the auditory brainstem responses of rats fed a thiamin-deficient diet. The interpeak latencies between waves I and III, as well as those between waves I and IV, were significantly prolonged from day 24, while the latency of wave I was prolonged on day 26 of the thiamin-deficient diet. These delayed responses were corrected in 2 to 4 days after the initiation of daily intraperitoneal thiamin injections from day 32. The rats that were fed the thiamin-deficient diet, and then sacrificed on day 32, showed a decrease of total thiamin levels in the brain (26% of the level in control rat brains). Based on these results, we emphasize the value of the auditory brainstem response to detect thiamin deficiency.
Treatment of rats with the central thiamine antagonist, pyrithiamine, results in severe neurological symptoms such as ataxia and convulsions. Induction of proto-oncogene c-fos expression, often related to seizure activity, has been detected in the brains of thiamine-deficient rats by means of Northern blot analysis and in situ hybridization. Region-selective increases of lactate observed following thiamine deficiency development are largely coincident with histologically vulnerable regions. When thiamine-deficient rats were treated with the calcium channel blocker, nicardipine, lesions associated with thiamine deficiency did not appear and there was no induction of c-fos mRNA expression. This suggests a neurocytoprotective role of nicardipine to neuronal cell damage in thiamine-deficient encephalopathy.
Male Wistar rats weighing 75 to 85 g and maintained on a thiamine deficient diet for 33 days showed growth inhibition with the principal manifestation of significant weight loss from about the 28 day of experimental feeding. Symptoms of polyneuritis were also evident. On the 20th day of feeding and thereafter, rats on the thiamine deficient diet had a persistent erection. This was observed in 7% of the rats on a thiamine deficient group on day 20, 30.7% on day 25, 63.6% on day 30, and 100% on day 33. Effects of thiamine hydrochloride, in a single dose of 1 mg/kg given subcutaneously on the symptoms of thiamine deficiency were investigated. The treated rats recovered from the polyneuritic symptoms, and persistent erection disappeared in one out of 5 rats on the 3rd day and in 2 more rats on the 7th day. Persistent erection disappeared completely in rats maintained on a thiamine sufficient diet 3 days after single subcutaneous administration of thiamine HCl. These observations suggest that persistent erection was brought on as a consequence of thiamine deficiency.
Mucosal biopsy specimens obtained by routine endoscopy from 108 human subjects, including one patient with thiamine deficiency, were incubated at 37 degrees C in oxygenated calcium-free Krebs-Ringer solution (pH 7.5) containing tritiated thiamine and [14C]dextran as a marker of adherent mucosal water. The amount of labeled thiamine taken up was measured radiometrically. In subjects with no clinical evidence of thiamine deficiency, 1) thiamine uptake by duodenal mucosa had a hyperbolic time course, reaching equilibrium at 10 min; 2) thiamine concentrations < 2.5 mumol/L were taken up predominantly by a saturable mechanism displaying Michaelis-Menten kinetics (K(m) 4.4 mumol/L and Jmax 2.3 pmol.mg wet tissue-1.6 min-1), whereas higher concentrations were taken up by passive diffusion; 3) thiamine transport had different capacities along the gastrointestinal tract (duodenum >> colon > stomach); and 4) thiamine uptake was competitively inhibited in the duodenum by thiamine analogs, albeit with a different order of potency compared with rats, and was blocked by 2,4-dinitrophenol. In the thiamine-deficient patient, the duodenal saturable uptake was increased, with higher K(m) and Jmax values. In conclusion, physiologic concentrations of thiamine were transported in human small intestine by a specific mechanism dependent on cellular metabolism, whose transporters appear to be down-regulated.
Pyrithiamine-induced acute thiamine-deficient encephalopathy was produced in adult male Wistar rats. Twenty-four hours before the onset of neurological signs the brain showed no morphological abnormalities. Encephalopathic rats had symmetrical lesions of edematous necrosis localized in the thalamus, mammillary body, and pontine tegmentum. Biochemically, encephalopathic rats had brain thiamine levels less than 20% of controls. For the assay of the concentrations of adenosine triphosphate (ATP) and phosphocreatine, the brains were fixed using 5 KW microwave irradiation and were divided into four parts: cerebral cortex, diencephalon, lower brainstem, and cerebellum. In the lower brainstem of the encephalopathic rats ATP concentrations were 89.5% of normal controls. Phosphocreatine levels were lowered to 70% of controls in the diencephalon and to 75% in the lower brainstem. Total high energy phosphate levels were decreased to 89% of controls in the diencephalon and 91% in the lower brainstem before the onset of neurological signs and to 76% and 79%, respectively, after the onset. In the cerebral cortex and cerebellum high energy phosphates were not significantly reduced. Lower high energy phosphate levels and the distribution of edematous lesions were coincident in the brain. These findings suggest that a low energy state is closely related to the formation of edematous lesions in thiamine-deficient encephalopathy.
The possible involvement of blood-brain barrier (BBB) breakdown in the pathogenesis of thiamine deficiency encephalopathy was investigated in RBE4 cells, an immortalized rat brain endothelial cell line. The effects of thiamine deficiency produced by addition of pyrithiamine and by reduction of thiamine in the culture medium, on the metabolism and permeability of the RBE4 monolayer was examined. Pyrithiamine treatment in low thiamine medium (M199) for 7 days caused cytotoxic effects on RBE4 cells at all concentrations (10-50 microg/ml). Pyrithiamine caused a concentration- and time-dependent decrease in MTT reduction and a significant increase in glucose consumption and lactate production compared to controls. Pyrithiamine treatment for 3 days caused a significant decrease in MTT reduction at 50 microg/ml only. In contrast, increased glucose consumption and lactate production by the RBE4 cells was observed after treatment for 3 days with concentrations of 25 microg/ml pyrithiamine and above. The permeability of RBE4 cell monolayers to [14C]sucrose (Mw 342), but not FITC-dextran (Mw 4000) was significantly increased by treatment with pyrithiamine concentrations of 25 microg/ml and above for 3 days. These effects were not accompanied by detectable changes in F-actin distribution or content, although F-actin content was significantly reduced by 7 days exposure to pyrithiamine. These results suggest that metabolic and permeability changes in thiamine-deficient RBE4 cells may be important early events in thiamine-deficiency encephalopathy. The relative role of the BBB in the pathogenesis of thiamine deficiency is discussed.
To further elucidate the molecular basis of the selective damage to various brain regions by thiamin deficiency, changes in enzymatic activities were compared to carbohydrate flux through various pathways from vulnerable (mammillary bodies and inferior colliculi) and nonvulnerable (cochlear nuclei) regions after 11 or 14 days of pyrithiamin-induced thiamin deficiency. After 11 days, large decreases (-43 to -59%) in transketolase (TK) occurred in all 3 regions; 2-ketoglutarate dehydrogenase (KGDHC) declined (-45%), but only in mammillary bodies; pyruvate dehydrogenase (PDHC) was unaffected. By day 14, TK remained reduced by 58%-66%; KGDHC was now reduced in all regions (-48 to -55%); PDHC was also reduced (-32%), but only in the mammillary bodies. Thus, the enzyme changes did not parallel the pathological vulnerability of these regions to thiamin deficiency. 14CO2 production from 14C-glucose labeled in various positions was utilized to assess metabolic flux. After 14 days, CO2 production in the vulnerable regions declined severely (-46 to 70%) and approximately twice as much as those in the cochlear nucleus. Also by day 14, the ratio of enzymatic activity to metabolic flux increased as much as 56% in the vulnerable regions, but decreased 18 to 30% in the cochlear nuclei. These differences reflect a greater decrease in flux than enzyme activities in the two vulnerable regions. Thus, selective cellular responses to thiamin deficiency can be demonstrated ex vivo, and these changes can be directly related to alterations in metabolic flux. Since they cannot be related to enzymatic alterations in the three regions, factors other than decreases in the activity of these TPP-dependent enzymes must underlie selective vulnerability in this model of thiamin deficiency.
OBJECTIVE: Polyneuropathy has been reported after gastrectomy performed to treat various lesions. Although thiamine deficiency is a possible cause of this neuropathy, the pathogenesis still remains to be clarified. Seventeen patients with peripheral neuropathy with thiamine deficiency after gastrectomy are described. METHODS: Seventeen patients with polyneuropathy after gastrectomy accompanied by thiamine deficiency were selected. Patients were restricted to those with total or subtotal gastric resection to treat ulcer or neoplasm. Patients who had undergone operations to treat morbid obesity were excluded. RESULTS: Intervals between the operation and onset of neuropathy varied from 2 months to 39 years. Most patients did not seem malnourished. Serum concentrations of B vitamins other than thiamine were nearly normal. Symmetric motor-sensory polyneuropathy, predominantly involving the lower limbs, had progressed over intervals varying from 3 days to 8 years. Relative degrees of motor and sensory impairment also varied extensively. Some cases that progressed rapidly mimicked Guillain-Barré syndrome. Electrophysiological and pathological findings were those of axonal neuropathy. Substantial functional recovery from polyneuropathy was seen in most patients by 3 to 6 months after initiating thiamine supplementation. Motor recovery was better than sensory recovery. CONCLUSIONS: Various symptoms were seen in patients with postgastrectomy neuropathy. Thiamine deficiency should be considered in the differential diagnosis of motor-sensory polyneuropathy after gastrectomy.
Several lines of evidence indicate that thiamine deficiency causes the Wernicke-Korsakoff syndrome, a human memory disorder. The present study examined behavioral deficits in rats after recovery from a bout of thiamine deficiency. Following behavioral testing, the brains were dissected into regions and assayed biochemically for levels of dopamine, norepinephrine, serotonin and the primary metabolites of these monoamines. Based on previous findings in this laboratory, we predicted that thiamine deficiency not only produces behavioral deficits but loss in catecholamines as well. Impairments were observed for a spatial delayed alternation task that had been learned prior to experimental treatment. In addition, experimental animals were impaired in their ability to acquire two novel tasks, active and passive shock avoidance, after recovery from the acute effects of thiamine deficiency. Comparable deficits were not observed for a number of reflex responses that were measured to assess the general neurological state of the animals. Biochemical analyses revealed that the concentration of norepinephrine was reduced significantly in cortex-hippocampus and olfactory bulb but not in other regions, while dopamine and serotonin levels were not altered in any brain region examined. These data demonstrate that a bout of thiamine deficiency can produce persistent deficits in brain norepinephrine and concomitant decrements in behavioral measures of learning and memory. These results are consistent with our hypothesis and evidence that noradrenergic deficits contribute to the amnesic symptoms of Korsakoff's psychosis.
BACKGROUND: The prolonged and heavy consumption of ethanol has been associated with thiamine deficiency and a wide range of cognitive and memory impairments. The present study was undertaken to test the hypothesis that ethanol and thiamine deficiency act synergistically, producing more severe clinical neurological disturbances and cognitive and memory impairments than either thiamine deficiency or chronic ethanol alone. METHODS: The acute neurological and long-term behavioral consequences of combined chronic (32 weeks) ethanol consumption (20% v/v in drinking water) and three separate 4-week long episodes of dietary thiamine deficiency (ET/TD) versus ethanol (ET) or thiamine deficiency (TD) treatments alone were examined in male Sprague Dawley rats aged 12 weeks at the start of treatment. RESULTS: The ET/TD group lost less weight than the TD group during each episode of thiamine deficiency. Contrary to expectations, the progression and severity of ataxia, impaired righting reflexes, and opisthotonic posturing were similar in the ET/TD and TD groups. None of the ET animals displayed any neurological or behavioral symptoms during treatment. After withdrawal from ethanol and a 7-week recovery period, none of the groups differed in spontaneous activity. On subsequent testing, the ET group displayed a significant increase in perseverative responding in a spontaneous alternation task. A small but significant proportion of ET/TD (23%), ET (17%), and TD (8%) animals were unable to reach criterion on an initial nonmatching-to-position task (NMTP) or in two subsequent reversals of the matching and NMTP tasks, which indicated persistent learning impairments. A large proportion of animals in each of the three groups demonstrated significantly reduced accuracy compared with controls at longer delays of matching-to-position tasks (MTP), but only the ET group was consistently impaired at the shorter delays. There were no significant correlations between blood ethanol concentration and any of the learning and memory measures. CONCLUSIONS: These results indicate that the interaction of chronic ethanol consumption and bouts of TD is both domain specific and not always synergistic. Learning and reference memory appear to be sensitive to a synergistic interaction of ET and TD, whereas short-term working memory disturbances are most affected by ET and neurological symptoms are most associated with TD. Furthermore, neither the presence of neurological symptoms nor blood ethanol concentrations appear to be good predictors of learning and memory deficits.
Pyrithiamine-induced thiamin deficiency has been used in rat as an experimental form of Wernicke-Korsakoff encephalopathy, a disease associated with chronic alcoholism. Although the main etiological factor is known to be the lack of thiamin, the biochemical mechanisms involved in the pathogenesis remain unclear. Thiamin-dependent enzymes were studied in brain mitochondria: alpha-ketoglutarate dehydrogenase activity exhibited 40% reduction, whereas pyruvate dehydrogenase did not change significantly. Polarographic recordings of mitochondrial respiration revealed a decreased State 3, when using pyruvate/malate, alpha-ketoglutarate or glutamine as a substrate, but the respiration rates remained unchanged with glutamate or succinate. This fall in pyruvate oxidation may be due to the impairment of alpha-ketoglutarate dehydrogenase, which follows pyruvate dehydrogenase in the metabolic pathway. A time course of lactate concentration showed dramatic increases in thalamus, mid brain, hypothalamus and colliculli, consistent with the anatomopathological findings. No increases were found before the onset of neurological symptoms.
During 30 days of thiamine deficiency (TD) feeding, the rat antinociceptive effect (pain threshold) to noxious heat stimulation was significantly increased in proportion to the decrease substance P (SP) fluorescent intensity in the spinal cord. Only a single injection of thiamine HCl (0.5 mg/kg, s.c.) on the early treatment day during TD feeding effectively reversed the analgesic effect to the pair-fed control level. Whereas this reversal effect by thiamine treatment was not found if this treatment was done on the relatively late day. However, either treatment day, except muricide, complete disappearance of various animal behaviours induced by TD was found. These results indicate that, after certain degree of TD development, TD-induced behavioral effects might be reversible, but the afferent nerve fibers might be irreversibly damaged, probably by the similar mechanism as found for an excitotoxin(s) mediated injury in the certain brain region(s). The results also suggest a possibility that SP and an excitotoxin, glutamate, in the dorsal part of the spinal cord greatly contribute to the pain transmission induced by noxious heat stimulation.
The nature and histologic environment of birefringent crystals found incidentally at necropsy in the liver and adrenal glands of dogs fed a thiamine-deficient diet were studied. The crystals were identified as calcium stearate by ultrastructural and x-ray microdiffraction techniques. Crystals were observed intracellularly within cytoplasmic vacuoles and extracellularly within sinusoids. Generally, crystals were also observed in pair-fed controls that were given a purified diet (equal in weight to that consumed by the thiamine-deficient animals) plus supplemental thiamine. Crystal deposits were found in trace amounts in a few of the ad libitum-fed controls. Although thiamine deficiency may be involved in promoting crystal deposition in the adrenal cortex, calcium stearate crystal formation within the adrenal glands and the liver appears unrelated to dietary thiamine deficiency per se, but is probably related to deficiency of an unidentified nutrient in the purified thiamine-deficient diet.
Parenteral nutrition with carbohydrates is limited, inter alia, by the occurrence of a dose-dependent hyperlactataemia. Thiamine deficiency, which can be provoked by an eight weeks' diet which is deficient in thiamine, will produce clearly elevated lactate levels in rats, leading eventually to lactate acidosis as a result of glucose load, compared with a control group on a normal diet. It is recommended to initiate a high-dosage level thiamine therapy before parenteral feeding with carbohydrates, if thiamine deficiency appears possible on the grounds of previous history of the case (alcohol abuse) or because of the underlying disease (e.g. oesophageal strictures, carcinoma of the oesophagus).