Rates of local cerebral protein synthesis in fetal and neonatal sheep

During gestation there is likely to be a constantly changing rate of protein synthesis in the brain that may exhibit regional specificity. With the use of the quantitative autoradiographic L-[1-(14)C]leucine method for the determination of local rates of leucine incorporation into cerebral protein (lCPS(Leu)), we have sought to characterize this important process. lCPS(Leu) was measured in nine fetal sheep (118-139 days gestational age) and five newborn lambs (1-5 days of age). In other experiments, the fraction of leucine in the precursor pool for protein synthesis in the brain derived from the arterial plasma was determined to be 0.57 +/- 0.04 (mean +/- SE) in one fetus and two lambs. This value was used in the calculation of lCPS(Leu) in 35 regions of the central nervous system, pineal body, and whole brain. Regardless of age, lCPS(Leu) was highest in the pineal body, brain stem, and hypothalamic nuclei and lowest in white matter. In sensorimotor cortex, corona radiata, pyramidal tracts, and whole brain, lCPS(Leu) was positively correlated with prenatal age (P < or = 0.05). These increases in lCPS(Leu) probably reflect myelination in the cerebrum, which is known to occur in late gestation.

Validity of utilization management criteria for psychiatry

OBJECTIVE

This study examined the validity of four psychiatric utilization management criteria sets: the 1992 and 1993 InterQual Intensity, Severity, and Discharge (ISD) criteria, the Managed Care Appropriateness Protocol, and an instrument developed by the Department of Veterans Affairs (VA).

METHOD

The appropriateness of acute care admission and continued stay for 70 randomly selected VA psychiatric inpatients was retrospectively assessed with each criteria set. The sensitivity and specificity of each instrument were evaluated by comparing its assessments to the consensus of judgments of a panel of expert psychiatrists who reviewed the same cases. Sensitivity was defined as the proportion of admissions or continued-stay days the panel found appropriate for acute care that the criteria judged to be appropriate for acute care; specificity was the proportion the panel found inappropriate for acute care that the criteria judged to be inappropriate for acute care.

RESULTS

For admissions, there were only minor differences in the validity of the four criteria sets as assessed by agreement with the panel's judgments. For each of 4 continued-stay days studied, either the sensitivity or specificity of the 1993 InterQual ISD criteria was below 0.30. The specificity of the 1992 InterQual ISD criteria was below 0.60 for 2 days. In contrast, for the Managed Care Appropriateness Protocol, sensitivity was 0.73-0.93 and specificity was 0.78-0.88 over the 4 days.

CONCLUSIONS

The findings raise major concerns about the validity of the widely used InterQual ISD psychiatry criteria, suggest that the Managed Care Appropriateness Protocol may be a useful tool for psychiatric utilization management, strongly underline the need to validate all criteria used to assess medical care, and support the appropriateness of the procedures used to perform these assessments.

Positive correlations between cerebral protein synthesis rates and deep sleep in Macaca mulatta

Local rates of cerebral protein synthesis (ICPSleu) were determined with the autoradiographic L-[1-14C]leucine method in seven awake and seven asleep, adult rhesus monkeys conditioned to sleep in a restraining chair in a darkened, ventilated chamber while EEG, EOG, and EMG were monitored. Prior to the period of measurement all animals slept for 1-4 h. Controls were awakened after at least one period of rapid-eye-movement (REM) sleep. Experimental animals were allowed to remain asleep, and they exhibited non-REM sleep for 71-99% of the experimental period. Statistically significant differences in ICPSleu between control and experimental animals were found in four of the 57 regions of brain examined, but these effects may have occurred by chance. In the sleeping animals, however, correlations between ICPSleu and percent time in deep sleep were positive in all regions and were statistically significant (P < or = 0.05) in 35 of the regions. When time in deep sleep was weighted for the integrated specific activity of leucine in grey matter, positive correlations were statistically significant (P < or = 0.05) in 18 regions in the experimental animals. These results suggest that rates of protein synthesis are increased in many regions of the brain during deep sleep compared with light sleep.

Zipeprol: preclinical assessment of abuse potential

Zipeprol was evaluated in a number of in vitro and in vivo assays predictive of stimulant, depressant, or opioid abuse potential. Zipeprol had affinity for mu and kappa opioid binding sites as well as sigma binding sites. However, it failed to exert opioid-like agonist actions in rodents, and did not attenuate withdrawal signs in morphine- or pentobarbital-dependent rats. Zipeprol did not substitute for either amphetamine or pentobarbital in drug discrimination assays in rhesus monkeys. On the other hand, it suppressed morphine withdrawal signs in rhesus monkeys in two assays, and it acted as a quadazocine-sensitive reinforcer in monkeys trained to self-inject alfentanil. Zipeprol also acted as a reinforcer in monkeys trained to self-inject methohexital. In a dose range of 10-18 mg/kg, zipeprol induced convulsions in monkeys. Zipeprol appears to have abuse potential and a novel spectrum of action involving both opioid and non-opioid effects.

Plasticity of metabolic whisker maps in somatosensory brainstem and thalamus of mice with neonatal lesions of whisker follicles

We employed the autoradiographic deoxyglucose method to study metabolic whisker maps of the adult mouse somatosensory brainstem and thalamus after the neonatal removal of left whisker follicles C1, C2 and C3. Left whiskers B1-3 and D1-3 were deflected to metabolically activate the somatosensory pathway. Unoperated mice that were stimulated in the same fashion served as controls. Whisker stimulation resulted in an ipsilateral increase in metabolic activity in the three trigeminal brainstem structures in which the whiskers are represented topologically by segments of high cytochrome oxidase activity, i.e. subnucleus caudalis, subnucleus interpolaris and nucleus principalis. In the two subnuclei of mice with lesions and of controls, there was an increase in metabolic activity of the representations of the deflected whiskers, whereas the metabolic activity of representations A1-3 and E1-3 was low. Apart from these similarities, the metabolic activation of the representations originally representing whiskers C1-3 was remarkably greater in mice with lesions than in controls. This increase reached statistical significance in subnucleus caudalis and approached statistical significance in subnucleus interpolaris. In nucleus principalis the deprived territory was only partially activated and the degree of metabolic activation was less than in the subnuclei. In the thalamic ventrobasal complex of mice with lesions metabolic activity was unpatterned whereas two areas of metabolic activation were distinct in controls. Hence, the removal of whisker follicles in newborn mice resulted in the suppression of localized metabolic responses to whisker stimulation in the thalamus, whereas in the brainstem stimulus-related activity was prominent and the deprived territory became responsive to the stimulation of whisker follicles adjacent to the lesion. Apparently, the modification of the whisker representation at the first synapse of the pathway induces a diminution of localized responsivity in the thalamus.

Platelet alpha 2-adrenoreceptors, catecholamines, hemodynamic variables, and anxiety in panic patients and their asymptomatic relatives

The objectives of this study were to a) replicate our prior finding of a decreased number (Bmax) of platelet alpha 2-adrenoreceptors in panic disorder, b) determine if binding is also decreased in asymptomatic first-degree relatives of panic patients (known to be at increased risk for developing panic), and c) evaluate the effect of treatment on the presumptive decrease in binding (i.e., is the decrease a state or a trait marker for panic?). Panic patients had clonidine and yohimbine platelet-binding assays, symptom ratings, and measurement of lying and standing plasma epinephrine, norepinephrine, systolic and diastolic blood pressure, and heart rate before treatment, after approximately 2 months of medication (fluoxetine, tricyclics, or alprazolam) and/or cognitive behavioral treatment, and after symptom remission while drug free; normal subjects had determinations of the same measures at approximately the same time intervals. Relatives of both groups had one determination only of all measures. Tritiated clonidine binding was decreased and lying heart rate was increased in patients before treatment. Magnitude of binding decrease was correlated with symptom severity and standing norepinephrine. No binding abnormality was seen in first-degree relatives of patients. Treatment increased clonidine binding in patients. Both patients and relatives of patients showed significantly increased standing plasma norepinephrine in comparison to controls. There is a state-related decrease in binding, associated with symptom severity and norepinephrine, in panic disorder. Abnormal reactivity of norepinephrine to standing might be a marker for increased likelihood of panic development in individuals at risk.

Imaging exocytosis and endocytosis

From the secretion of neurotransmitters via synaptic vesicles to the expulsion of cellular waste via contractile vacuoles, exocytosis and its sequel, endocytosis, are being explored with a variety of new optical tools. Fluorescent markers, especially styryl dyes such as FM1-43 (which reversibly labels endosomal membranes), have been used to follow exo- and endocytic events in many cell types. Even though the development of new dyes is still largely empirical, some theoretical principles have emerged to guide future dye chemistry. Moreover, advances in optical imaging technology that augment conventional fluorescence microscopy are appearing. For example, interference reflection microscopy (which requires no flurophore) and total internal reflection microscopy have recently been used to observe single exocytic events at the contact point between a glass coverslip and the plasma membrane.

Simultaneous independent measurement of endocytosis and exocytosis

Studies of membrane traffic between the cytoplasm and surface of a cell suggest that membrane internalization is tightly coupled to secretion. Studies using the capacitance technique show that endocytosis can follow evoked exocytosis within a second or less. The capacitance technique, however, measures only the net change in cell surface area, and thus separating exocytosis from endocytosis requires that the two events do not overlap in time. This condition is probably met with small, brief stimuli, but during prolonged stimulation it is more likely that exocytosis and endocytosis occur simultaneously, We used FM1-43 fluorescence, which provides a cumulative measure of exocytosis, independent of endocytosis, in combination with capacitance monitoring to track unidirectional movements of membrane simultaneously and in real time in bovine adrenal chromaffin cells. We confirm that, with relatively small stimuli, exocytosis ceases before endocytosis begins (no overlap). In contrast, during prolonged stimulation, the onset of endocytosis is delayed by 2-3 min, but then the rate of endocytosis quickly grows to equal that of exocytosis. The delayed onset of endocytosis may be an emergency defence against catastrophic cell swelling.

Overutilization of acute-care beds in Veterans Affairs hospitals

The authors tested the hypothesis that the Department of Veterans Affairs (VA) hospitals would have substantial overutilization of acute care beds and services because of policies that emphasize inpatient care over ambulatory care. Reviewers from 24 randomly selected VA hospitals applied the InterQual ISD* (Intensity, Severity, Discharge) criteria for appropriateness concurrently to a random sample of 2,432 admissions to acute medical, surgical, and psychiatry services. Reliability of hospital reviewers in applying the ISD* criteria was tested by comparing their reviews with those of a small group of expert reviewers. Validity of the ISD* criteria was tested by comparing the assessments of master reviewers with the implicit judgments of panels of nine physicians. The physician panels validated the ISD* admission criteria for medicine and surgery (74% agreement with master reviewers, kappa > 0.4), whereas the psychiatry criteria were not validated (66% agreement, kappa 0.29). Hospital reviewers reliably used all three criteria sets (> 83% agreement with master reviewers, kappa > 0.6). Rates of nonacute admissions to acute medical and surgical services were > 38% as determined by the hospital and master reviewers and by the physician panels. Nonacute rates of continued stay were > 32% for both medicine and surgery services. Similar rates of nonacute admissions and continued stay were found for all 24 hospitals. Reasons for nonacute admissions and continued stay included lack of an ambulatory care alternative, conservative physician practices, delays in discharge planning, and social factors such as homelessness and long travel distances to the hospital. Using criteria that the authors showed to be reliable and valid, substantial overutilization of acute medicine and surgical beds was found in a representative sample of VA hospitals. Correcting this situation will require changes in physician practice patterns, development of ambulatory care alternatives to inpatient care, and modification of current VA policies determining eligibility for care.

Changes in the regulation of 5-hydroxytryptamine release by alpha2-adrenoceptors in the rat hippocampus after long-term desipramine treatment

In vivo microdialysis was used to measure the effects of long-term treatment of rats with desipramine upon the regulation by alpha2-adrenoceptors of serotonin (5-hydroxytryptamine, 5-HT) release from the serotonergic neurons in the hippocampus. Rats were injected with saline or desipramine, 10 mg/kg, i.p., every 12 h for 14 days. When added to the perfusion solution, brimonidine, an alpha2-adrenoceptor agonist, significantly inhibited the K+-evoked release of 5-HT in the hippocampi of saline-treated, control rats. This action of brimonidine was prevented by pretreating the rats with idazoxan, an alpha2-adrenoceptor antagonist. Long-term desipramine treatment significantly reduced the inhibitory effect of brimonidine upon the K+-evoked 5-HT release. With long-term administration of desipramine, noradrenaline content in the hippocampi was significantly decreased as compared with that of the control rats, whereas the basal noradrenaline concentration in the dialysate was significantly increased. On the other hand, both the 5-HT content of the hippocampus and the basal 5-HT concentration in the dialysate were significantly increased. The present study suggests that long-term administration of desipramine causes a functional subsensitivity of the presynaptic alpha2-adrenoceptors that regulate serotonergic neuronal function in the rat hippocampus. It also supports the concept that changes in the sensitivity of alpha2-adrenoceptors that regulate neurotransmitter release play an important role in the mechanism of antidepressant drug action.

Effects of aging on regional rates of cerebral protein synthesis in the Sprague-Dawley rat: examination of the influence of recycling of amino acids derived from protein degradation into the precursor pool

The quantitative autoradiographic L-[1-14C]leucine method for determination of regional rats of cerebral protein synthesis (1CPSleu) requires knowledge of the degree of recycling of leucine derived from protein degradation into the precursor pool of protein synthesis. The influence of recycling can be evaluated by measuring lambda, the steady state ratio of the leucine specific activity in the precursor amino acid pool (t-RNA-bound leucine) to that in the arterial plasma. To define the changes in 1CPS(leu) during the process of normal aging in the rat we have evaluated lambda in middle-aged (14 months) and aged (24 months) rats and compared its values with those obtained previously in young adult rats (two months of age). The results show that the value of lambda is the same in all three age groups, and that there is no change with aging in the fraction of leucine in the precursor pool derived from protein degradation. Our previously reported regional rates of protein synthesis in young adult and aged rats were based on the assumption that there was no recycling of leucine derived from protein degradation into the precursor pool of protein synthesis [Ingvar M.C., Maeder P., Sokoloff L. and Smith C.B. (1985) Brain 108, 155-170]. These values have been recalculated in the present study in order to take into account the appropriate correction for recycling. The recalculated rates are higher than those reported previously, but the effects of aging in the brain as a whole and in some specific brain regions are confirmed. Decreased 1CPS(leu) was observed by middle-age, and in this cross-sectional study did not appear to decrease further. Of the 39 brain regions examined decreases were found throughout the brain with some proclivity for the brain stem. In comparison with young adults the weighted average rate of protein synthesis in the brain as a whole was found to be decreased by 16 and 11% in the middle-aged and aged groups, respectively.

Whisker follicle removal affects somatotopy and innervation of other follicles in adult mice

The present study shows that in the whisker-to-barrel pathway of adult mice surgical removal of three whisker follicles leads to the expansion of the functional cortical representation of the whiskers adjacent to the lesion into the deprived barrels within 8 months. Concomitant with this enlargement, there is an increase in follicular innervation of the corresponding whiskers. This reorganization of the peripheral innervation may be important for the observed reshaping of cortical somatotopy.

Influence of valine flooding on channeling of valine into tissue pools and on protein synthesis

Rates of valine incorporation into protein were measured under control and valine-"flooding" conditions and included correction for the degree of recycling of unlabeled valine derived from the steady-state breakdown of tissue protein into the precursor pool (tRNA bound). The correction factor lambda, which is the ratio of the steady-state specific activity of valine in the tissue tRNA-bound pool to that in the arterial plasma, was determined for each of the tissues. In controls, values of lambda ranged from 0.31 in adrenals to 0.54 in heart; in flooded animals, values were higher, but only in liver was the value of lambda close to 1.0. In control and flooded rats, rates of protein synthesis were highest in liver and adrenals and lowest in skeletal muscle, with intermediate values in brain and heart. Flooding resulted in increased rates of protein synthesis in liver and decreased rates in adrenals. Rates of protein synthesis in brain, heart, and skeletal muscle were not statistically significantly affected by flooding.

Rates of local cerebral protein synthesis in the rat during normal postnatal development

The degree of recycling of leucine derived from protein breakdown into the precursor pool for protein synthesis was measured in rat brain at different postnatal ages, and age-specific values were used in the calculation of regional (local) rates of cerebral leucine incorporation into protein (lCPSleu) in 44 brain regions and the brain as a whole. Early in development, a greater fraction of the precursor leucine pool is derived from protein breakdown, indicating that protein degradation is higher in young rats compared with adults. In whole brain and in most regions, values for lCPSleu were highest at 10 days and gradually decreased with age. By 60 days of age, values in cortex were approximately 60% of those at 10 days of age. In the paraventricular and supraoptic nuclei of the hypothalamus, however, lCPSleu increased during development, reaching peak values in adults. In white matter of the cerebellum and the cerebrum, peaks of lCPSleu were reached at 14 and 21 days, respectively, approximately at the times of maximum rates of myelination.

Differential regulation by anti-tumor-promoting 12-deoxyphorbol-13-phenylacetate reveals distinct roles of the classical and novel protein kinase C isozymes in biological responses of primary mouse keratinocytes

12-Deoxyphorbol-13-phenylacetate (dPP) is the prototype for a new class of phorbol derivatives that function as protein kinase C (PKC) activators with potent anti-tumor-promoting activity. To explore the mechanism of action of dPP, we have conducted detailed analyses of the translocation and down-regulation patterns of individual PKC isozymes in mouse primary keratinocytes upon dPP treatment. PKC-alpha, -delta, and -epsilon were very quickly (within 2-5 min) translocated from the soluble fraction to the Triton X-100-soluble particulate fraction. PKC-delta and -epsilon were translocated with 2 orders of magnitude higher potency than was PKC-alpha. After translocation, PKC-alpha, -delta, -eta, and -epsilon were down-regulated; the down-regulation of PKC-epsilon contrasts with its retention after phorbol-12-myristate-13-acetate or bryostatin treatment. As was the case with translocation, dPP down-regulated the novel PKC isozymes (delta, epsilon, and eta) with 2 orders of magnitude higher potency (ED50, about 1-2 nM), compared with PKC-alpha (ED50, about 100 nM). dPP induced transglutaminase activity, ornithine decarboxylase activity, and cornification with potencies similar to that for PKC-alpha translocation. On the other hand, dPP caused inhibition of EGF binding with a potency similar to that for the translocation of the novel PKC isozymes. Although the generality of its selectivity in different cell types remains to be determined, at least in keratinocytes dPP is a powerful tool for dissecting the involvement of the classical and novel PKC isozymes in biological responses. The unique regulatory pattern of PKC-epsilon could contribute to the anti-tumor-promoting activity of dPP.

Effects of acute and delayed effects of prior chronic cocaine administration on regional rates of cerebral protein synthesis in rats

Single or repeated treatments with cocaine (15 mg/kg, i.p.) in rats modify rates of local cerebral protein synthesis (ICPSleu) measured with the [1-14C]leucine method. A single dose of cocaine to naive rats reduced ICPSleu by about 10% throughout the brain; the most statistically significant reduction was in the nucleus accumbens, shell portion (P = .0003). A comparable dose of cocaine administered acutely after 1 wk of daily cocaine injections had no effects on ICPSleu. Delayed effects of prior chronic cocaine treatment were studied in experiments in which one rat of each pair received injections with saline for 8 days and the other cocaine, and on the 15th day ICPSleu was measured. In these experiments delayed effects of the chronic cocaine treatment were observed; in the cocaine-treated rats ICPSleu was significantly increased in selective brain regions, i.e., prefrontal and primary olfactory cortex (P < .006). These results suggest that acute effects of a single dose of cocaine and residual effects of chronic cocaine treatment on ICPSleu are distinctly different and occur in different regions of the brain.

Dissociation of phorbol esters leads to immediate redistribution to the cytosol of protein kinases C alpha and C delta in mouse keratinocytes

We have measured the dissociation rate of phorbol 12-myristate 13-acetate (PMA), a potent tumor promoter, phorbol 12,13-dibutyrate (PDBu), a weak tumor promoter, and 12-deoxyphorbol 13-phenylacetate (dPP), an antitumor promoter, from intact mouse keratinocytes. PDBu and dPP showed a very rapid release from the cells (t1/2 = 1 min), whereas PMA showed a slower release (t1/2 = 9 min). Western blot analysis of the amounts of protein kinase C alpha (PKC alpha) and PKC delta in the soluble fraction and the Triton X-100-soluble particulate fraction revealed that translocation of both isozymes from the soluble to the particulate fraction was reversible when the phorbol esters were washed off. Washes of 5-15 min resulted in complete redistribution of the PKC isozymes when the cells were previously treated with 1 microM dPP or 1 microM PDBu for 5 min. In the case of treatment with 100 or 10 nM PMA, the redistribution required a longer time; nevertheless, the PKC isozymes returned to the soluble fraction within 60 min. Longer initial treatments with PMA, dPP, and PDBu (up to 60 min) translocated PKC in a very similar, completely reversible fashion. We conclude that in this cell line phorbol esters do not induce the conversion of PKC isozymes to an integral membrane state.

Bryostatin 1 protects protein kinase C-delta from down-regulation in mouse keratinocytes in parallel with its inhibition of phorbol ester-induced differentiation

Bryostatin 1 and phorbol-12-myristate-13-acetate (PMA) are both potent activators of protein kinase C (PKC), although in primary mouse keratinocytes bryostatin 1 does not induce differentiation and blocks PMA-induced differentiation. We report here that in primary mouse keratinocytes PMA caused translocation of PKC-epsilon to the Triton X-100-soluble fraction with an approximately 2-order of magnitude higher potency, compared with translocation of PKC-alpha and PKC-delta. The kinetics of translocation were fastest for PKC-epsilon, slower for PKC-alpha, and slowest for PKC-delta. At 5-20 min bryostatin 1 showed potency similar to that of PMA for translocating PKC-alpha, higher potency for translocating PKC-delta, and lower potency for translocating PKC-epsilon. At a later time (6 hr), bryostatin 1 was 1-2 orders magnitude more potent than PMA for causing loss of PKC-alpha, -delta, and -epsilon from the soluble fraction. Bryostatin 1 was 40-fold more potent than PMA for down-regulating PKC-alpha and showed a biphasic dose-response curve for down-regulating PKC-delta. Bryostatin 1 at 0.1-1 nM down-regulated PKC-delta to a similar extent as did PMA. Bryostatin 1 at 100 nM to 1 microM, on the other hand, failed to induce down-regulation, and these high (100 nM to 1 microM) doses of bryostatin 1 showed noncompetitive inhibition of PKC-delta down-regulation by 1 microM PMA after coapplication. This protected portion of PKC-delta retained kinase activity. The dose-response curve for bryostatin 1 protection of PKC-delta from down-regulation by PMA correlated with bryostatin 1 inhibition of the effects of PMA on cornified envelope formation (a marker of differentiation) and epidermal growth factor binding. Although PKC-epsilon was readily translocated by both PMA and bryostatin 1, the PKC-epsilon originally associated with the particulate fraction showed no down-regulation by either of these agents. We hypothesize that differential regulation of PKC isozymes by PMA and bryostatin 1 may contribute to the different patterns of biological responses that they induce.

Effects of prolonged sleep deprivation on local rates of cerebral energy metabolism in freely moving rats

Although sleep deprivation interferes with biological processes essential for performance, health, and longevity, previous studies have failed to reveal any structural or functional changes in brain. We have therefore measured local rates of cerebral glucose utilization (ICMRglc) with the quantitative autoradiographic 2-14C-deoxyglucose method in an effort to determine if and, if so, where sleep deprivation might affect function in sleep-deprived rats. Sleep deprivation was maintained for 11-12 d, long enough to increase whole body energy metabolism, thus confirming that pathophysiological processes that might involve brain functions were evolving. Deep brain temperature was also measured in similarly treated rats and found to be mildly elevated relative to core body temperature. Despite the increased deep brain temperature, systemic hypermetabolism, and sympathetic activation, ICMRglc was not elevated in any of the 60 brain structures examined. Average glucose utilization in the brain as a whole was unchanged in the sleep-deprived rats, but regional decreases were found. The most marked decreases in ICMRglc were in regions of the hypothalamus, thalamus, and limbic system. Mesencephalic and pontine regions were relatively unaffected except for the central gray area. The medulla was entirely normal. The effects of sleep deprivation on brain tended, therefore, to be unidirectional toward decreased energy metabolism, primarily in regions associated with mechanisms of thermoregulation, endocrine regulation, and sleep. Correspondence was found between the hypometabolic brain regions and some aspects of peripheral symptoms.

Effects of chronic dietary aluminum on local cerebral glucose utilization in rats

Beginning at 4 weeks of age normal, male, Sprague-Dawley rats were reared on Purina Laboratory Chow and drinking water containing 100 microM AlCl3. After 2 years, local rates of cerebral glucose utilization were determined with the autoradiographic [14C] deoxyglucose method in the brain as a whole and in 25 brain regions in 6 treated rats and 4 age-matched controls. The results indicate that any effects of chronic aluminum in the diet on rates of cerebral glucose utilization are small. In the brain as a whole, the mean rate of glucose utilization in the aluminum-treated rats was 6% lower than that of the controls (p = 0.09). In 21 of the 25 brain regions examined mean rates of glucose utilization were generally lower in the aluminum-treated rats but in none of the region were the effects statistically significant.