Local cerebral glucose utilization in the free moving mouse: a comparison during two stages of the activity-rest cycle.

The 2-deoxy-D[1-14C]glucose ([14C]DG) technique has been applied to the free moving mouse for the quantitative determination of local cerebral glucose utilization (LCGU). Reproducible values for LCGU were obtained indicating that the [14C]DG method had a sufficient resolution power to allow visualization and quantification of very small structures provided that glucose and [14C]DG plasma concentrations were measured on microsamples, autoradiographs prepared from proper tissue sections and suitable techniques used for analysis of the maps thus obtained. LCGU was measured in free moving mice during two stages of the light-dark cycle, one corresponding to a period of rest and the other to a period of high motor activity. In the two groups of animals LCGU was heterogeneous in the grey matter, the highest values being found in the auditory regions, the cerebellar and vestibular nuclei. LCGU was found to be lower in drowsy animals during the day than in active animals during the night and the difference was significant in the 8 following structures: the sensorimotor cortex, the septal nuclei, the nucleus of the olfactory tract, the basal amygdaloid nucleus, the ventral nucleus of the thalamus, the lateral geniculate body, the medial geniculate body and the auditory cortex. On the contrary, the suprachiasmatic nucleus was very active during the day and relatively inactive during the night as previously reported in the rat.

Local cerebral glucose utilization during waking and slow wave sleep in the cat. A [14C]deoxyglucose study.

Local cerebral glucose utilization (LCGU) was measured during spontaneous waking and slow wave sleep (SWS) by an adaptation of the [14C]deoxyglucose method to the free moving cat. In awake animals heterogeneous rates of LCGU were observed throughout the brain with values extending from 8 mumol x 100 g-1 x min-1 for white matter, to 113 for the inferior colliculus. There was no significant difference for LCGU in SWS compared with awake animals.

Glucose utilization increases in choroid plexus during slow wave sleep. A [14C] deoxyglucose study in the cat.

Glucose utilization (GU) was measured during spontaneous waking and slow-wave sleep (SWS) by adaptation of the [14C]deoxyglucose method to the unrestrained cat. In sleeping animals a greater autoradiographic signal between choroid plexus (CP) and the rest of brain was noticed. Quantification provided an index of the metabolic rate of CP and confirmed that mean values for GU were significantly higher in "sleeping' than in "awake' cats.

[Local cerebral consumption of glucose in the mouse. Adaptation of the 14C deoxyglucose method to free-moving small mammals]. / Consommation cérébrale locale de glucose chez la souris. Adaptation de la méthode du [14C] désoxyglucose à un petit mammifère libre de se mouvoir.

Local cerebral glucose utilisation (LCGU) was measured with the [14C] deoxyglucose ([14C] DG) method in the awake, free moving Mouse. Values vary from 112 mumoles. 100 g-1. min.-1 in the superior colliculus, the most active structure, to 22 mumoles. 100 g-1. min.-1 in the internal capsule. Glucose consumption is high in fasciculus retroflexus, a result peculiar to the Mouse when compared to the other Mammals were studied so far with this method. The modifications in plasma sampling proposed in this paper should facilitate the use of the [14C] DG method in free moving animals as small as the Mouse, and allow for study of the effects of behavior on local cerebral energy consumption.

[Local brain consumption of glucose during waking and slow wave sleep in the cat]. / Consommation cérebrale locale de glucose au cours de l'éveil et du sommeil lent chez le chat.

Local cerebral glucose utilization (LCGU) was measured during spontaneous waking and slow wave sleep (SWS) by adaptation of the [14C] deoxyglucose method to the unrestrained Cat. During waking LCGU ranges from 12 micromoles. 100g-1.mn-1 for white matter to 113 for the inferior colliculus. During SWS most regions exhibit higher levels of LCGU. Thus it appears that there is no decrease of cerebral metabolic activity during SWS in the Cat.

[The dopaminergic innervation of neostriatum: a new possibility of radioautographic investigation (author's transl)]. / Innervation dopaminergique du néostriatum: nouvelle possibilité d'investigation radioautographique.

Precise knowledge of the ultrastructural features and interneuronal relationships of dopaminergic (DA) axon terminals or varicosities in neostriatum is still lacking. This ignorance is due to current limitations of the methods applicable to their specific visualization at electron microscopic level. High resolution radioautography, in particular, has not yet permitted a clearcut identification of the DA nerve endings which take up and store exogenous catecholamines in vivo, due to an apparent mobilization of tracer during standard histological preparative procedures for light and electron microscopy (Fig. 1 A). In this context, histological processing of the central nervous system by vascular perfusion, tested in adult rats subjected to prolonged lateroventricular instillation of [3H]DA, led to the following results and conclusions: 1 Axonal varicosities having accumulated [3H]DA in vivo may be detected in great number in the ipsilateral paraventricular neostriatum (Figs. 1 B and 1 C). 2 The specificity of this radioautographic labelling is evidenced by: (a) its disappearance or persistance, depending on the addition of a high concentration of non-radioactive noradrenaline or serotonin to the [3H]DA solution (Fig. 1 C); (b) the absence of labelled axonal varicosities in the supraependymal region (Figs. 2 E and 2 F) and suprachiasmatic nucleus (Fig. 1 E to be compared with 1 F) after administration of [3H]DA alone; (c) the absence of any localized accumulation of [3H]DA in neostriatum following prior destruction of the nigro-striatal DA system by 6-hydroxydopamine (Fig. 1 D). 3 It seems that carrying out the double fixation with glutaraldehyde and osmium by vascular perfusion is the prerequisite for retaining in situ the [3H]DA accumulated in vivo by neostriatal nerve endings. 4 Preliminary ultrastructural examination shows that the DA axonal varicosities of paraventricular neostriatum are of small caliber (mean diameter: 0.5 micron) and mostly contain clear synaptic vesicles, occasionally associated with a few larger dense-core vesicles (figs. 2 A-D). Several of these nerve endings establish axo-dendritic synaptic junctions (Fig. 2 C) and a few, perhaps, axo-somatic contacts (Fig. 2 D).

Application of the 2-deoxy-D-[14C]-glucose method to the mouse for measuring local cerebral glucose utilization.

The 2-deoxy-D-[14C]-glucose method for the quantitative determination of local cerebral glucose utilization has been applied to the mouse. The experiments were conducted in awake freely moving animals. Local cerebral glucose utilization was found to vary widely throughout the brain with the lowest values in white matter and the highest in gray matter. The most metabolically active structures were those involved in auditory function or in general motor activity. All the values were lower than those observed previously in the conscious rat. The use of free-moving animals may be of importance since it allows the study of physiological or pathological behavioral states.

[Adaptation of the deoxyglucose method to the cellular level: histologic preparation of the central nervous system for high resolution radioautography]. / Adaptation de la méthode au désoxyglucose à l'échelle cellulaire: préparation histologique du système nerveux central en vue de la radio-autographie à haute résolution.

Vascular perfusion of all products required for primary fixation, postfixation, dehydration and embedding of nervous tissue in Epon permits radio-autographic detection of radioactivity accumulated in the central nervous system after intravenous injection of [3H]deoxyglucose. This histological technique should allow application of the deoxyglucose method at cellular if not subcellular level, since a high proportion of the tracer appears to be retained in situ in specimens adequately preserved for light and electron microscope radio-autography.

Functional plasticity in the immature striate cortex of the monkey shown by the [14C]deoxyglucose method.

Autoradiographic representation of the local rates of cerebral glucose utilization and local cerebral functional activity by means of the [14C]deoxyglucose technique reveals the existence of the ocular dominance columns in the striate cortex of the monkey in the first day of life. In contrast to the stability of these columns in more mature brain, monocular deprivation for 3 months from the first day of life results in their complete disappearance and a reversion of the autoradiographic pattern to that seen in animals with normal binocular vision. These results are consistent with a reorganization of the representation of the visual fields of the two eyes in the striate cortex and provide additional evidence of the plasticity of the striate cortex of the monkey in early life.

Metabolic mapping of the primary visual system of the monkey by means of the autoradiographic [14C]deoxyglucose technique.

An autoradiographic technique that employs 2-[14-C]deoxyglucose to measure the local rates of glucose utilization within the brain has been applied to the binocular visual system of the Macaque monkey. This method, which pictorially displays the relative rates of glucose consumption in the component structures of the brain, delineates the regions of altered functional activity because of the close relationship between functional activity and energy metabolism. Bilateral retinal stimulation results in the delineation of different rates of glucose consumption in at least four cytoarchitectural layers of the striate cortex. The most intense metabolic activity appears to be in Layer IV, the locus of the termination of the geniculocortical pathway. Bilateral visual occlusion lowers the rates of glucoes consumption in striate cortex and markedly reduces the metabolic differentiation of the various layers. Unilateral visual deprivation delineates the laminae of the lateral geniculate body and the ocular dominance columns of the striate cortex. It also results in the autoradiographic visualization of regions with normally monocular input in the striate cortex, such as the rostral portions of the mushroom-like configurations in the calcarine cortex, which represent the extreme temporal crescents of the visual fields, and small regions in the most caudal part of the mushroom configurations, which are believed to represent the cortical loci of the blind spotsof the visual fields.

Mapping of functional neural pathways by autoradiographic survey of local metabolic rate with (14C)deoxyglucose.

An enzymatic preparation from human brain converts tryptamine to tryptoline (9H-1,2,3,4-tetrahydropyrido(3,4-b)indole) in the presence of 5-methyltetrahydrofolic acid. Similarly, N-methyltryptamine and 5-hydroxytryptamine yield 1-methyltryptoline and 5-hydroxytryptoline, respectively. Neither in vitro nor in vivo formation of these compounds by human tissues has been described.