Positive lifestyle behaviours and emotional health factors are associated with low back pain resilience.

PURPOSE: To evaluate the relationship between lifestyle behaviours, emotional health factors, and low back pain (LBP) resilience. METHODS: This retrospective longitudinal study utilised 1,065 twins with a recent history of LBP from the Washington State Twin Registry. A lifestyle behaviour score was built using variables of body mass index, physical activity engagement, sleep quality, smoking status, and alcohol consumption. An emotional health score was built using variables of the absence of depressed mood, perceived stress, and active coping. The main outcome was LBP resilience, assessed as recovery ("bouncing back"), and sustainability (maintaining high levels of function despite LBP). RESULTS: After adjusting for covariates, there was no relationship between the lifestyle behaviour score (OR 1.05, 95% CI 0.97-1.15, p = 0.218) and the emotional health score (OR 1.08, 95% CI 0.98-1.19, p = 0.142) with the likelihood of recovering from LBP. There was however, evidence of a positive association between the lifestyle behaviour score (ß 0.20, 95% CI 0.04-0.36, p = 0.013), the emotional health score (ß 0.22, 95% CI 0.00-0.43, p = 0.049), and greater levels of sustainability. These results were confirmed by a within-pair analysis (lifestyle behaviour score: ß 1.79, 95% CI 0.05-3.53, p = 0.043) and (emotional health score: ß 0.52, 95% CI 0.09-0.96, p = 0.021) adjusting for genetic and early shared environmental confounding. CONCLUSION: Findings from this study suggest that people who adopt optimal lifestyle behaviours and positive emotional factors are more likely to be resilient and maintain high levels of function despite suffering from LBP.

Neighborhood walkability moderates the association between low back pain and physical activity: A co-twin control study.

The aim of this study was to investigate whether neighborhood walkability moderates the association between low back pain (LBP) and physical activity (PA), using a co-twin design to control for genetics and shared environmental factors. A cross-sectional analysis was performed on 10,228 twins from the Washington State Twin Registry with available data on LBP from recruitment surveys between 2009 and 2013. LBP within the past 3months was our exposure variable. Our outcome variables were sufficient moderate or vigorous-intensity PA (MVPA, defined as at least 75min of vigorous-intensity PA, or 150min of moderate-intensity PA per week), and walking (≥150min per week). Neighborhood walkability, estimated using the commercially available Walk Score®, was our moderator variable. After controlling for the influence of genetics and shared environment, individuals reporting LBP were significantly less likely to engage in sufficient MVPA if they lived in a neighborhood with high walkability (OR=0.59, 95%CI: 0.36-0.96). There was no association between LBP and sufficient MVPA for individuals living in a neighborhood with low walkability (OR=1.27, 95%CI: 0.93-1.72), demonstrating that walkability is a significant moderator of the association between LBP and PA (interaction p=0.013). These findings were similar for the association between LBP and walking (high walkability OR=0.42, 95%CI: 0.22-0.78; low walkability OR=0.71, 95%CI: 0.46-1.12), although the interaction was not significant (p=0.700). Neighborhood walkability moderates the association between LBP and PA. Our results highlight the importance of targeting interventions promoting PA towards individuals with LBP living in a neighborhood with good walkable access to amenities.

Assessment of NMDA receptor activation in vivo by Fos induction after challenge with the direct NMDA agonist (tetrazol-5-yl)glycine: effects of clozapine and haloperidol.

Induction of Fos protein by the potent and direct NMDA agonist (tetrazol-5-yl)glycine (TZG) was examined in mice. Effects of antipsychotic drugs were assessed on this in vivo index of NMDA receptor activation. TZG induced the expression of Fos in a neuroanatomically selective manner, with the hippocampal formation showing the most robust response. In mice genetically altered to express low levels of the NR1 subunit of the NMDA receptor, TZG-induced Fos was reduced markedly in comparison to the wild type controls. TZG-induced Fos was also blocked by the selective NMDA antagonist MK-801. Pretreatment of mice with clozapine (3 and 10 mg/kg) reduced TZG-induced Fos in the hippocampal formation but not in other brain regions. Haloperidol at a dose of 0.5 mg/kg did not antagonize TZG induced Fos in any region. Haloperidol at a dose of 1.0 mg/kg did attenuate the induction of Fos by TZG in the hippocampus but not in other brain regions. The relatively high dose (1 mg/kg) of haloperidol required to block effects of TZG suggests that this action may not be related to the D(2) dopamine receptor-blocking properties, since maximal D(2) receptor blockade was probably achieved by the 0.5 mg/kg dose of haloperidol. The antidepressant drug imipramine (10 or 20 mg/kg) did not antagonize TZG induced Fos in any brain region. The data suggest that clozapine can reduce excessive activation of NMDA receptors by TZG administration in vivo at doses relevant to the drugs' actions in rodent models of antipsychotic activity. Whether or not this action of clozapine contributes to its therapeutic properties will require further study.

QUICKI does not accurately reflect changes in insulin sensitivity with exercise training.

A novel index of insulin sensitivity, the quick insulin sensitivity check index, termed QUICKI (1/[log (insulin) + log (glucose)]), was recently developed. We examined whether QUICKI accurately reflects changes in insulin sensitivity after exercise training, a perturbation known to improve insulin sensitivity. Sedentary, nondiabetic adults underwent a frequently sampled iv glucose tolerance test before and after 6 months of training. Insulin sensitivity was estimated from the glucose tolerance test using Bergman's minimal model (insulin sensitivity-minimal model), and QUICKI was calculated from basal insulin and glucose. Exercise increased (P = 0.003) insulin sensitivity-minimal model but did not change (P = 0.12) QUICKI. Before and after training, the rank-correlation between QUICKI and insulin sensitivity-minimal model was significant (r = 0.79, P = 0.0005; r = 0.56, P = 0.03, respectively). However, the rank-correlation between fasting insulin alone with insulin sensitivity-minimal model was as good (before training r = -0.77, P = 0.0009; after training r = -0.55, P = 0.03) as that between QUICKI and insulin sensitivity-minimal model. Fasting glucose was not related to insulin sensitivity-minimal model at either time. When difference scores (i.e. after pretraining values) were examined, neither QUICKI nor fasting insulin correlated with insulin sensitivity-minimal model (QUICKI vs. insulin sensitivity-minimal model r = 0.24, P = 0.39; fasting insulin vs. insulin sensitivity-minimal model r = -0.40, P = 0.14). We conclude that fasting insulin is equivalent to fasting insulin plus glucose (i.e. QUICKI) at estimating basal insulin sensitivity in nondiabetic adults. However, QUICKI does not accurately reflect exercise-induced changes in insulin sensitivity within individual subjects.

Dichloroacetate therapy attenuates the blood lactate response to submaximal exercise in patients with defects in mitochondrial energy metabolism.

We determined acute and chronic effects of dichloroacetate (DCA) on maximal (MAX) and submaximal (SUB) exercise responses in patients with abnormal mitochondrial energetics. Subjects (n = 9) completed a MAX treadmill bout 1 h after ingesting 25 mg/kg DCA or placebo (PL). A 15-min SUB bout was completed the next day while receiving the same treatment. After a 1-d washout, MAX and SUB were repeated while receiving the alternate treatment (acute). Gas exchange and heart rate were measured throughout all tests. Blood lactate (Bla) was measured 0, 3, and 10 min after MAX, and 5, 10, and 15 min during SUB. MAX and SUB were repeated after 3 months of daily DCA or PL. After a 2-wk washout, a final MAX and SUB were completed after 3 months of alternate treatment (chronic). Average Bla during SUB was lower (P < 0.05) during both acute (1.99 +/- 1.10 vs. 2.49 +/- 1.52 mmol/liter) and chronic (1.71 +/- 1.37 vs. 2.39 +/- 1.32 mmol/liter) DCA vs. PL despite similar exercise intensities between conditions ( approximately 75 and 70% maximal exercise capacity during acute and chronic treatment). Thus, although DCA does not alter MAX responses, acute and chronic DCA attenuate the Bla response to moderate exercise in patients with abnormal mitochondrial energetics.

Beta-adrenergic receptor binding in frontal cortex from suicide victims.

Beta-adrenergic binding in frontal cortex samples from suicide victims has been reported to be increased, unaltered, and decreased compared to matched controls. Subject's diagnoses and drug exposures in these studies were not equivalently documented and were possibly different. In the present study, diagnostic and symptomatic information was systematically collected from family members of 15 subjects committing suicide and 15 matched controls using standardized interview techniques. The goal was to test the hypothesis that alterations in beta-adrenergic binding were more likely to be found in subjects with evidence of depressive disorders. [125I]pindolol binding in frontal cortex was found to be significantly lower in the group committing suicide compared to the matched controls (21.1 +/- 1.1 fmol/mg protein vs. 24.8 +/- 0.8 fmol/mg protein, p < .02). However, no diagnostic subgroup among the suicide victims appeared distinct.

Beta-adrenergic receptor binding in human and rat hypothalamus.

Quantitative autoradiographic analysis of beta-adrenergic binding sites was conducted in human postmortem hypothalamus using the radioligand 125I-pindolol. The focus was on the hypothalamic nuclei most clearly involved in corticotropin-releasing hormone (CRH) release, the PVN and SON. For comparison, the distribution of hypothalamic beta-adrenergic receptors was evaluated in the rat. A high level of beta-adrenergic receptor binding was found in the human paraventricular nucleus (PVN) and supraoptic nucleus (SON), but not in the rat. The majority of the beta-adrenergic receptors found in the human hypothalamus were of the beta 2-subtype. In contrast, in the rat hypothalamus, the majority of receptors were of the beta 1-subtype. These results show that the anatomical loci exist for direct beta-adrenergic influence on hypothalamic neuroendocrine function in the human and that the topography of beta-adrenergic receptors is markedly different in the rat and human hypothalamus.

Olanzapine increases allopregnanolone in the rat cerebral cortex.

BACKGROUND: The neurosteroid allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one) has anxiolytic and anticonvulsant properties, potentiating GABA(A) receptor chloride channel function with 20-fold higher potency than benzodiazepines. Behavioral studies demonstrate that olanzapine has anxiolyticlike properties in animals, but the mechanism responsible for these effects is not clear. We examined the effect of acute olanzapine administration on cerebral cortical allopregnanolone and its relationship to serum progesterone and corticosterone levels in rats. METHODS: Male Sprague-Dawley rats were habituated to intraperitoneal (IP) saline injection for 5 days. On the day of the experiment, rats were injected with olanzapine (0, 2.5, 5.0, or 10.0 mg/kg IP, 10-11 rats per condition). Rats were sacrificed 1 hour later, and cerebral cortical allopregnanolone levels and serum progesterone and corticosterone levels were measured by radioimmunoassay. RESULTS: Olanzapine increases cerebral cortical allopregnanolone up to fourfold, depending on dose. Positive correlations were observed between cerebral cortical allopregnanolone and serum progesterone levels and between cerebral cortical allopregnanolone and serum corticosterone levels. CONCLUSIONS: Olanzapine-induced increases in the potent GABA(A) receptor modulator allopregnanolone may alter GABAergic neurotransmission, possibly contributing to antipsychotic efficacy. If allopregnanolone alterations are linked to psychotic symptom relief, neurosteroids may represent molecules for pharmacologic intervention.

Effects of ketamine, MK-801, and amphetamine on regional brain 2-deoxyglucose uptake in freely moving mice.

Although the pathophysiology of schizophrenia remains unclear, behavioral effects in humans induced by N-methyl-D-aspartate (NMDA) antagonists, such as ketamine, provide direction for formulating new pharmacologic models of the illness. The purpose of the present study was to clarify the roles of NMDA receptor antagonism, as well as dopamine-releasing properties of ketamine, in regional brain metabolic activity and behavioral responses in mice. The effects of acute administration of ketamine (30 mg/kg, i.p.) were compared with those of the more selective non-competitive NMDA antagonist MK-801 (0.3 and 0.5 mg/kg, i.p.), and amphetamine (4 mg/kg, i.p.) on regional brain [14C]-2-deoxyglucose (2-DG) uptake, by using a high resolution autoradiographic technique in the freely moving mice. Both ketamine and MK-801 induced substantial and similar neuroanatomically selective alterations in regional 2-DG uptake. Remarkable increases in 2-DG uptake in response to the NMDA antagonists were seen in limbic cortical regions, hippocampal formation, nucleus accumbens, select thalamic nuclei, and basolateral amygdala. The behavior of mice given amphetamine was similar to that of mice given MK-801. However, the brain activity patterns induced by amphetamine were distinctly different from those observed after ketamine and MK-801 treatment. These results suggest that generalized behavioral activation and increased dopamine release are insufficient to account for the ketamine-induced alterations in regional brain metabolism, and that the effects of ketamine on 2-DG uptake are likely related to a reduction in NMDA receptor function. The data also suggest that ketamine-induced changes in 2-DG uptake may provide a useful paradigm for translational research to better understand the pathophysiology of schizophrenia.

Brain activity patterns in flying, echolocating bats (Pteronotus parnellii): assessment by high resolution autoradiographic imaging with [3H]2-deoxyglucose.

Brain activity patterns during echolocation and flight were assessed in mustached bats (Pteronotus parnellii parnellii). Bats were injected intraperitoneally with [3H]2-deoxyglucose and restrained in a foam holder or allowed to fly for 20 min. Under resting conditions, low levels of [3H]2-deoxyglucose uptake were observed throughout the forebrain but relatively high uptake was found in brainstem auditory and vestibular centers. In flying, echolocating bats, marked increases in regional [3H]2-deoxyglucose uptake were apparent. All structures of the classical ascending auditory pathway were intensely labeled in autoradiograms. Other brain regions that exhibited high [3H]2-deoxyglucose uptake in flying bats included the cingulate cortex, stratum lacunosum-moleculare of the hippocampus, thalamus, caudate-putamen, superior colliculus, pontine reticular formation, nucleus ambiguus, parts of the midbrain central gray, and cerebellum. In the cerebellum, the most prominent increase in [3H]2-deoxyglucose uptake was found in discrete patches of the granule cell layer. The results provide the first overview of brain activity patterns during echolocation and flight in bats. In addition, uptake of [14C]fluorodeoxyglucose was used to compare brain activity patterns in flying bats to bats that were imaging their environment via biosonar while hanging in a wire cage. The echolocating-not-flying bats emitted 6931 +/- 1226 pulses in 20 min compared to 8972 +/- 1273 pulses in 20 min for flying bats. The uptake of the metabolic marker was significantly more in the flying bats compared to the emitting-not-flying bats in the medial geniculate, superior colliculus, auditory cortex, cingulate cortex and thalamus. In the nucleus ambiguus, cochlear nucleus, and inferior colliculus, uptake was similar for the flying and emitting-not-flying bats. These results suggest that the high metabolic activity observed in forebrain auditory regions of flying bats is related in part to neural processes that involve sensory motor integration during flight and not simply the perception of acoustic information.

Topography of basal glucose utilization in the hippocampus determined with [1-14C]glucose and [6-14C]glucose.

The activity of the pentose phosphate shunt was assessed under basal conditions in subregions of the hippocampus by measuring the uptake and retention of [1-14C]glucose and [6-14C]glucose and their 14C-labelled metabolites. The relative and absolute retention of carbon-14 from each of the two compounds was nearly identical in all regions examined. For each compound, the highest accumulation of 14C occurred in the granule cell layer of the dentate gyrus and in the pyramidal cell layer. Relatively high retention of radioactivity was also found in the molecular layer of dentate gyrus and in the stratum lacunosum-molecular. The stratum radiatum and stratum oriens contained the lowest levels of radioactivity among hippocampal regions. The equal retention of radioactivity from [1-14C]glucose and [6-14C]glucose implies that pentose phosphate shunt activity is very low throughout the hippocampus under the conditions of this study. The uptake and retention of radioactivity was evaluated in different hippocampal regions 10 or 30 min following intravenous injection of [1-14C]glucose. Although there was significantly more radioactivity at 30 min than at 10 min, the same topographic pattern of radioactivity within the hippocampus was observed in rats after both survival periods, indicating that an equal fraction of the [1-14C]glucose utilized in different hippocampal regions is oxidized to 14CO2 under these conditions. Most regions of high glucose utilization in the hippocampus determined with [1-14C]glucose and [6-14C]glucose correspond to regions of intense histochemical staining for cytochrome oxidase reported in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Topographical assessment of accumulated radioactivity from [14C]2-deoxyglucose and [6(-14C)]glucose in rat forebrain at different survival periods.

The uptake and retention of radioactivity was measured in discrete areas of rat brain at different times after i.v. injection of [14C]2-deoxyglucose or [6(-14)C]glucose, in unrestrained rats. In most brain regions, the accumulation of radioactivity from the two compounds was similar when a 30-min survival period for [6(-14)C]glucose was compared to a 45-min survival period for [14C]2-deoxyglucose. However, at those times, autoradiographic images of the hippocampus and piriform cortex appeared distinctly different for [14C]2-deoxyglucose and [6(-14)C]glucose. Relatively more radioactivity accumulated from [14C]2-deoxyglucose, compared to [14C]glucose, in the stratum lacunosum-moleculare of the hippocampus and in layer 4 of the isocortex. In contrast, relatively more radioactivity accumulated from [6(-14)C]glucose, compared to [14C]2-deoxyglucose, in the molecular and granule cell layers of the dentate gyrus, the CA1 pyramidal cell layer of the hippocampus, and in layer 2 of the piriform cortex. When rats were killed 5 min after injection of [6(-14)C]glucose, the relative neuroanatomical distribution of radioactivity was similar to the 30-min survival period, except in layer 4 of the isocortex, where relatively more radioactivity was present at the early time. When rats were killed 5 min after injection of [14C]2-deoxyglucose, in 20 of 24 brain regions examined, the absolute and relative amounts of accumulated radioactivity were similar when compared to that of the 45-min survival period. In contrast, the absolute and relative amounts of radioactivity were significantly greater for the 5-min compared to the 45-min survival period, in the CA1 pyramidal cell field, dentate gyrus, and layer 2 of the piriform cortex. For those regions, the appearance of autoradiograms prepared from rats killed 5 min after administration of [14C]2-deoxyglucose is remarkably similar to the appearance of autoradiograms prepared from rats killed 5 or 30 min after injection of [6(-14)C]glucose. Possible mechanisms are discussed to explain the observed differences in the accumulation of radioactivity in discrete brain regions after injection of [6(-14)C]glucose and [14C]2-deoxyglucose at the different survival times examined.

High activity neurons in the reticular formation of the medulla oblongata: a high-resolution autoradiographic 2-deoxyglucose study.

Accumulation of radioactivity in the medulla oblongata of the rat was assessed with high resolution autoradiography after injection of [3H]2-deoxyglucose or [14C]2-deoxyglucose. The autoradiographic approach employed allowed analysis at the cellular level. A salient feature of autoradiograms was the presence of foci of very high silver grain density in the reticular formation. These heavily labeled foci were shown to be associated with neurons by combined Acridine Orange staining and autoradiography. The high activity neurons in the ventral lateral medulla were predominantly located in the caudal portion of the paragigantocellular reticular nucleus. In addition, a group of high activity neurons was present in the dorsal reticular formation. The potential involvement of the high activity neurons in cardiovascular and respiratory regulation is discussed. In dry-mount autoradiograms produced after injection of [3H]2-deoxyglucose, certain small cells, presumably glial cells, were observed throughout the brainstem to accumulate radioactivity to a greater extent than the surrounding tissue. High activity neurons and high activity glial cells were observed for 5 min and 45 min survival intervals after intravenous injection of [3H]2-deoxyglucose. The similar appearance of autoradiograms at 5 min and 45 min after injection of [3H]2-deoxyglucose indicates that the utility of a 5-min survival period deserves further evaluation for assessment of functional activity patterns in brain.

Ontogeny of D1A and D2 dopamine receptor subtypes in rat brain using in situ hybridization and receptor binding.

The prenatal and postnatal ontogeny of D1A and D2 dopamine receptors was assessed by in situ hybridization of messenger RNAs encoding the receptors and by radioligand binding autoradiography. On gestational day 14, signals for D1A and D2 dopamine receptor messages were observed in selected regions in ventricular and subventricular zones which contain dividing neuroblasts, and in intermediate zones that contain maturing and migrating neurons. Specifically, D1A and D2 dopamine receptor message was observed in the developing caudate-putamen, olfactory tubercle, and frontal, cingulate, parietal and insular cortices. Additionally, D1A dopamine receptor messenger RNA was found in the developing epithalamus, thalamus, hypothalamus, pons, spinal cord and neural retina; D2 dopamine receptor messenger RNA was also observed in the mesencephalic dopaminergic nuclear complex. Gene expression of D1A and D2 dopamine receptor subtypes in specific cells as they differentiate precedes dopamine innervation and implies that receptor expression is an intrinsic property of these neurons. The early expression of dopamine receptor messenger RNA suggests a regulatory role for these receptors in brain development. While the signal for both messages increased in the intermediate zones on gestational day 16, it decreased in the ventricular and subventricular zones, and was no longer apparent in these zones by gestational day 18. By gestational day 18, abundant D1A or D2 dopamine receptor messenger RNA was observed in cell groups similar in location to those observed in the adult brain. On gestational day 18, D1A dopamine receptor message was noted in the neural retina, anterior olfactory nucleus, the insular, prefrontal, frontal, cingulate, parietal and retrosplenial cortices, the olfactory tubercle, caudate-putamen, lateral habenula, dorsolateral geniculate nucleus, ventrolateral and mediolateral thalamic nuclei, and the suprachiasmatic and ventromedial nuclei of the hypothalamus. D2 dopamine receptor message was observed on gestational day 18 in the insular, prefrontal, frontal and cingulate cortices, the olfactory tubercle, caudate-putamen, ventral tegmental area, substantia nigra, and the intermediate lobe of the pituitary. At birth, expression of messenger RNA for both dopamine receptor subtypes in the striatum approximated that seen in mature rats. In contrast, D1A and D2 receptor binding, measured with [3H]SCH-23390 and [3H]raclopride, respectively, was low at birth and progressively increased to reach adult levels between days 14 and 21. The in situ hybridization data showing early prenatal expression of messenger RNA for the D1A and D2 dopamine receptors are consistent with the hypothesis that these receptors have a regulatory role in neuronal development.(ABSTRACT TRUNCATED AT 400 WORDS)

Distribution of [3H]zolpidem binding sites in relation to messenger RNA encoding the alpha 1, beta 2 and gamma 2 subunits of GABAA receptors in rat brain.

Localization of the messenger RNAs that encode the alpha 1, beta 2 and gamma 2 subunits of GABAA showed a distinct topographic pattern in rat brain which corresponded with [3H]zolpidem binding in most brain regions. The close topographic correspondence between the specific receptor subunits examined and the distribution of [3H]zolpidem binding sites provides support for the hypothesis that this benzodiazepine type 1 selective ligand binds to a GABAA receptor that consists of alpha 1, beta 2 and gamma 2 subunits in the rat brain. Brain regions with relatively high densities of alpha 1, beta 2 and gamma 2 subunits of GABAA and [3H]zolpidem binding included olfactory bulb, medial septum, ventral pallidum, diagonal band, inferior colliculus, substantia nigra pars reticulata and specific layers of the cortex. Two areas with low [3H]zolpidem binding and a virtual absence of these GABAA receptor subunit messenger RNAs were the lateral septum and the striatum. In contrast to the discrete pattern observed for alpha 1 and beta 2 subunit messenger RNAs, the gamma 2 subunit messenger RNA was distributed more diffusely in brain. Only the hippocampus, layer 2 of the piriform cortex and the cerebellum showed a strong concentration of the gamma 2 subunit messenger RNA. It was determined with a polymerase chain reaction assay that both long and short variants of the gamma 2 subunit messenger RNAs were present within several of the brain sites selected for examination. Sites with high densities of [3H]zolpidem binding sites had a greater relative abundance of the gamma 2 long splice variant, compared to the gamma 2 short variant. There were some regions that expressed high levels of alpha 1, beta 2 and gamma 2S subunit messenger RNAs but low [3H]zolpidem binding, suggesting that gamma 2 splice variant expression may modulate high-affinity [3H]zolpidem binding. To determine relationships between in vitro [3H]zolpidem binding and functional sensitivity in vivo, interactions between zolpidem and GABA were assessed in brain regions that contained high and low densities of [3H]zolpidem binding sites. In the medial septum, a brain region with a high concentration of [3H]zolpidem binding sites, iontophoretic application of zolpidem enhanced the inhibitory effect of GABA responses on 70% of the neurons examined. In the lateral septum, which contains very low densities of [3H]zolpidem binding sites, neurons were not sensitive to zolpidem enhancement of GABA-induced inhibition. These electrophysiological results demonstrate a correspondence between the regional distribution of [3H]zolpidem binding in vitro and functional sensitivity to the drug in vivo.

High resolution autoradiographic determination of the topographic distribution of radioactivity in the hippocampal formation after injection of [1-14C]glucose or 2-deoxy[14C]glucose.

Using high resolution autoradiography, the accumulation of radioactivity after intravenous injection of [1-14C]glucose was measured in the corpus callosum, hippocampus, dorsal hippocampal commissure, somatosensory cortex, inferior colliculus and pontine periaqueductal grey. Autoradiograms were prepared by thaw-mounting 4 micron frozen sections on nuclear emulsion-coated slides, and were evaluated quantitatively with a computer-assisted video system for automated counting of silver grains. In all brain regions examined, silver grain densities were greater in rats killed 30 min after injection of [1-14C]glucose compared to rats killed 10 min after injection. After intravenous injection of [1-14C]glucose or 2-deoxy[14C]glucose, the relative uptake and retention of radioactivity in different hippocampal subregions was compared. Striking differences were found in the hippocampus between 2-deoxy[14C]glucose and [1-14C]glucose autoradiograms. After injection of 2-deoxy[14C]glucose, there were large variations in the uptake and retention of radioactivity among different pyramidal cell fields. The CA 3 pyramidal cell field retained considerably more radioactivity than other pyramidal cell fields after injection of 2-deoxy[14C]glucose, while after injection of [1-14C]glucose, the retention of radioactivity was similar in all pyramidal cell fields. After [1-14C]glucose injection, the dentate gyrus contained relatively high levels of radioactivity and more 14C accumulated in the granular layer, compared to the molecular layer. In contrast, after 2-deoxy[14C]glucose injection, there was uniformly less radioactivity throughout the dentate gyrus when compared to rats injected with [1-14C]glucose and there was no preferential accumulation of 2-deoxy[14C]glucose in the granular layer compared to the molecular layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Delta 9-tetrahydrocannabinol sensitization of the rat brain to direct cholinergic stimulation.

In an attempt to define the nature of the involvement of delta 9-tetrahydrocannabinol (THC) with central cholinergic neurotransmission, the effects of THC on direct cholinergic stimulation of the rat brain were investigated. THC, in doses of 3 mg/kg and 6 mg/kg, administered intraperitoneally (i.p.), potentiated the effects of carbachol injection into the lateral septal nucleus, as manifested by enhancement of the drinking response elicited by the septal carbachol injection and by potentiation of the tendency of this carbachol injection to induce abnormal motor responses. Although atropine (10 mg/kg, i.p.) completely blocked the carbachol induced drinking, the atropine did not completely block the drinking response when THC was given with carbachol. The results indicate an apparent sensitization, by THC, of a limbic cholinergic system.

Enhanced ultrasonic vocalization and Fos protein expression following ethanol withdrawal: effects of flumazenil.

RATIONALE: Administration of flumazenil, a benzodiazepine (BZD) antagonist, has therapeutic efficacy against some anxiogenic effects of ethanol withdrawal. This observation has led to the suggestion that anxiety associated with ethanol withdrawal is related to release in brain of an endogenous BZD inverse agonist. OBJECTIVE: The present studies further tested this hypothesis by assessing the effect of flumazenil on withdrawal-induced changes in a behavioral task and on the expression of the neuronal protein, Fos. METHODS: Male Sprague-Dawley rats were withdrawn from a chronic ethanol regimen and tested, with or without flumazenil pretreatment, for either ultrasonic vocalization in response to air puff or for the induction of Fos protein-like immunoreactivity (Fos-LI) in brain. In addition, flumazenil effects on Fos-LI were measured in a group of animals treated with the BZD inverse agonist DMCM (0.75 and 1.0 mg/kg). RESULTS: Flumazenil (5.0 mg/kg) significantly reduced the number of ultrasonic vocalizations observed following withdrawal from chronic ethanol. In contrast, flumazenil (5.0 mg/kg), given either 14 h before withdrawal from chronic ethanol, or during hours 3 and 5 following withdrawal, did not attenuate the effects of withdrawal on Fos-LI. Subsequent testing with DMCM confirmed that a benzodiazepine inverse agonist can induce Fos-LI in most of the same brain regions as observed following ethanol withdrawal, and that this change in Fos protein can be attenuated by pretreatment with flumazenil (5.0 mg/kg). CONCLUSIONS: Overall, these results demonstrate that specific behavioral indices of anxiety, but not measures of Fos-LI, support the contribution of an endogenous BZD inverse agonist in the ethanol withdrawal syndrome.

High resolution autoradiography at the regional topographic level with [14C]2-deoxyglucose and [3H]2-deoxyglucose.

After injection of 2-deoxyglucose (2-DG) labeled with tritium or carbon-14, autoradiograms were produced by thaw-mounting 4 micron frozen sections of rat brains on nuclear emulsion-coated slides. The results show that the distribution of radioactivity among different brain regions was similar and that the resolution at the regional topographical level was virtually identical for both compounds. The resolution obtained with the thaw-mounting of thin frozen sections onto nuclear emulsion was considerably greater than the resolution demonstrated in published results in the literature, when carbon-14 or tritium-labeled 2-deoxyglucose were used with 20 micron frozen sections and X-ray film or tritium-sensitive film. The results indicate that section thickness, detection medium and intimacy of contact between section and photographic emulsion influence resolution. At the regional level, the detection medium apparently influences resolution to a greater extent than the energy differences of the beta particles emitted from 14C or 3H. Although diffusion of radiolabeled 2-deoxyglucose and metabolites during the thaw-mounting process precludes single cell resolution of these autoradiograms, the improvement of visualizing regional topographic detail demonstrates that the described technique is a valuable approach with which to study regional 2-DG uptake.

Target neurons for [3H]corticosterone in the rat spinal cord.

Rats were injected with [3H]corticosterone and their spinal cords processed for autoradiography. Nuclear concentration of the tritiated steroid was observed in motor neurons in cervical, thoracic, lumbar, and sacral regions. Nuclear concentrations of [3H]corticosterone was also observed in certain neurons of laminae VII and III in all levels of the spinal cord. Injection of unlabeled corticosterone 5 min before the [3H]corticosterone injection abolished the nuclear concentration of the adrenal steroid. These results provide the morphological basis for a direct genomic action of corticosterone in spinal motor neurons and in neurons of laminae III and VII.