Investigation of intrathecal transport of NPT002, a prospective therapeutic based on phage M13, in nonhuman primates.

Presently, there are no effective treatments for conditions characterized by protein misfolding, such as Alzheimer's, Parkinson's, and other diseases involving CNS. Since misfolding occurs at the earliest stage of the disease, it is likely to be involved in subsequent pathological developments. It has been found that NPT002 (bacteriophage M13) directly dissociates aggregates of misfolded proteins that form amyloid, including amyloid-ß, tau and α-synuclein. For CNS applications, NPT002 requires delivery to the brain parenchyma, the target tissue. NPT002 is an elongated ~950 nm particle that cannot penetrate into the brain from the blood. Furthermore, phage particles, due to their size, cannot be effectively transported in vivo by diffusion. Considering the physiology of the leptomeningeal space, intrathecal administration appears to be a promising convection-driven avenue for NPT002 delivery. In this paper, we use positron emission tomography to investigate the transport of NPT002 in Macaca fascicularis. The data suggest that approximately 50 % of the administered dose can reach the cerebral leptomeningeal space after a single lumbar intrathecal injection. A biologically significant fraction of the phage then enters the brain, resulting in potentially therapeutic cortical and subcortical exposure.

Holeboard discrimination learning in mice.

We have adapted to mice a holeboard-learning task, which allows simultaneous assessment of spatial working and reference-memory performance. The holeboard apparatus consists of an open-field chamber with a 16-hole floor insert. Across trials, animals have to learn that the same four holes of 16 are always baited. Here, we show that C57BL/6 mice readily acquire this task within 4 days when submitted to six trials per day or within 8 days when submitted to only four trials per day. We also show that C57BL/6, Swiss-Webster, CD-1 and DBA/2 mice acquire this task similarly, despite the fact that some differences could be observed in measures of exploratory activity during habituation and training. Moreover, the muscarinic antagonist scopolamine disrupts learning at doses of 0.1 and 1.0 mg/kg, although the highest dose appeared to have side-effects. Lastly, we found that amyloid precursor protein transgenic mice have a selective disruption in their working-memory performance only during reversal training (i.e. after a change in the configuration of the baited holes). Overall, our data indicate that this spatial learning task is well adapted to mice and will be useful to characterize spatial memory in various genetic or pharmacological mouse models.

A novel augmentation strategy for treating resistant major depression.

OBJECTIVE: Treatment-resistant depression is a significant public health concern; drug switching or augmentation often produce limited results. The authors hypothesized that fluoxetine could be augmented with olanzapine to successfully treat resistant depression. METHOD: An 8-week double-blind study was conducted with 28 patients who were diagnosed with recurrent, nonbipolar, treatment-resistant depression without psychotic features. Subjects were randomly assigned to one of three groups: olanzapine plus placebo, fluoxetine plus placebo, or olanzapine plus fluoxetine. RESULTS: Fluoxetine monotherapy produced minimal improvement on various scales that rate severity of depression. The benefits of olanzapine monotherapy were modest. Olanzapine plus fluoxetine produced significantly greater improvement than either monotherapy on one measure and significantly greater improvement than olanzapine monotherapy on the other measures after 1 week. There were no significant differences between treatment groups on extrapyramidal measures nor significant adverse drug interactions. CONCLUSIONS: Olanzapine plus fluoxetine demonstrated superior efficacy for treating resistant depression compared to either agent alone.

Phototransduction in transgenic mice after targeted deletion of the rod transducin alpha -subunit.

Retinal photoreceptors use the heterotrimeric G protein transducin to couple rhodopsin to a biochemical cascade that underlies the electrical photoresponse. Several isoforms of each transducin subunit are present in the retina. Although rods and cones seem to contain distinct transducin subunits, it is not known whether phototransduction in a given cell type depends strictly on a single form of each subunit. To approach this question, we have deleted the gene for the rod transducin alpha-subunit in mice. In hemizygous knockout mice, there was a small reduction in retinal transducin alpha-subunit content but retinal morphology and the physiology of single rods were largely normal. In homozygous knockout mice, a mild retinal degeneration occurred with age. Rod-driven components were absent from the electroretinogram, whereas cone-driven components were retained. Every photoreceptor examined by single-cell recording failed to respond to flashes, with one exception. The solitary responsive cell was insensitive, as expected for a cone, but had a rod-like spectral sensitivity and flash response kinetics that were slow, even for rods. These results indicate that most if not all rods use a single transducin type in phototransduction.

Olanzapine treatment of psychotic and behavioral symptoms in patients with Alzheimer disease in nursing care facilities: a double-blind, randomized, placebo-controlled trial. The HGEU Study Group.

BACKGROUND: Patients with Alzheimer disease (AD) commonly exhibit psychosis and behavioral disturbances that impair patient functioning, create caregiver distress, and lead to institutionalization. This study was conducted to assess the efficacy and safety of olanzapine in treating psychosis and/or agitation/aggression in patients with AD. METHODS: A multicenter, double-blind, placebo-controlled, 6-week study was conducted in 206 elderly US nursing home residents with AD who exhibited psychotic and/or behavioral symptoms. Patients were randomly assigned to placebo or a fixed dose of 5, 10, or 15 mg/d of olanzapine. The primary efficacy measure was the sum of the Agitation/Aggression, Hallucinations, and Delusions items (Core Total) of the Neuropsychiatric Inventory-Nursing Home version. RESULTS: Low-dose olanzapine (5 and 10 mg/d) produced significant improvement compared with placebo on the Core Total (-7.6 vs -3.7 [P<.001] and -6.1 vs -3. 7 [P =.006], respectively). Core Total improvement with olanzapine, 15 mg/d, was not significantly greater than placebo. The Occupational Disruptiveness score, reflecting the impact of patients' psychosis and behavioral disturbances on the caregiver, was significantly reduced in the 5-mg/d olanzapine group compared with placebo (-2.7 vs -1.5; P =.008). Somnolence was significantly more common among patients receiving olanzapine (25.0%-35.8%), and gait disturbance occurred in those receiving 5 or 15 mg/d (19.6% and 17.0%, respectively). No significant cognitive impairment, increase in extrapyramidal symptoms, or central anticholinergic effects were found at any olanzapine dose relative to placebo. CONCLUSION: Low-dose olanzapine (5 and 10 mg/d) was significantly superior to placebo and well tolerated in treating agitation/aggression and psychosis in this population of patients with AD.

SW.B6-Soa(b) nontaster congenic strains completed and a sucrose octaacetate congenic quartet tested with other bitters.

Ten SW.B6 SOA nontaster strains congenic with the SWR/J SOA taster inbred strain were bred via repeated backcross-intercross cycles, with selection for nontasting in each cycle. Preference ratio distributions and phenotypic proportions across cycles at 0.1 mM SOA were consistent with monogenic predictions. The SW.B6 mice completed a congenic quartet with the SWR/J, B6.SW SOA taster and C57BL/6J SOA nontaster strains. The Soa locus controlled avoidance differences within the quartet for SOA, raffinose undecaacetate, glucose pentaacetate and brucine. Background genes not linked to Soa controlled avoidance differences for L-phenylalanine and ethanol. Avoidance of bitter picric acid was influenced by the Soa locus, but avoidance of acetic acid was not. The quartet pattern for quinine HCl was unclear, with indications of both Soa and background effects. Two forms of ribose tetraacetate yielded different patterns. Avoidance differences controlled by the Soa locus were found for the pyranose form; however, all four strains avoided the furanose form. The pleiotropic effects of Soa allele substitution within the quartet were limited to a subset of bitter compounds.

Transduction of bitter and sweet taste by gustducin.

Several lines of evidence suggest that both sweet and bitter tastes are transduced via receptors coupled to heterotrimeric guanine-nucleotide-binding proteins (G proteins). Gustducin is a taste receptor cell (TRC)-specific G protein that is closely related to the transducins. Gustducin and rod transducin, which is also expressed in TRCs, have been proposed to couple bitter-responsive receptors to TRC-specific phosphodiesterases to regulate intracellular cyclic nucleotides. Here we investigate gustducin's role in taste transduction by generating and characterizing mice deficient in the gustducin alpha-subunit (alpha-gustducin). As predicted, the mutant mice showed reduced behavioural and electrophysiological responses to bitter compounds, whereas they were indistinguishable from wild-type controls in their responses to salty and sour stimuli. Unexpectedly, mutant mice also exhibited reduced behavioural and electrophysiological responses to sweet compounds. Our results suggest that gustducin is a principal mediator of both bitter and sweet signal transduction.

Sodium intake linked to amiloride-sensitive gustatory transduction in C57BL/6J and 129/J mice.

Mice of 129/J and C57BL/6J inbred strains received two-bottle, 48-h preference tests of NaCl solutions vs. distilled water. 129/J mice exhibited a greater preference for 0.08 M NaCl than did C57BL/6J mice. To determine if this strain difference was mediated by taste, the integrated neural responses of the chorda tympani nerve to a concentration range of NaCl and KCl were examined. Gustatory neural responses to NaCl were similar for 129/J and C57BL/6J mice. However, lingual application of 0.5 mM amiloride hydrochloride significantly suppressed chorda tympani responses to a range of NaCl concentrations in C57BL/6J mice but did not do so consistently in 129/J mice. Amiloride failed to significantly suppress responses to a range of KCl concentrations in both mouse strains. The results suggest that for 129/J mice, sodium reception and transduction are primarily amiloride insensitive, whereas for C57BL/6J mice, both amiloride-sensitive and amiloride-insensitive components are present. The strain difference in NaCl intake may be mediated, in part, through gustatory mechanisms, with reduced preference for NaCl influenced by amiloride-sensitive sodium transduction mechanisms.

Salt appetite induced by DOCA treatment or adrenalectomy in rats: analysis of ingestive behavior.

A detailed description of the increased intake of 0.5 M NaCl solution by rats after systemic treatment with desoxycorticosterone acetate (DOCA) or after adrenalectomy was obtained by measuring feeding and drinking activity every 6 s for 23 h. In both models of salt appetite, the induced increase in saline intake occurred mostly at night and in close temporal association with bouts of eating and water drinking rather than in isolation. Consequently, there was no significant change in the total number of ingestive episodes, despite the substantial increase in the number of saline bouts. Saline drinking was in small draughts that usually were preceded by food bouts and followed promptly by water bouts. These and other observations indicate that under standard maintenance conditions of ad lib access to food and fluids, adrenalectomy and DOCA treatment each produce a relatively weak stimulus of salt appetite, and large daily intakes accrue because the animals do not remain satiated and the appetite recurs repeatedly.

A system for studying the microstructure of ingestive behavior in mice.

A system for long-term monitoring of mouse eating and drinking behavior with 6-s resolution is described. The apparatus utilizes infrared beams to monitor activity at a single feeding port and electronic contact detector circuitry to record individual licks at two drinking ports. Eight SWR/J mice were monitored using this system and data from the last day of testing with food and water were analyzed. Mice ate an average of 4.54 +/- 0.40 g of powdered food and drank an average of 5.81 +/- 0.65 ml of water. Mice had an average of 36.25 +/- 3.96 food bouts and 32.25 +/- 7.56 water bouts lasting 3.00 +/- 0.48 and 0.88 +/- 0.35 min, respectively. Information regarding the temporal association between eating and drinking and the circadian patterns of ingestion was provided, utilizing customized software that augments the system. Important implications for the use of mice in ingestion pattern research are discussed.

Thirst and salt appetite induced by hypovolemia in rats: analysis of drinking behavior.

A detailed description of the increased intake of water and 0.5 M NaCl solution by rats after colloid-induced hypovolemia was obtained by measuring drinking activity every 6 s for 23 h. After an initial phase of largely single-bout water drinking that reflected hypovolemic thirst, there was a marked increase in saline drinking in multiple-bout episodes. This salt appetite developed while rats were volume depleted but persisted for hours even after the plasma volume deficits were repaired. Their drinking episodes then seemed to reflect osmoregulation, since cumulative intakes of water and saline were in appropriate proportions to produce a near-isotonic NaCl solution. Remarkably, rats concocted a 1% NaCl solution within 29% of the drinking episodes, by alternating intakes of water and saline every 30-90 s. This alternation was too rapid to allow significant absorption of ingested fluids from the intestines and changes in plasma osmolality, and thereby to permit central osmoreceptors to influence ongoing consumption. Instead, we propose that, in these episodes, rats are guided by gustatory receptors to obtain the desired NaCl in a palatable solution.

Ingestion patterns of food, water, saccharin and sucrose in streptozotocin-induced diabetic rats.

Changes in preference for sweet tasting solutions have previously been reported in diabetic rats. The present study was designed to use detailed analyses of drinking patterns to investigate changes in sweet taste perception in rats made diabetic with a streptozotocin (SZ) injection and tested with saccharin and a broad range of sucrose concentrations. Although meal patterns in diabetic rats have been studied extensively, drinking patterns and their relation to meal patterns have not been described. A second goal of this research was to use the detailed patterns of eating and drinking of the diabetic rat in an effort to understand the resulting hyperphagia. Rats were given IP injection of SZ or saline. Following the SZ injection, the rats showed marked increase in blood glucose levels, an increase in food and fluid intake and they failed to gain weight. The SZ-injected rats showed a loss of preference for saccharin and for high concentrations of sucrose. Patterns of sucrose ingestion that are correlated with taste perception were distorted in the diabetic rats. The detailed pattern analysis of eating showed that the diabetic-induced hyperphagia resulted from a marked increase in length of eating bouts. The increase in fluid intake in the diabetic rats resulted from both an increase in frequency and length of drinking bouts. Circadian patterns of both food and fluid ingestion were maintained in the diabetic rats.

The B6.SW bilineal congenic sucrose octaacetate (SOA)-taster mice.

SWR/J inbred mice (Tasters) reliably avoid, whereas C57BL/6J inbred mice (Nontasters) are indifferent to, sucrose octaacetate (SOA) at certain concentrations. From these strains we have developed a set of bilineal congenic Taster mice. Approximately 4000 mice, from 2 isogenic and 12 segregating generations, were tested in a program designed to evaluate genetic models for SOA tasting during development of congenic strains. The criterion phenotype was avoidance or nonavoidance in preference tests of the bitter tastant SOA at concentrations of 10(-4) and 10(-5) M. Across the 12 segregating generations, the results were consistent with Mendelian expectations for a single autosomal locus with complete dominance of the Taster phenotype. The breeding program produced 12 replicate B6.SW lines containing the taster allele on the B6-Nontaster genomic background. The congenic Taster mice may facilitate a functional analysis of the sense of taste.

Sucrose octaacetate tasting in a heterogeneous population of CFW mice.

Three experiments investigated the genetic underpinnings of the sucrose octaacetate (SOA) avoidance-indifference dimorphism that exists among outbred CFW mice. In the first experiment, results from 687 subjects across three generations of segregation were consistent with predictions from a single-autosomal, two-allele model, with dominance for the avoidance (Taster) phenotype. In the second experiment, heterogeneous CFW Tasters and Nontasters were mated with SWR/J (Taster) and C57BL/6J (Nontaster) inbred mice. The SWR and CFW mice are both derived from Swiss mice, and the results were consistent with the possibility that the Taster animals share an allele which is identical by descent. The second and third experiments also investigated sensitivity to SOA across an extended range of concentrations. Nontaster CFWs avoided SOA at the near-saturation 10(-3) M concentration but did not avoid any weaker concentrations. Taster CFWs avoided all concentrations down to approximately 10(-6) M SOA.