Behavioral,neurochemical, and electrophysiological characterization of a genetic mouse model of depression

Depression is a multifactorial illness and genetic factors play a role in its etiology. The understanding of its physiopathology relies on the availability of experimental models potentially mimicking the disease. Here we describe a model built up by selective breeding of mice with strikingly different responses in the tail suspension test, a stress paradigm aimed at screening potential antidepressants. Indeed, "helpless" mice are essentially immobile in the tail suspension test, as well as the Porsolt forced-swim test, and they show reduced consumption of a palatable 2% sucrose solution. In addition, helpless mice exhibit sleep-wakefulness alterations resembling those classically observed in depressed patients, notably a lighter and more fragmented sleep, with an increased pressure of rapid eye movement sleep. Compared with "nonhelpless" mice, they display higher basal seric corticosterone levels and lower serotonin metabolism index in the hippocampus. Remarkably, serotonin(1A) autoreceptor stimulation induces larger hypothermia and inhibition of serotoninergic neuronal firing in the nucleus raphe dorsalis in helpless than in nonhelpless mice. Thus, helpless mice exhibit a decrease in serotoninergic tone, which evokes that associated with endogenous depression in humans. Finally, both the behavioral impairments and the serotoninergic dysfunction can be improved by chronic treatment with the antidepressant fluoxetine. The helpless line of mice may provide an opportunity to approach genes influencing susceptibility to depression and to investigate neurophysiological and neurochemical substrates underlying antidepressant effects.     

A randomized, double-blind clinical trial of two doses of meloxicam compared with naproxen in children with juvenile idiopathic arthritis: short- and long-term efficacy and safety results

OBJECTIVE: In an international, multicenter, double-blind, randomized clinical trial we evaluated the short-term (3 months) and long-term (12 months) efficacy and safety of 2 different doses of meloxicam oral suspension compared with the efficacy and safety of naproxen oral suspension in children with oligoarticular-course (oligo-course) or polyarticular-course (poly-course) juvenile idiopathic arthritis (JIA). METHODS: Children ages 2-16 years who had active oligo-course or poly-course JIA and who required therapy with a nonsteroidal antiinflammatory drug were eligible for this trial. Patients were randomly allocated to receive therapy with meloxicam oral suspension, 0.125 mg/kg body weight in a single daily dose; meloxicam oral suspension, 0.25 mg/kg body weight in a single daily dose; or naproxen, 10 mg/kg body weight in 2 daily doses. The trial drugs were administered in a double-blind, double-dummy design for up to 12 months. Response rates were determined according to the American College of Rheumatology pediatric 30% improvement criteria (ACR pediatric 30). Safety parameters were assessed by evaluating the frequency of adverse events in the 3 groups. RESULTS: Of 232 patients enrolled, 225 received treatment, 6 were not eligible for randomization, and 1 randomized patient was not treated. One hundred eighty-two patients (81%) completed the 12-month treatment period. Response rates according to the ACR pediatric 30 criteria improved from month 3 to month 12, as follows: from 63% to 77% in the meloxicam 0.125 mg/kg group, from 58% to 76% in the meloxicam 0.25 mg/kg group, and from 64% to 74% in the naproxen group. No statistically significant differences in response rates were observed between the groups. There were no differences in the frequency of adverse events or abnormal laboratory values between the 3 groups. CONCLUSION: The short- and long-term safety and efficacy of meloxicam oral suspension appear to be comparable with the safety and efficacy of naproxen oral suspension in the treatment of oligo-course and poly-course JIA. The once-daily administration of meloxicam oral suspension might represent an improvement in the treatment of JIA.     

A familial form of congenital hypopituitarism due to a PROP1 mutation in a large kindred: phenotypic and in vitro functional studies

We report the natural history of a hypopituitarism in a large Tunisian kindred including 29 subjects from the same consanguineous family. The index case was a 9-yr-old girl with severe growth retardation due to complete GH deficiency and partial corticotroph, lactotroph, and thyrotroph deficiencies. Magnetic resonance imaging showed a hyperplastic anterior pituitary. Thirteen of the 28 relatives examined (10 female subjects) had hypopituitarism. In the 14 patients, previously untreated (aged 6-53 yr), height was -5.7 +/- 1.7 sd score, and puberty was spontaneously initiated in only two females. Complete GH deficiency was found in all 12 patients investigated, of whom 11 had thyrotroph and eight of 10 had corticotroph deficiency. A homozygous R73C mutation of PROP1 was present in all 10 patients studied, and a heterozygous mutation was found in six unaffected parents or siblings. In vitro the mutant had 11.5% of the transactivation capacity of the wild type and was unable to bind to a high-affinity DNA sequence. This report showed the deleterious effect of the recessive R73C mutation that affects a hot spot of the PROP1 gene and was associated with severe dwarfism, a lack of spontaneous puberty, and a high incidence of early onset of corticotroph deficiency.     

Direct inhibition by nitric oxide of the transcriptional ferric uptake regulation protein via nitrosylation of the iron

Ferric uptake regulation protein (Fur) is a bacterial global regulator that uses iron as a cofactor to bind to specific DNA sequences. The function of Fur is not limited to iron homeostasis. A wide variety of genes involved in various mechanisms such as oxidative and acid stresses are under Fur control. Flavohemoglobin (Hmp) is an NO-detoxifying enzyme induced by NO and nitrosothiol compounds. Fur recently was found to regulate hmp in Salmonella typhimurium, and in Escherichia coli, the iron-chelating agent 2,2'-dipyridyl induces hmp expression. We now establish direct inhibition of E. coli Fur activity by NO. By using chromosomal Fur-regulated lacZ reporter fusion in E. coli, Fur activity is switched off by NO at micromolar concentration. In vitro Fur DNA-binding activity, as measured by protection of restriction site in aerobactin promoter, is directly sensitive to NO. NO reacts with Fe(II) in purified FeFur protein to form a S = 12 low-spin FeFur-NO complex with a g = 2.03 EPR signal. Appearance of the same EPR signal in NO-treated cells links nitrosylation of the iron with Fur inhibition. The nitrosylated Fur protein is still a dimer and is stable in anaerobiosis but slowly decays in air. This inhibition probably arises from a conformational switch, leading to an inactive dimeric protein. These data establish a link between control of iron metabolism and the response to NO effects.     

The p20 and Ded1 proteins have antagonistic roles in eIF4E-dependent translation in Saccharomyces cerevisiae

The translation initiation factor eIF4E mediates the binding of the small ribosomal subunit to the cap structure at the 5′ end of the mRNA. In Saccharomyces cerevisiae, the cap-binding protein eIF4E is mainly associated with eIF4G, forming the cap-binding complex eIF4F. Other proteins are detected upon purification of the complex on cap-affinity columns. Among them is p20, a protein of unknown function encoded by the CAF20 gene. Here, we show a negative regulatory role for the p20 protein in translation initiation. Deletion of CAF20 partially suppresses mutations in translation initiation factors. Overexpression of the p20 protein results in a synthetic enhancement of translation mutation phenotypes. Similar effects are observed for mutations in the DED1 gene, which we have isolated as a multicopy suppressor of a temperature-sensitive eIF4E mutation. The DED1 gene encodes a putative RNA helicase of the DEAD-box family. The analyses of its suppressor activity, of polysome profiles of ded1 mutant strains, and of synthetic lethal interactions with different translation mutants indicate that the Ded1 protein has a role in translation initiation in S. cerevisiae.