Learned immobility explains the behavior of rats in the forced swimming test

The rat forced-swimming test (FST) is widely used for screening substances with a potential antidepressant effect. The rat immobility shown in the FST has been interpreted as "behavioral despair" and has been suggested as an animal model of human depression. In the following series of experiments it is shown that measuring rat mobility by an automatic recording device is more accurate than measuring immobility time by direct observation (Experiment 1 and 5). The automatic recording procedure was tested with imipramine and mianserin showing similar results to those reported in the literature using a direct observation procedure by the researcher (Experiment 2). In Experiment 3 it was demonstrated that: (a) rat mobility decreased with experience, (b) switching water depth on Day 2 of the test increased mobility and (c) anisomycin acts as a false positive. In Experiment 4 the possible state dependent effect of imipramine in the FST was studied. The effect of imipramine on rat behavior in the FST is not state dependent. The imipramine-saline group shows greater mobility than the saline-saline group and does not differentiate from the imipramine-imipramine group. Thus, it was suggested that imipramine could interfere with the acquisition and/or consolidation processes. In Experiment 5, it is shown that a single dose of 25 mg/kg of imipramine, administered before or immediately after training on Day 1, increases rat's mobility on Day 2, thus suggesting that imipramine alters the consolidation process. From these results it is suggested that the behavioral process involved in the FST is "learning to be immobile" instead of "behavioral despair" as previously suggested in the literature.     

Comparing the effectiveness of home visiting paraprofessionals and mental health professionals delivering a postpartum depression preventive intervention: a cluster-randomized non-inferiority clinical trial

To determine whether pregnant women receiving the Mothers and Babies group–based intervention exhibited greater depressive symptom reductions and fewer new cases of major depression than women receiving usual community-based services, and to examine whether groups run by paraprofessional home visitors and mental health professionals yielded similar depressive symptom reductions and prevention of major depression. Using a cluster-randomized design, 37 home visiting programs were randomized to usual home visiting, Mothers and Babies delivered via home visiting paraprofessionals, or Mothers and Babies delivered via mental health professionals. Baseline assessments were conducted prenatally with follow-up extending to 24 weeks postpartum. Eligibility criteria were ≥ 16 years old, ≤ 33 gestation upon referral, and Spanish/English speaking. Depressive symptoms at 24 weeks postpartum was the primary outcome. Eight hundred seventy-four women were enrolled. Neither intervention arm was superior to usual care in decreasing depressive symptoms across the sample (p = 0.401 home visiting paraprofessional vs. control; p = 0.430 mental health professional vs. control). Post hoc analyses suggest a positive intervention effect for women exhibiting mild depressive symptoms at baseline. We have evidence of non-inferiority, as the model-estimated mean difference in depressive symptoms between intervention arms (0.01 points, 95% CI: −0.79, 0.78) did not surpass our pre-specified margin of non-inferiority of two points. Although we did not find statistically significant differences between intervention and control arms, non-inferiority analyses found paraprofessional home visitors generated similar reductions in depressive symptoms as mental health professionals. Additionally, Mothers and Babies appears to reduce depressive symptoms among women with mild depressive symptoms when delivered by mental health professionals. This trial is registered on ClinicalTrials.gov (initial post: December 1, 2016; identifier: NCT02979444).

     

Evidence for linkage of nonsyndromic cleft lip with or without cleft palate to a region on chromosome 2

Results from a genome-wide screen of 10 multiplex families ascertained through probands with nonsyndromic cleft lip with or without cleft palate (CL/P) in Mexico, Argentina, and the United States yielded suggestive evidence of linkage to chromosomes 2, 6, 17 and 18. Fine mapping excluded all regions except chromosome 2. Subsequent analysis was performed on the original 10 families plus an additional 16 families using 31 markers on chromosome 2. This analysis showed intriguing evidence of linkage to 2q (Zlr=2.26, empirical P-value=0.028 in a chromosome-wide analysis). Transmission disequilibrium tests also revealed evidence of linkage and disequilibrium for two markers in this region (D2S168 and D2S1400 with P-values=0.022 and 0.006, respectively). A subset of these 26 families provided additional evidence for a susceptibility gene for CL/P on 2q, suggesting that further studies of genes in this region are warranted.     

Striatal oxidative damage parallels the expression of a neurological phenotype in mice transgenic for the mutation of Huntington's disease

We examined the degree of oxidative damage to the brain of mice transgenic for the mutation responsible for Huntington's disease. We found that there is a progressive increase in striatal lipid peroxidation (LP), that parallels the worsening of the neurological phenotype. We consider that these transgenic mice may provide an interesting system to test treatments aimed at protecting cells from damage induced by free radicals.