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Objectives To evaluate how often reproducible research practices, which allow others to recreate the findings of studies, given the original data, are used in systematic reviews (SRs) of biomedical research. Study Design and Setting We evaluated a random sample of SRs indexed in MEDLINE during February 2014, which focused on a therapeutic intervention and reported at least one meta-analysis. Data on reproducible research practices in each SR were extracted using a 26-item form by one author, with a 20% random sample extracted in duplicate. We explored whether the use of reproducible research practices was associated with an SR being a Cochrane review, as well as with the reported use of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Results We evaluated 110 SRs of therapeutic interventions, 78 (71%) of which were non-Cochrane SRs. Across the SRs, there were 2,139 meta-analytic effects (including subgroup meta-analytic effects and sensitivity analyses), 1,551 (73%) of which were reported in sufficient detail to recreate them. Systematic reviewers reported the data needed to recreate all meta-analytic effects in 72 (65%) SRs only. This percentage was higher in Cochrane than in non-Cochrane SRs (30/32 [94%] vs. 42/78 [54%]; risk ratio 1.74, 95% confidence interval 1.39–2.18). Systematic reviewers who reported imputing, algebraically manipulating, or obtaining some data from the study author/sponsor infrequently stated which specific data were handled in this way. Only 33 (30%) SRs mentioned access to data sets and statistical code used to perform analyses. Conclusion Reproducible research practices are underused in SRs of biomedical interventions. Adoption of such practices facilitates identification of errors and allows the SR data to be reanalyzed.

Orexinergic projections derived from the lateral hypothalamus (LH) to the ventral tegmental area (VTA) and the nucleus accumbens (NAc), play a key role in the acquisition of conditioned place preference (CPP) induced by LH stimulation. On the other hand, there are several studies which support the idea of the existence of a cross-talk between the orexinergic and cannabinoid systems. Nevertheless, the function and how both systems interact in the reward circuit remain unknown. In this study, the authors tried to clarify the role of orexin-2 receptor (OX2r) within the VTA and NAc in the development of reward-related behaviors after chemical stimulation of the LH and also find out the involvement of CB1 cannabinoid receptors in this phenomenon. Animals were implanted by two separate cannulae into the LH and VTA or NAc, unilaterally. The CPP paradigm was done; and conditioning scores were recorded. The results showed that administration of TCS OX2 29 as a selective OX2r antagonist (1, 3 and 10 nM/rat) into the VTA or NAc just 5 min before microinjection of carbachol (250 nM/0.5 μl saline), a cholinergic agonist, into the LH during the 3-day conditioning phase, could dose-dependently inhibit the development of LH stimulation-induced CPP. Furthermore, concurrent injection of ineffective doses of TCS OX2 29 and AM251, as a CB1 receptor antagonist, into the NAc could reduce conditioning scores. The findings of this study showed that the OX2 receptor has a critical role in modulating reward circuit in the VTA and NAc, when the LH was stimulated by carbachol. Moreover, we suggest the existence of an interaction between orexinergic and cannabinoid systems within the VTA and NAc in place preference induced by LH stimulation.