👤 Daniela Santucci

Among ground-based paradigms used to reproduce altered gravity exposure, the hindlimb unloading (HU) model is widely employed to simulate microgravity conditions by removing gravitational loading from the hindlimbs. Despite its extensive use, behavioral adjustments during suspension remain poorly characterized, although they may provide valuable indicators of animal welfare and individual susceptibility. Here, we comprehensively characterized the behavioral profile of mice during and after HU using a dedicated ethogram, with the aim of identifying behavioral markers associated with individual coping strategies. Several exploratory and postural behaviors showed marked time-dependent modulation, with baseline exploratory activity predicting a more adaptive behavioral trajectory during suspension, possibly indicative of greater resilience. In parallel, brain levels of the neurotrophins NGF and BDNF were measured to explore their relationship with behavioral outcomes. Although no significant group differences were detected, suspended mice displayed a progressive reduction in both neurotrophins over time, which paralleled behavioral adaptation. Together, these findings indicate that specific exploratory behaviors represent reliable predictors of resilience to HU, while NGF and BDNF may reflect ongoing neuroplastic processes associated with prolonged suspension. Show less

We have recently demonstrated that human alpha-atrial natriuretic peptide (alpha-hANP), an amyloidogenic peptide responsible for isolated atrial amyloidosis, binds to a dimeric form of apo A-I belonging to small high-density lipoproteins (HDL). This binding phenomenon is considered a protective mechanism since it inhibits or strongly reduces the ANP aggregation process. The observation that plasma exhibits at least four times greater amyloid inhibitory activity than HDL prompted us to determine whether small HDL are the only ANP plasma-binding factors. After incubation of whole plasma with labelled ANP, the macromolecular complexes were subjected to two-dimensional gel electrophoresis followed by autoradiography. The results presented here provide novel evidence of additional binding proteins, in addition to apo A-I dimer, able to bind ANP in vitro and to prevent its aggregation. The mass spectrometry analysis of the radioactive spots identified them as albumin, alpha-1 antitrypsin, orosomucoid and apo A-IV-TTR complex. The putative impact of these findings in the amyloidogenic/antiamyloidogenic peptides network is discussed. Show less