It has been shown for the first time by transmission electron microscopy that the hydrated fullerene C60 inhibited the fibrillization of amyloid-beta25-35 peptide. The fullerene affected the amyloid-beta25-35 assembly, manifesting its anti-amyloidogenic capacity. Our in vivo investigations demonstrated also that a single intracerebroventricular injection of the C60 hydrated fullerene at a dose of 7.2 nmol/ventricle significantly improved the performance of the cognitive task in control rats. The intracerebroventricular injection of the C60 hydrated fullerene (3.6 nmol/ventricle) prevented the impairment of performance of the cognitive task induced by amyloid-beta25-35 (22.5 nmol/ventricle). The results obtained may be useful in the development of therapy of Alzheimer's disease.

Chondroitin sulfate (CS) glycosaminoglycans inhibit regeneration in the adult central nervous system (CNS). We report here that HB-GAM (heparin-binding growth-associated molecule; also known as pleiotrophin), a CS-binding protein expressed at high levels in the developing CNS, reverses the role of the CS chains in neurite growth of CNS neurons in vitro from inhibition to activation. The CS-bound HB-GAM promotes neurite growth through binding to the cell surface proteoglycan glypican-2; furthermore, HB-GAM abrogates the CS ligand binding to the inhibitory receptor PTPσ (protein tyrosine phosphatase sigma). Our in vivo studies using two-photon imaging of CNS injuries support the in vitro studies and show that HB-GAM increases dendrite regeneration in the adult cerebral cortex and axonal regeneration in the adult spinal cord. Our findings may enable the development of novel therapies for CNS injuries.

It is widely acknowledged that the use of general anesthetics can undermine the relevance of electrophysiological or microscopical data obtained from a living animal's brain. Moreover, the lengthy recovery from anesthesia limits the frequency of repeated recording/imaging episodes in longitudinal studies. Hence, new methods that would allow stable recordings from non-anesthetized behaving mice are expected to advance the fields of cellular and cognitive neurosciences. Existing solutions range from mere physical restraint to more sophisticated approaches, such as linear and spherical treadmills used in combination with computer-generated virtual reality. Here, a novel method is described where a headfixed mouse can move around an air-lifted mobile homecage and explore its environment under stress-free conditions. This method allows researchers to perform behavioral tests (e.g., learning, habituation or novel object recognition) simultaneously with two-photon microscopic imaging and/or patch-clamp recordings, all combined in a single experiment. This video-article describes the use of the awake animal head fixation device (mobile homecage), demonstrates the procedures of animal habituation, and exemplifies a number of possible applications of the method.

Ketamine, a well-known anesthetic, has recently attracted renewed attention as a fast-acting antidepressant. A single dose of ketamine induces rapid synaptogenesis, which may underlie its antidepressant effect. To test whether repeated exposure to ketamine triggers sustained synaptogenesis, we administered a sub-anesthetic dose of ketamine (10 mg/kg i.p.) once-daily for 5 days, and repeatedly imaged dendritic spines of the YFP-expressing pyramidal neurons in somatosensory cortex of awake female mice using in vivo two-photon microscopy. We found that the spine formation rate became significantly higher at 72–132 h after the first ketamine injection (but not at 6–24 h), while the rate of elimination of pre-existing spines remained unchanged. In contrast to the net gain of spines observed in ketamine-treated mice, the vehicle-injected control mice exhibited a net loss typical for young-adult animals undergoing synapse pruning. Ketamine-induced spinogenesis was correlated with increased PSD-95 and phosphorylated actin, consistent with formation of new synapses. Moreover, structural synaptic plasticity caused by ketamine was paralleled by a significant improvement in the nest building behavioral assay. Taken together, our data show that subchronic low-dose ketamine induces a sustained shift towards spine formation.

Abstract:We studied the effects of aggregated amyloid β-peptide Аβ 25-35 on spatial memory and the spectral-correlational characteristics of EEG of both the dorsal hippocampus and the frontal cortex both in adult and aged rats at the early stage of Аβ 25-35 action. Spatial memory was characterized using a novel cognitive test. A decrease in low-frequency theta band oscillations in the dorsal hippocampus and the frontal cortex was observed. The mean coefficient of EEG cross-correlation between these structures was significantly reduced at the early stage of Aβ 25-35 action both in adult and aged rats. In addition, we found that one month after Aβ 25-35 injection spatial memory was impaired. These results suggest that the decrease in low-frequency theta band oscillations and the weakening of binding between the dorsal hippocampus and the frontal cortex under the action of Аβ 25-35 may be an underlying cause of the typical memory breakdown associated with the Alzheimer's disease.