Biology subjects

Bertelli, S.

Publications and source records attributed to Bertelli, S..

4 recordsLinked to original sources

bioRxiv2025

The polyamine naphthyl-acetyl spermine trihydrochloride (NASPM) lacks specificity for Ca2+-permeable AMPA receptors and suppresses seizure like activity in human brain tissue by inhibition of NMDA receptors.

For decades, naphthyl-acetyl spermine trihydrochloride (NASPM) has been used as a selective inhibitor of calcium-permeable AMPA receptors (CP-AMPAR). In rodents, NASPM is known to suppress seizures in vivo and seizure-like events (SLE) in vitro, suggesting possible involvement of CP-AMPAR in ictogenesis and epileptogenesis. To address whether these findings can be translated to human brain, we investigated the involvement of glutamatergic receptor subclasses in SLE in human cortex ex vivo, demonstrating that glutamatergic receptor antagonists can block (NASPM and APV) or reduce (UBP302, GYKI52466, GYKI53655) SLE. Using a multimethodological approach we were able to demonstrate that both NASPM and APV inhibit human SLE by inhibition of NMDA receptors. Our results further show that the inhibitory effect of NASPM on NMDA receptors is sufficient to explain its inhibition of seizure like activity, rather than its action on CP-AMPA receptors. Thus, our findings challenge previous knowledge on the use of NASPM as a specific CP-AMPAR inhibitor. Some phenomena previously attributed to CP-AMPAR, may need to be re-examined more closely. Overall, our study raises awareness about potential pitfalls in the use of existing pharmacological agents and sets a new paradigm for the use of NASPM in neuroscience research while questioning its therapeutic potential in a clinical context.

neuroscience↗

bioRxiv2024

Novel iGluSnFR3 variants with improved kinetics and dynamic range for tracking high frequency firing at glutamatergic synapses

The genetically-encoded fluorescent glutamate sensor, iGluSnFR3, characterised by a high dynamic range and rapid on-kinetics, is an attractive sensor for glutamate imaging in the central nervous system. However, kinetic variants with ultrafast or slow off-kinetics are needed to broaden the spectrum of applications from monitoring rapid synaptic glutamate transients to mesoscale imaging of brain activity. Here we report binding-site variant S72T (iGlu3Fast) optimised for reporting fast glutamate release at individual sites with a fluorescence dynamic range of 57 and a decay t1/2 of 2 ms in solution, [~]5-fold faster than iGluSnFR3. In contrast, variants D25A and D25R (termed iGlu3Slow1 and iGlu3Slow2, respectively) presented with slow off-kinetics (decay t1/2 43 ms and 30 ms, respectively, at 20{degrees}C), while retaining high dynamic ranges (48 and 65, respectively). These values were reduced when expressed in HEK293T cells, glutamate dissociation from iGlu3Fast slowed to a decay t1/2 of 6.9 ms, while decay t1/2-s of 115 and 234 ms were measured for iGlu3Slow1 and iGlu3Slow2, respectively. The slow decay rates in cells were in accordance with reduced Kd-s in the range of 200 M for iGlu3Fast and 6.4 and 8.4 M for iGlu3Slow1 and iGlu3Slow2, respectively. 2-photon imaging in organotypic hippocampal slices reported spontaneous activity with high sensitivity by both iGlu3Fast and iGlu3Slow2. Strikingly, different kinds of glutamate transient were detected by the fast- and slow-decay sensors indicating that the rapid kinetics and increased fluorescence dynamic range make iGlu3Fast an excellent candidate for imaging high-frequency glutamate release at synapses while iGlu3Slow2 has the potential for mesoscale imaging of brain activity to record global events with high sensitivity.

neuroscience↗

bioRxiv2023

An optogenetic method for the controlled release of single molecules

We developed a system for optogenetic release of single molecules in live cells. We confined soluble and transmembrane proteins to the Golgi apparatus via a photocleavable protein and released them by short pulses of light. Our method allows for the controlled delivery of functional proteins to cytosol and plasma membrane in amounts compatible with single molecule imaging, greatly simplifying access to single molecule microscopy of any protein in live cells. Furthermore, we could reconstitute cellular functions such as ion conductance by delivering BK and VRAC ion channels to the plasma membrane. Finally, we could induce NF-kB signaling in T-Lymphoblasts stimulated by IL-1 by controlled release of a signaling protein that had been knocked-out in the same cells. We observed light induced formation of functional inflammatory signaling complexes that could trigger IKK phosphorylation in single cells. We thus developed an optogenetic method for the reconstitution and investigation of cellular function at the single molecule level.

biophysics↗

bioRxiv2020

The anticipation and perception of affective touch in women with and recovered from Anorexia Nervosa

Disruptions in reward processing and anhedonia have long being considered as possible contributors to the aetiology and maintenance of Anorexia nervosa (AN). Recently, interoceptive deficits have also been observed in AN, including reduced tactile pleasure. However, the extent to which this tactile anhedonia is specifically liked to an impairment in a specialized, interoceptive C tactile system originating at the periphery, or a more top-down mechanism in the processing of pleasant tactile stimuli remains debated. Here, we investigated two related hypotheses. First, we examined whether the differences, between patients with AN and healthy controls in the perception of pleasantness of touch stimuli delivered in a CT-optimal manner versus a CT non-optimal manner would also be observed in patients recovered from AN. This is important as tactile anhedonia in acute patients may be the secondary result of prolonged malnutrition, rather than a deficit that contributed to the development of the disorder. Second, we examined whether these three groups would also differ in their top-down, anticipatory beliefs about the perceived pleasantness of different materials touching the skin, and to what degree such top-down beliefs and related impairments in alexithymia and interoceptive sensibility would explain any differences in perceived tactile plesantness. To this end, we measured the anticipated pleasantness of various materials touching the skin and the perceived pleasantness of light, dynamic stroking touches applied to the forearm of 27 women with AN, 24 women who have recovered and 30 healthy controls using C Tactile (CT) afferents-optimal (slow) and non-optimal (fast) velocities. Our results showed that both clinical groups anticipated tactile experiences and rated delivered tactile stimuli as less pleasant than healthy controls, but the latter difference was not related to the CT optimality of the stimulation. Instead, differences in how CT optimal touch were perceived were predicted by differences in top-down beliefs, alexithymia and interoceptive sensibility. Thus, this study concludes that tactile anhedonia in AN is not the secondary result of malnutrition but persists as a trait even after otherwise successful recovery of AN and also it not linked to a bottom-up interoceptive deficit in the CT system, but rather to a learned, defective top-down anticipation of pleasant tactile experiences.

neuroscience↗