Biology subjects

Rojas, G.

Publications and source records attributed to Rojas, G..

6 recordsLinked to original sources

bioRxiv2026

Cortical astrocytes control stress resilience

BackgroundChronic stress exposure is a risk factor for several psychiatric disorders, including post-traumatic stress disorder (PTSD) and major depression (MDD), with the prefrontal cortex (PFC) playing a key role in mediating this stress susceptibility. However, most individuals who are exposed to chronic stress are resilient and do not develop psychopathology. Recent evidence suggests that glial cells, especially astrocytes, play an important role in controlling stress-induced anxiety- and depression-like behavior, yet their role in contributing to stress resilience is not understood. MethodsUsing fiber photometry, chemogenetics, and RNA-sequencing in male mice, we establish a role for PFC astrocytes in stress resilience. ResultsWe demonstrate that stress-induced increases in astrocytic calcium activity are both necessary and sufficient for resilience. Bioinformatic analysis reveals robust transcriptional responses in PFC astrocytes that differ between susceptible vs. resilient mice and are unique when compared to astrocytic transcriptional changes in other limbic regions. Comparison with human RNA-sequencing data indicates that molecular changes observed in PFC astrocytes from susceptible mice converge with gene expression changes observed in MDD patients. ConclusionsTogether, these data support targeting astrocytes as a potential therapy for negative behavioral consequences following stress exposure and reveal potential molecular mechanisms within PFC astrocytes that could contribute to depressive-like behaviors.

neuroscience↗

bioRxiv2025

Astrocytic CREB regulates transcriptional, neuronal, and behavioral responses to cocaine

Drug addiction is characterized by neuronal adaptations that support a shift from goal-directed behaviors to habitual, compulsive drug-seeking with persistent effects on cognition and decision-making. Emerging evidence increasingly indicates that astrocytes are also involved in nervous system disorders, including addiction, but the cocaine-induced astrocyte-specific transcriptome has not yet been investigated. We utilized whole cell sorting of astrocytes, RNA-sequencing, and bioinformatic approaches to characterize the astrocyte transcriptome in the nucleus accumbens (NAc), a key brain region involved in reward-processing, following cocaine self-administration, prolonged abstinence, and "relapse" in male mice. We found that astrocytes exhibit robust and contextually-specific transcriptional signatures that converge strongly with human cocaine use disorder. Bioinformatic analysis revealed CREB as a highly ranked predicted upstream regulator of cocaine-induced transcriptional regulation in NAc astrocytes, and CUT&RUN-sequencing mapped increased CREB binding across the astrocyte genome in response to cocaine. Viral-mediated manipulation of CREB activity selectively in NAc astrocytes, in combination with several measures of addiction-related behaviors including conditioned place preference and self-administration, revealed that astrocytic CREB increases the rewarding and reinforcing properties of cocaine. This effect is sex-specific, with no change in astrocytic CREB activity or CPP found in females. Subsequent experiments identify potential molecular mechanisms of astrocytic CREBs influence through modulating astrocytic Ca2+ signaling in response to cocaine. Finally, we show that astrocytic CREB selectively modulates D1-type medium spiny neurons in NAc to control cocaine-related behaviors. Together, these data demonstrate that the astrocyte transcriptome responds robustly to cocaine and that CREB mediates cocaines effects on gene expression in astrocytes, with consequent effects on neuronal activity and rewarding responses to the drug.

neuroscience↗

bioRxiv2023

Voluntary alcohol intake alters the motivation to seek intravenous oxycodone and neuronal activation during the reinstatement of oxycodone and sucrose seeking

Opioid-alcohol polysubstance use is prevalent and worsens treatment outcomes. Here we assessed whether co-consumption of oxycodone and alcohol would influence intake of one another, demand for oxycodone, and the neurocircuitry underlying cue-primed reinstatement of oxycodone-seeking. Male and female rats underwent oxycodone intravenous self-administration (IVSA) with access to either alcohol (20% v/v) and water or only water immediately after the IVSA session. Next, economic demand for intravenous oxycodone was assessed while access to alcohol and/or water continued. Control rats self-administered sucrose followed by access to alcohol and/or water. Rats underwent extinction training and brains were processed for c-fos mRNA expression immediately following a cue-primed reinstatement test. While both sexes decreased oxycodone intake if they had access to alcohol, and decreased alcohol intake if they had access to oxycodone, female oxycodone+alcohol rats exhibited decreased demand elasticity for intravenous oxycodone and increased cue-primed reinstatement while male rats did not. Spontaneous withdrawal signs were correlated with oxycodone intake while alcohol intake was correlated with anxiety-like behavior. Alcohol consumption increased the number of basolateral and central amygdala neurons activated during sucrose and oxycodone reinstatement and the number of ventral and dorsal striatum neurons engaged by sucrose reinstatement. Nucleus accumbens shell dopamine 1 receptor containing neurons displayed activation patterns consistent with oxycodone reinstatement. Thus, alcohol alters the motivation to seek oxycodone in a sex-dependent manner and alters the neural circuitry engaged by cue-primed reinstatement of sucrose and oxycodone-seeking.

neuroscience↗

bioRxiv2021

In-solution buffer-free digestion for the analysis of SARS-CoV-2 RBD proteins allows a full sequence coverage and detection of post-translational modifications in a single ESI-MS spectrum

Subunit vaccines based on the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2, are among the most promising strategies to fight the COVID-19 pandemic. The detailed characterization of the protein primary structure by mass spectrometry (MS) is mandatory, as described in ICHQ6B guidelines. In this work, several recombinant RBD proteins produced in five expression systems were characterized using a non-conventional protocol known as in-solution buffer-free digestion (BFD). In a single ESI-MS spectrum, BFD allowed very high sequence coverage ([≥] 99 %) and the detection of highly hydrophilic regions, including very short and hydrophilic peptides (2-8 amino acids), the His6-tagged C-terminal peptide carrying several post-translational modifications at Cys538 such as cysteinylation, glutathionylation, cyanilation, among others. The analysis using the conventional digestion protocol allowed lower sequence coverage (80-90 %) and did not detect peptides carrying some of the above-mentioned post-translational modifications. The two C-terminal peptides of a dimer [RBD(319-541)-(His)6]2 linked by an intermolecular disulfide bond (Cys538-Cys538) with twelve histidine residues were only detected by BFD. This protocol allows the detection of the four disulfide bonds present in the native RBD and the low-abundance scrambling variants, free cysteine residues, O-glycoforms and incomplete processing of the N-terminal end, if present. Artifacts that might be generated by the in-solution BFD protocol were also characterized. BFD can be easily implemented and we foresee that it can be also helpful to the characterization of mutated RBD.

biochemistry↗

bioRxiv2021

SARS-CoV-2 RBD-Tetanus toxoid conjugate vaccine induces a strong neutralizing immunity in preclinical studies

Controlling the global COVID-19 pandemic depends, among other measures, on developing preventive vaccines at an unprecedented pace. Vaccines approved for use and those in development intend to use neutralizing antibodies to block viral sites binding to the hosts cellular receptors. Virus infection is mediated by the spike glycoprotein trimer on the virion surface via its receptor binding domain (RBD). Antibody response to this domain is an important outcome of the immunization and correlates well with viral neutralization. Here we show that macromolecular constructs with recombinant RBD conjugated to tetanus toxoid induce a potent immune response in laboratory animals. Some advantages of the immunization with the viral antigen coupled to tetanus toxoid have become evident such as predominant IgG immune response due to affinity maturation and long-term specific B-memory cells. This paper demonstrates that subunit conjugate vaccines can be an alternative for COVID-19, paving the way for other viral conjugate vaccines based on the use of small viral proteins involved in the infection process.

immunology↗

bioRxiv2019

Ventral Pallidum is Essential for Cocaine Reinstatement After Voluntary Abstinence

Addiction is a chronic relapsing disorder, and during recovery many people experience several relapse events as they attempt to voluntarily abstain from drug. New preclinical relapse models have emerged which capture this common human experience of relapse after voluntary abstinence, and mounting evidence indicates that reinstatement of drug seeking after voluntary abstinence recruits neural circuits distinct from reinstatement following experimenter-imposed abstinence, or abstinence due to extinction training. Ventral pallidum (VP), a key limbic node involved in drug seeking, has well-established roles in conventional reinstatement models tested following extinction training, but it is unclear whether this region also participates in more translationally-relevant models of relapse. Here we show that chemogenetic inhibition of VP neurons strongly attenuates cocaine-, context-, and cue-induced reinstatement tested after voluntary, punishment-induced abstinence. This effect was strongest in the most compulsive, punishment-resistant rats, and reinstatement was associated with neural activity in anatomically-defined VP subregions. VP inhibition also attenuated the propensity of rats to display hesitations, a risk assessment behavior seen during punished drug taking that is likely due to concurrent approach and avoidance motivations. These results indicate that VP, unlike other connected limbic brain regions, is essential for reinstatement of drug seeking after voluntary abstinence. Since VP inhibition effects were strongest in the most compulsively cocaine-seeking individuals, this could indicate that VP plays a particularly important role in the most pathological, addiction-like behavior, making it an attractive target for future therapeutic interventions.

neuroscience↗