Biology subjects

Valenzuela, C. F.

Publications and source records attributed to Valenzuela, C. F..

8 recordsLinked to original sources

bioRxiv2026

Epileptiform Discharges Drive High-frequency Oscillations Within the Retrosplenial Cortex of Mice with Third Trimester Alcohol Exposure

Fetal Alcohol Spectrum Disorders (FASDs) are associated with alterations in learning and memory that persist throughout the lifespan. Thus, determining the neural mechanisms driving these alterations has the potential to identify novel therapeutic targets for improving memory in those with FASD. Given the newly realized role of the Retrosplenial cortex (RSC) for learning and memory, as well as the profound neural apoptosis that exposure to alcohol during development causes to this brain region, we recorded electrophysiological activity from mice exposed to alcohol during the third trimester-equivalent developmental time period. We observed a large number of Epileptiform Discharges (EDs) in alcohol-exposed subjects compared to controls, which were found to drive with High-frequency Oscillations (HFOs). Furthermore, many features of HFOs (amplitude/duration/etc.) were found to be directly proportional to the temporal distance from ED onset. These findings identify EDs for the first time as a critical feature in a preclinical model of FASD, and suggest their relationship to RSC HFOs may be a key mechanism driving memory alterations.

neuroscience↗

bioRxiv2026

Third Trimester-Equivalent Alcohol Exposure Reduces Neurons in Males and Increases Vglut2⁺ Neurons with Reduced Intrinsic Bursting in Females in The Murine Dorsal Subiculum

Individuals with Fetal Alcohol Spectrum Disorders (FASDs) show reduced subicular volume, and preclinical studies compliment this by demonstrating that third-trimester-equivalent ethanol exposure induced apoptosis in corticolimbic regions, including the subiculum. The subiculum mediates hippocampal-cortical communication critical for long-term memory consolidation. Within the distal dorsal subiculum, a population of bursting neurons uniquely express VGLUT2 and they play a key role in memory processing. We hypothesized that third-trimester-equivalent ethanol exposure would reduce neuronal and VGLUT2+ cell density in the dorsal subiculum and reduce the excitability of bursting neurons, providing a mechanism for long-term memory impairments observed in FASD. To test this, postnatal day (P)7 mice received a subcutaneous injection of ethanol and long-term effects were assessed in adolescence (P35-62). Using transgenic mice with fluorescently labeled VGLUT2+ neurons, and immunohistochemistry we observed a significant reduction in neuronal density in males and an increase in VGLUT2+ cell density in females. Using whole-cell patch clamp electrophysiology, we observed a reduction in action potentials per burst in both sexes. Additionally, females showed reduced overall excitability, and a subset of neurons exhibited a shift to regular spiking. These findings suggest that development ethanol exposure disrupts subicular output by impairing burst firing, potentially weaking hippocampal-cortical communication and contributing to the cognitive deficits associated with FASD. HighlightsO_LIThird-trimester ethanol targets VGLUT2+ neurons in the dorsal subiculum C_LIO_LIEthanol reduced neuronal density in male dorsal subiculum C_LIO_LIEthanol increases VGLUT2+ cell density in females C_LIO_LIEthanol reduces action potential per burst in both sexes C_LIO_LIFemales show reduced excitability and loss of bursting in some cells C_LI

neuroscience↗

bioRxiv2026

Third Trimester-Equivalent Alcohol Exposure Induces Sex-Dependent Alterations in Locomotor Activity, Anxiety-Risky Behaviors, and Enhances Mechanical Allodynia in Adulthood

Prenatal alcohol exposure (PAE) causes fetal alcohol spectrum disorders (FASDs), which are neurodevelopmental conditions characterized by behavioral dysregulation, learning deficits, and cognitive inflexibilities. Alcohol exposure is harmful at all stages of human gestation, including the third trimester. This developmental window--characterized by rapid brain growth, myelination, and neural circuit formation--may be particularly vulnerable, yet the long-lasting behavioral and sensory consequences of exposure during this period remain poorly understood. In this study, neonatal mouse pups were exposed to ethanol (EtOH) or air vapor from postnatal day (P) 4 to P8, which is equivalent to a third-trimester alcohol exposure (TTAE) in humans. Blood ethanol concentrations measured at P8 reached approximately 250 mg/dL, consistent with binge-level exposure. Air- and EtOH-exposed mice were then assessed as adults at 5-6 months of age for locomotor activity, anxiety-related risky behaviors, recognition memory, and increased susceptibility to peripheral neuropathy, as indicated by sensitization to light touch following minor chronic constriction injury (mCCI) of the sciatic nerve. We found that TTAE was sufficient to produce long-lasting behavioral outcomes in a sex-dependent manner. Notably, EtOH-exposed males exhibited increased spontaneous locomotor activity and risky behavior, whereas EtOH-exposed females showed minimal or decreased changes compared to their respective controls. However, both EtOH-exposed male and female mice exhibited marked increases in light-touch sensitization, referred to as mechanical allodynia, following mCCI, a response absent in air-exposed controls. Together, these findings reveal that TTAE is highly detrimental to behavioral regulation and creates a vulnerability to developing neuropathic pain in adulthood.

neuroscience↗

bioRxiv2025

ALCOHOL AUGMENTS SPONTANEOUS GABAERGIC TRANSMISSION AND ACTION POTENTIAL FIRING IN IMMATURE MURINE CEREBELLAR GOLGI CELLS, LEADING TO ENHANCED INHIBITORY INPUT ONTO CEREBELLAR GRANULE CELLS

Golgi cells (GoCs) are cerebellar inhibitory interneurons that provide both phasic and tonic GABAergic input to cerebellar granule cells. They receive inhibitory control from Lugaro cells, other GoCs, and cerebellar nuclear inhibitory neurons via GABAergic and glycinergic inputs. Although fetal alcohol exposure is known to impair cerebellar function, its impact on developing GoC physiology remains unclear. We investigated the acute effects of ethanol on GABAA receptor-mediated transmission in GoCs during the mouse equivalent of the human third trimester, a critical window for inhibitory circuit formation. To identify GoCs, we used VGAT-Venus transgenic mice, in which the vesicular GABA transporter promoter drives expression of the Venus fluorescent protein. Whole-cell patch-clamp and loose-patch recordings from postnatal day (P) 6-10 mice revealed that ethanol exposure dose-dependently increased the frequency of action potential-dependent GABAA receptor-mediated spontaneous postsynaptic currents (sPSCs) in GoCs. While ethanol produced variable effects on GoC firing rates, it more consistently enhanced GABAA-sPSC frequency in granule cells. We also examined expression of the K+-Cl- cotransporter 2 (KCC2), a chloride exporter whose developmental upregulation drives the shift in GABAA receptor signaling from excitatory to inhibitory. Immunohistochemical analysis at P6 showed that GoCs express low levels of KCC2, suggesting that GABAA receptor- mediated currents may remain depolarizing in a subset of GoCs. This property could contribute to ethanol-induced disruption of cerebellar circuit maturation. Together, these findings provide new insight into the cellular mechanisms by which ethanol perturbs inhibitory circuit development in the cerebellum.

neuroscience↗

bioRxiv2025

Prenatal alcohol exposure promotes nerve injury-induced pathological pain following morphine treatment via NLRP3-mediated peripheral and central proinflammatory immune actions.

Adverse in-utero conditions may exert a lifelong impact on neuroimmune function. Our prior work showed that prenatal alcohol exposure (PAE) increases pathological pain sensitivity (allodynia) following peripheral sciatic nerve injury. While the immune mechanism(s) of PAE-induced immune dysfunction are poorly understood, prior studies implicated the involvement of Toll-like receptor 4 (TLR4) and the nucleotide-binding domain, leucine-rich repeat-containing family, pyrin domain-containing 3 (NLRP3) inflammasomes. Interestingly, emerging data suggest a surprising overlap of spinal glial proinflammatory activation via the TLR4-NLRP3-interleukin (IL)-1{beta} axis due to opioid treatment in nerve-injured non-PAE rodents. Considering this preclinical evidence, we explored whether PAE poses a risk factor in creating proinflammatory immune bias consequent to opioid (morphine) exposure. We hypothesized that under nerve injury conditions, PAE may interact with morphine, promoting peripheral and CNS proinflammatory factors in a NLRP3-dependent manner. Using a minor nerve injury model in adult mice, we demonstrate that PAE prolongs the chronicity of ongoing allodynia in both sexes, with a more pronounced effect observed in male mice. Our study shows that PAE amplifies proinflammatory responses at the injury site and the spinal cord, driving morphine-prolonged allodynia through NLRP3 inflammasome activation. Furthermore, high mobility group box 1 (HMGB1), a well-established pain-promoting TLR4 agonist, is elevated in allodynic PAE mice. NLRP3 inhibitor, MCC950, effectively reverses morphine-induced allodynia and reduces Caspase-1 activity, IL-1{beta}, and related proinflammatory factors. Although few sex-specific effects were observed, our data convincingly support that PAE and morphine interactions ultimately converge on NLRP3-driven mechanisms in both sexes. Together, this study suggests that PAE modulates later-life neuroimmune function and provides critical insights into immune regulators underlying PAE-induced biological vulnerability to pathological pain processing and adverse effects of opioids.

neuroscience↗

bioRxiv2024

Connectivity of the neuronal network for contextual fear memory is disrupted in a mouse model of third-trimester binge-like ethanol exposure

BackgroundIn rodents, third-trimester equivalent alcohol exposure (TTAE) produces significant deficits in hippocampal-dependent memory processes such as contextual fear conditioning (CFC). The present study sought to characterize changes in both behavior and Fos+ neurons following CFC in ethanol (EtOH)-treated versus saline-treated mice using TRAP2:Ai14 mice that permanently label Fos+ neurons following a tamoxifen injection. We hypothesized that TTAE would produce long-lasting disruptions to the networks engaged following CFC with a particular emphasis on the limbic memory system. MethodsOn postnatal day 7, mice received either two injections of saline or 2.5 g/kg EtOH spaced 2 hours apart. The mice were left undisturbed until they reached adulthood, at which point they underwent CFC. After context exposure on day 2, mice received a tamoxifen injection. Brain tissue was harvested. Slides were automatically imaged using a Zeiss AxioScanner. Manual counts on a priori regions of interest were conducted. Automated counts were performed on the whole brain using the QUINT 2D stitching pipeline. Last, novel network analyses were applied to identify future regions of interest. ResultsTTAE reduced context recall on day 2 of CFC. Fos+ neural density increased in the CA1 and CA3. Fos+ counts were reduced in the anteroventral (AV) and anterodorsal thalamus. The limbic memory system showed significant hyperconnectivity in male TTAE mice and the AV shifted affinity towards hippocampal subregions. Last, novel regions such as a subparafascicular area and basomedial amygdalar nucleus were implicated as important mediators. DiscussionThese results suggest that CFC is mediated by the limbic memory system and is disrupted following TTAE. Given the increase in CA1 and CA3 activity, a potential hypothesis is that TTAE causes disruptions to memory encoding following day 1 conditioning. Future studies will aim to determine whether this disruption specifically affects the encoding or retrieval of fear memories.

neuroscience↗

bioRxiv2024

Maternal Alcohol Drinking Patterns Predict Offspring Neurobehavioral Outcomes

SIGNIFICANCEThe timing, rate, and quantity of gestational alcohol consumption, collectively referred to here as Maternal Drinking Patterns (MDPs), are of known importance to fetal developmental outcomes. Though studies in rodents exist that have investigated the impact of gestational alcohol drinking characteristics, few have sought to determine the impact of MDPs on offspring behavioral outcomes. METHODSWe first used specialized equipment to record the precise amount and timing of binge alcohol consumption in pregnant mouse dams, and then characterized MDPs using Principle Component Analysis (PCA). We focused these analyses on the first fifteen minutes of every gestational drinking session when dams consumed the majority of each sessions alcohol (a phenomenon known as front-loading), as well as the entire 2 hour session across all days of gestation. We next tested offspring in open field and rotarod assays and evaluated these behavioral results in the context of MDPs. RESULTSMale alcohol exposed mice exhibited longer latencies to fall on the rotarod compared to their controls, which we attribute to a delayed decrease in body weight-gain not observed in females. This effect was found to be associated with MDPs within the first fifteen minutes of drinking, but not other MDPs. Female alcohol exposed mice had significantly reduced total locomotor activity in the open field compared to controls, and this effect was also associated with MDPs but only of the entire drinking session. Surprisingly, total gestational alcohol consumption alone was not associated with any particular behavioral outcome. Furthermore, we replicated robust behavioral data demonstrating development of allodynia in alcohol exposed mice where it did not develop in controls. CONCLUSIONSTo our knowledge, this report represents the highest resolution assessment of alcohol drinking throughout gestation, and one of few to have identified relationships between specific alcohol MDPs and neurobehavioral outcomes in offspring. Specifically, based on characteristics of the PCA groups, we found evidence that the rate of alcohol front-loading leads to developmental delays in males, whereas an interaction of front-loading rate and duration, overall persistence, and total amount consumed lead to a female-only decrease in locomotor activity. Beyond these results, we provide a method for precise and accessible tracking of such data.

neuroscience↗

bioRxiv2020

Enhancement of parvalbumin interneuron-mediated neurotransmission in the retrosplenial cortex of adolescent mice following third trimester-equivalent ethanol exposure

Prenatal ethanol exposure causes a variety of cognitive deficits that have a persistent impact on quality of life, some of which may be explained by ethanol-induced alterations in interneuron function. Studies from several laboratories, including our own, have demonstrated that a single binge-like ethanol exposure during the equivalent to the third trimester of human pregnancy leads to acute apoptosis and long-term loss of interneurons in the rodent retrosplenial cortex (RSC). The RSC is interconnected with the hippocampus, thalamus, and other neocortical regions and plays distinct roles in visuospatial processing and storage, as well as retrieval of hippocampal-dependent episodic memories. Here we used slice electrophysiology to characterize the acute effects of ethanol on GABAergic neurotransmission in the RSC of neonatal mice, as well as the long-term effects of neonatal ethanol exposure on parvalbumin-interneuron mediated neurotransmission in adolescent mice. Mice were exposed to ethanol using vapor inhalation chambers. In postnatal day (P) 7 mouse pups, ethanol unexpectedly failed to potentiate GABAA receptor-mediated synaptic transmission. Binge-like ethanol exposure of P7 mice expressing channel rhodopsin in parvalbumin-positive interneurons enhanced the peak amplitudes, asynchronous activity and total charge, while decreasing the rise-times of optically-evoked GABAA receptor-mediated inhibitory postsynaptic currents in adolescent animals. These effects could partially explain the learning and memory deficits that have been documented in adolescent and young adult mice exposed to ethanol during the third trimester-equivalent developmental period.

neuroscience↗