Acute alcohol intoxication (AAI) poses serious health risks. Currently, no approved therapy effectively treats both CNS depression and tissue damage in AAI. Standard care, including supportive measures and off-label naloxone, manages respiratory depression but fails to prevent oxidative organ injury. We identified morin (MOR) as a promising candidate for addressing these challenges. Given that MOR is limited by poor water solubility and low oral bioavailability, we developed water-soluble nano-micelle formulations (MOR-Ms) using Kolliphor HS15 (HS15) as a surfactant for intravenous administration. The resulting MOR-Ms exhibited a uniform size of 13.84 ± 0.23 nm and a zeta potential of −9.99 ± 0.21 mV. In vivo, MOR-Ms accelerated alcohol metabolism by enhancing hepatic enzyme activity. In an AAI mouse model induced by intraperitoneal injection of 50% alcohol (10 ml/kg), MOR-Ms (3 mg/kg) significantly shortened the duration of loss of righting reflex (LORR) by 58.01%, which was comparable to the 67.83% reduction achieved by naloxone (1 mg/kg). Furthermore, MOR-Ms markedly lessened tissue damage by decreasing malondialdehyde (MDA) levels (by 32.01% in liver and 53.75% in brain compared to the model group) and boosting antioxidant enzyme activity. These results highlight the potential of MOR-Ms as a promising therapeutic approach for AAI.

Brain-penetrant microtubule-stabilizer epothilone B delays isoflurane-induced unconsciousness in mice.

Study objectivesTo investigate the interaction and potential mechanisms of the combined administration of dexmedetomidine (DMED) and eszopiclone (ESZ) on sleep in mice.MethodsThe effects of DMED, ESZ and the combination of the two drugs on the sleep status of mice were investigated by using the loss of righting reflex (LORR) as an indicator, the sleep-related parameters were recorded, and the interactions of the combination of DMED and ESZ on sleep were determined by isobolographic analysis. The effects of DMED and ESZ on sleep structure, the regulation of c-Fos protein expression in the ventrolateral preoptic area (VLPO) and the tuberomammillary nucleus (TMN) and the regulation of neurotransmitter levels were further investigated by combining electroencephalogram/electromyogram (EEG/EMG) sleep phase analysis, c-Fos immunofluorescence, and neurotransmitter content measurements in the brain.ResultsIsobolographic analysis demonstrated that the combination of DMED and ESZ had a synergistic effect on sleep in mice. The duration of non-rapid eye movement (NREM) sleep was significantly prolonged; the number of c-Fos positive neurons increased in the VLPO and decreased in the TMN; the levels of excitatory neurotransmitters were reduced, while the levels of inhibitory neurotransmitters were elevated.ConclusionThis study reveals that the combination of DMED and ESZ exerts a synergistic effect on sleep in mice. The underlying mechanism may involve the prolongation of NREM sleep, modulation of neuronal activity in the brain regions of VLPO and TMN, as well as alteration in the levels of brain neurotransmitters.

Inhaled anesthetics were first introduced into clinical use in the 1840s. Molecular and transgenic animal studies indicate that inhaled anesthetics act through several ion channels, including γ-aminobutyric acid type A receptors (GABAARs) and two-pore domain K+ (K2P) channels, but other targets may mediate anesthetic effects. Mutations in the type 1 ryanodine receptor (RyR1), which is a calcium release channel on the endoplasmic reticulum membrane, are relevant to malignant hyperthermia, a condition that can be induced by inhaled anesthetics. However, it was previously uncertain whether inhaled anesthetics directly interact with RyR1. In our study, we demonstrated that isoflurane and other inhaled anesthetics activate wild-type RyR1. By employing systematic mutagenesis, we discovered that altering just one amino acid residue negates the response to isoflurane, thus helping us to pinpoint the potential binding site. Knock-in mice engineered to express a mutant form of RyR1 that is insensitive to isoflurane exhibited resistance to the loss of righting reflex (LORR) when exposed to isoflurane anesthesia. This observation suggests a connection between RyR1 activation and the anesthetic effects in vivo. Moreover, it was shown that RyR1 is involved in the neuronal response to isoflurane. Additionally, administering new RyR1 agonists, which share the same binding site as isoflurane, resulted in a sedation-like state in mice. We propose that isoflurane directly activates RyR1, and this activation is pertinent to its anesthetic/sedative effects.

Although substantial progress has been made in the last three decades towards our understanding of how general anesthetics (GAs) act at the molecular level, much less is known about how GAs cause loss of consciousness at the level of neuronal networks. The role of thalamus as an important brain region in anesthetic-induced hypnosis is relatively well established, but the specific roles of voltage-gated ion channels in different functional regions of the thalamus in anesthetic mechanisms are not well studied. To address this gap in knowledge, we selectively silenced the Cacna1g gene that encodes the low-threshold-activated CaV3.1T-type voltage-gated calcium channel subunit by injecting short-hairpin RNA (shRNA) into midline and intralaminar - nonspecific thalamus (MIT) and sensory - specific ventrobasal (VB) thalamic nuclei in wild-type (WT) mice. Control animals were injected with scrambled shRNA. To validate our silencing approach, we performed patch-clamp experiments in acute thalamic slices ex vivo. In injected animals we determined anesthetic endpoints such as hypnosis measured with loss of righting reflex (LORR) and immobilization measured with loss of withdrawal reflex (LOWR) in vivo after administration of a traditional volatile GA isoflurane. Effective CaV3.1 channel knock-down was documented by greatly diminished amplitudes of T-currents and absence of rebound burst firing in our patch-clamp recordings from thalamic slices. We found that knocking down CaV3.1 channels in MIT significantly decreased inhaled isoflurane concentration that is required to induce LORR, but it did not affect speed of anesthetic induction and the immobilizing effect of isoflurane. In contrast, knocking down the CaV3.1 channel in the VB thalamus did not affect any of the measured anesthetic endpoints. Hence, we concluded that CaV3.1 channels in nonspecific MIT thalamus have a preferential role in anesthetic hypnosis when compared to the sensory VB thalamus.

Zuranolone (SAGE-217), the first FDA-approved oral neurosteroid (NAS), a positive allosteric modulator (PAM) of γ-aminobutyric acid type A (GABAA) receptor for postpartum depression approved in 2023, has limitations such as short half-life, low bioavailability, and central inhibitory side effects. To address these, we designed novel C-21 modified derivatives of Zuranolone, identifying the triazolone scaffold as key for enhancing GABAA activity. Here, we synthesized Zuranolone analogs with diverse triazolone substituents, finding that pyridine-derived modifications improved the activity correlated with LogP. The optimal derivative, S9 (2-(trifluoroethoxy)pyridine-triazolone, LogP 4.61), showed 2.5-fold greater potency (EC50) and efficacy (Emax) than Zuranolone (LogP 4.78) at synaptic/extrasynaptic GABAA receptors, attributed to stronger binding via molecular docking. In rats, S9 exhibited 5-fold longer plasma T1/2, 6-fold higher AUC, 3-fold greater brain exposure, and 30% improved bioavailability. It also outperformed Zuranolone in pentylenetetrazole (PTZ)-induced seizure suppression and threshold dose for loss of righting reflex (LORR) in rats. The C21-pyridine-triazolone pharmacophore in S9 enhances receptor activity potency without increasing lipophilicity, optimizing pharmacokinetics and safety, which makes it a promising therapeutic candidate for depression and epilepsy.

BackgroundEtomidate-induced myoclonus has become a pressing clinical problem with an incidence of 50–80%. The underlying mechanism involves neocortical glutamate accumulation and N-methyl-d-aspartate (NMDA) receptor activity. However, the therapeutic target remains uncertain.MethodsAdult male Sprague-Dawley (SD) rats were injected with etomidate (1.5 mg/kg), propofol (11.8 mg/kg), and lidocaine (4.0 mg/kg) plus etomidate (1.5 mg/kg), etomidate (3.8 mg/kg), etomidate (6.0 mg/kg) through the tail vein and behavioral scores of the rats were recorded within 5 min after anesthesia to establish the model of etomidate-induced myoclonus and to observe the dose dependence. The in vitro Western blot analysis of NKCC1 and KCC2 proteins and the regulatory effect of N-methyl-d-aspartate (NMDA) receptor were performed to find the potential target of etomidate-induced myoclonus or excitability. Additionally, to verify whether calpain-2 is involved in the process of regulatory effect of NMDAR on the cleavage of KCC2 protein during etomidate-induced myoclonus, muscular tension and KCC2 protein were analyzed in rats microinjected with calpain-2 inhibitor (MDL-28170) or MDL-28170 + NMDA in the neocortical motor cortex during etomidate anesthesia. Finally, MDL-28170 or vitamin E was injected intravenously before etomidate, the muscular tension, KCC2 protein and duration of loss of righting reflex (LORR) of rats were evaluated to verify the neuroprotective effect of vitamin E.ResultsEtomidate significantly increased the mean behavioral score at different time points compared with the propofol and lidocaine + etomidate groups within 5 min after anesthesia; the mean behavioral score decreased at different time points with increasing dose of etomidate. 0.5 µM ( 0.73 ± 0.18 vs. 1.04 ± 0.17, n = 6, p = 0.0096) and 1 µM (0.73 ± 0.24 vs. 1.03 ± 0.14, n = 6, p = 0.0077) etomidate induced the decrement of neocortical KCC2 protein compared to the control group. NMDA activated but 2-amino-5-phosphonopentanoic acid (AP5) inhibited 0.5 and 1 µM etomidate-induced decrement of neocortical KCC2 protein. MDL-28170 microinjected into the neocortex during etomidate anesthesia not only inhibited the decrement of KCC2 protein but also blocked the muscular tension induced by etomidate alone or etomidate plus NMDA. Intravenous injection of vitamin E prevented etomidate-induced muscular tension and decrement of the KCC2 protein.ConclusionCalpain-2 was involved in the process of etomidate-induced myoclonus and NMDAR activity by promoting the decrement of KCC2 protein and exerting the excitability. Vitamin E, as a natural antioxidant, can effectively prevent etomidate-induced myoclonus and does not affect recovery after etomidate anesthesia in rats.

BackgroundMicrotubules (MTs) have been postulated as one of the molecular targets underlying loss of consciousness induced by inhalational anesthetics. Microtubule-targeting chemotherapy drugs and opioids affect MT stability and function. However, the impact of prolonged administration of these drugs on anesthetic potency and anesthesia induction and emergence times remain unelucidated.MethodsEpothilone D, paclitaxel, vinblastine or opioid morphine were administered alone for a prolonged period (> 2 weeks) to male CD1 mice and their sensitivity to incremental concentrations of isoflurane were examined using loss of righting reflex (LORR) response as a measure of sensivity. The induction and emergence time after administration and termination of fixed concentration of isoflurance (1.2%) were also assessed.ResultsCompared with saline treatment, epothilone D and vinblastine induced a leftward (more sensitive) shift of LORR response curves (95% confidence intervals for EC50: epothilone D, 0.75[0.73, 0.77] vs. saline, 0.97[0.96, 0.98]; vinblastine, 0.74[0.73, 0.75] vs. saline, 0.98[0.97, 0.99]). In contrast, morphine caused a rightward (more resistant) LORR response curve (morphine, 1.16[1.15, 1.17] vs. saline, 0.97[0.96, 0.98]), while paclitaxel produced a marginal but significant rightward shift of LORR (paclitaxel, 1.05[1.03, 1.06] vs. saline, 0.98[0.97, 0.99]). At concentration of 1.2% isoflurane, morphine treatment prolonged (275 ± 50) and vinblastine treatment reduced (96.5 ± 26) the anesthetic induction latency (in second) relative to saline treatment (211 ± 39). The latency of emergence from anesthesia was shorter in morphine (58 ± 20) and vinblastine-treated (98 ± 43) mice compared to saline (176 ± 50) treatment. The induction or emergence latencies of epothilone D or paclitaxel treatment did not differ from saline treatment between groups.ConclusionsMicrotubule-modulating drugs can affect not only sensitivity but also induction and emergence times to inhalational anesthetic isoflurane in mice. This study highlights a possible role of MTDs in modulating anesthetic effects in disparate directions, which has implications for anesthetic concentrations that should be used for induction, maintenance and emergence of anesthesia. These findings in rodents may have relevance to the perioperative care of cancer patients who receive MT-targeting chemotherapy drugs or even opioids for pain for prolonged periods.

Spinosin, a key flavonoids component found in Semen Zizhiphi spinosae, is known to enhance pentobarbital-induced sleep, which is primarily assessed with the loss-of-righting reflex (LORR). This research focused on investigating the impact of spinosin on sleep regulation in typical murine models. We used electroencephalogram (EEG) and electromyogram (EMG) recordings to evaluate the effects of spinosin (10, 20, 40 mg/kg, i.p.) on sleep-wake state. Immunohistochemical techniques were employed to investigate the c-Fos expression in various sleep-wake brain regions following the injection of spinosin. In the initial three-hour period following administration, spinosin administered at a dose of 40 mg/kg exhibited a notable augmentation in the duration of non-rapid eye movement (NREM) sleep, with a 2.04-fold increase (P < 0.0001), accompanied by a reduction in wakefulness by approximately 42.84% (P < 0.0001) compared to the vehicle group. Immunohistochemical analysis revealed an enhancement in c-Fos expression within the accumbens nucleus (Acb) when treated with spinosin at 40 mg/kg. In contrast, a notable reduction in c-Fos expression was detected across various brain regions, including the paraventricular thalamic nucleus (PV), lateral hypothalamic area (LHA), ventrolateral periaqueductal gray (VLPAG), dorsal raphe nucleus (DR), and lateral parabrachial nucleus (LPB) (P < 0.05). In addition, the treatment resulted in an increase in c-Fos expression within gamma-aminobutyric acid (GABAergic) neurons in the Acb, while simultaneously decreasing c-Fos expression in orexin neurons within the LHA. The results indicate that spinosin (40 mg/kg, i.p.) enhances NREM sleep in mice. Moreover, heightened activity of GABAergic neurons in the Acb and reduced activity of orexin neurons in the LHA may be the pathway through which spinosin promotes sleep.

PurposeTo investigate the role of brain noradrenergic and orexinergic activity in ketamine-induced sedation.MethodsWe used orexin neuron-deficient transgenic rats (orexin/ataxin-3) and wild-type controls. Noradrenaline and orexin levels were measured in the pons, hypothalamus, and cerebral cortex. Ketamine-induced loss-of-righting reflex (LORR) was assessed under modulation of noradrenergic or orexinergic activity.ResultsWild-type rats had higher noradrenaline and orexin levels than transgenic rats across all regions except hypothalamic noradrenaline. Noradrenaline and orexin were correlated in the pons and cortex. Transgenic rats had a shorter LORR duration than wild-type rats (36.3 ± 10.4 vs. 46.7 ± 5.2 min, P = 0.002). Noradrenergic activation via intraperitoneal yohimbine prolonged LORR in both genotypes (wild-type: 38.8 ± 4.9 vs. 71.9 ± 15.3 min at 3.3 mg/kg, P = 0.002; transgenic: 28.1 ± 3.9 vs. 71.9 ± 24.8 min, P < 0.001). Noradrenergic deactivation by DSP4 reduced LORR duration (wild-type: 43.3 ± 2.18 vs. 36.4 ± 6.0 min, P = 0.005). Intracerebroventricular orexin (1.0 nmol) shortened LORR (44.0 ± 16.7 vs. 30.1 ± 15.5 min, P = 0.001), but co-administration of selective orexin type 1 receptor antagonist YNT-1310 (100 nmol) counteracted this effect. Notably, orexin or DSP4 reduced LORR duration in wild-type rats but prolonged it in transgenic rats (e.g., wild-type: 40.8 ± 6.2 vs. 32.5 ± 5.3 min with orexin, P = 0.0001; transgenic 28.6 ± 6.2 vs. 42.1 ± 5.6 min, P = 0.0026).ConclusionOrexin-preserved noradrenergic activity supports the typical ketamine-induced sedation profile, highlighting their interactive role in modulating anesthetic depth.

Introduction It has been known that progesterone has central effects, as measured by minimum alveolar concentration in various experimental settings. Previously, we showed that progesterone reduces the sevoflurane requirement for the loss of righting reflex (LORR) using male mice. However, the combination of progesterone and isoflurane has not been studied. Therefore, in this study, we compared the effect of progesterone on anesthetic requirements in a mouse model. Methods Male C57BL/6 mice were treated with either progesterone (75 mg/kg) + olive oil or only olive oil. Animals were studied in closed cylinders supplied with oxygen and isoflurane that rotated four times per minute. Balance disturbance and loss of the righting reflex were counted. The data were analyzed by using a multiple independent variable logistics regression model. Results The concentrations at the onset of balance disturbances, represented by the effective dose 50% (ED50) and effective dose 95% (ED95) of isoflurane, were 0.37% and 0.45% for the control group and 0.34% and 0.41% for the progesterone group, respectively. Similarly, the concentrations for loss of righting reflex (LORR), represented by ED50 and ED95, were 0.55% and 0.62% for the control group and 0.53% and 0.60% for the progesterone group, respectively. Subcutaneous injection of progesterone at a dose of 75 mg/kg significantly reduced the isoflurane requirement for both balance disturbance (p = 0.0022) and LORR (p = 0.0218). Conclusion We conclude that progesterone decreased isoflurane concentration for both balance disturbance and LORR.

Volatile anesthetics are currently believed to cause unconsciousness by acting on one or more molecular targets including neural ion channels, receptors, mitochondria, synaptic proteins, and cytoskeletal proteins. Anesthetic gases including isoflurane bind to cytoskeletal microtubules (MTs) and dampen their quantum optical effects, potentially contributing to causing unconsciousness. This possibility is supported by the finding that taxane chemotherapy consisting of MT-stabilizing drugs reduces the effectiveness of anesthesia during surgery in human cancer patients. In order to experimentally assess the contribution of MTs as functionally relevant targets of volatile anesthetics, we measured latencies to loss of righting reflex (LORR) under 4% isoflurane in male rats injected subcutaneously with vehicle or 0.75 mg/kg of the brain-penetrant MT-stabilizing drug epothilone B (epoB). EpoB-treated rats took an average of 69 s longer to become unconscious as measured by latency to LORR. This was a statistically significant difference corresponding to a standardized mean difference (Cohen's d) of 1.9, indicating a "large" normalized effect size. The effect could not be accounted for by tolerance from repeated exposure to isoflurane. Our results suggest that binding of the anesthetic gas isoflurane to MTs causes unconsciousness and loss of purposeful behavior in rats (and presumably humans and other animals). This finding is predicted by models that posit consciousness as a property of a quantum physical state of neural MTs.

Ciprofol is a novel short-acting intravenous anaesthetic developed in China that is mainly metabolized by cytochrome P450 2B6 (CYP2B6) and uridine diphosphate glucuronosyltransferase 1A9 (UGT1A9). Currently, insufficient evidence is available to support drug‒drug interactions between ciprofol and CYP2B6 inactivators. Here, we established a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method to assess the concentration of ciprofol and investigated the effects of psoralen and clopidogrel on the metabolism of ciprofol in liver microsomes and rats. In rat and human liver microsomes, the median inhibitory concentration (IC50) values of psoralen were 63.31 μmol·L-1 and 34.05 μmol·L-1, respectively, showing mild inhibitory effects on ciprofol metabolism, whereas the IC50 values of clopidogrel were 6.380 μmol·L-1 and 2.565 μmol·L-1, respectively, with moderate inhibitory effects. SD rats were randomly divided into three groups: psoralen (27 mg·kg-1), clopidogrel (7.5 mg·kg-1), and the same volume of 0.5% carboxy methyl cellulose. After 7 days, all rats were injected with 2.4 mg·kg-1 ciprofol. Compared with the control group, the AUC and MRT values of ciprofol in the psoralen and clopidogrel groups were significantly greater, whereas the CL values were significantly lower. In addition, the durations of loss of righting reflex (LORR) in the psoralen and clopidogrel groups were 16.1% and 23.0% longer than that in the control group, respectively. In conclusion, psoralen and clopidogrel inhibit ciprofol metabolism to different degrees and prolong the duration of LORR in rats.

Zolpidem, a non-benzodiazepine hypnotic, is primarily used to treat insomnia. In a previous study, pior treatment with non-benzodiazepine receptor agonists was associated with inflammation. The present study aimed to clarify the association between the effects of zolpidem and inflammation in mice treated with lipopolysaccharide (LPS), a known model of inflammation. We assessed the zolpidem-induced loss of righting reflex (LORR) duration 24 h after LPS treatment in mice. Additionally, the expressions of γ-aminobutyric acid (GABA)A receptor subunit and K+-Cl- cotransporter isoform 2 (KCC2) mRNA in the hippocampus and frontal cortex were examined in LPS-treated mice. Pretreatment with LPS was associated with significantly prolonged duration of zolpidem-induced LORR compared to control mice. This effect was significantly attenuated by administering bicuculline, a GABAA receptor antagonist, or flumazenil, a benzodiazepine receptor antagonist, in LPS-treated mice. Compared to controls, LPS-treated mice showed no significant change in the expression of GABAA receptor subunits in the hippocampus or frontal cortex. Bumetanide, an Na+-K+-2Cl- cotransporter isoform 1 blocker, attenuated the extended duration of zolpidem-induced LORR observed in LPS-treated mice. LPS significantly decreased Kcc2 mRNA expression in the hippocampus and the frontal cortex. These findings suggest that inflammation increases zolpidem-induced LORR, possibly through a reduction in KCC2 expression.

Overdose of carbon dioxide gas (CO₂) is a common euthanasia method for rodents; however, CO₂ exposure activates nociceptors in rats at concentrations equal to or greater than 37% and is reported to be painful in humans at concentrations equal to or greater than 32.5%. Exposure of rats to CO₂ could cause pain before loss of consciousness. We used 2 standardized loss of righting reflex (LORR) methods to identify CO₂ concentrations associated with unconsciousness in Wistar, Long???Evans, and Sprague???Dawley rats (n = 28 animals per strain). A rotating, motorized cylinder was used to test LORR while the rat was being exposed to increasing concentrations of CO₂. LORR was defined based on a 15-second observation period. The 2 methods were 1) a 1-Paw assessment (the righting reflex was considered to be present if one or more paws contacted the cylinder after the rat was positioned in dorsal recumbency), and 2) a 4-Paw assessment (the righting reflex was considered to be present if all 4 paws contacted the cylinder after the rat was positioned in dorsal recumbency). Data were analyzed with Probit regression, and dose-response curves were plotted. 1-Paw EC95 values (CO₂ concentration at which LORR occurred for 95% of the population) were Wistar, 27.2%; Long???Evans, 29.2%; and Sprague???Dawley, 35.0%. 4-Paw EC95 values were Wistar, 26.2%; Long???Evans, 25.9%, and Sprague???Dawley, 31.1%. Sprague???Dawley EC95 values were significantly higher in both 1- and 4-Paw tests as compared with Wistar and Long???Evans rats. No differences were detected between sexes for any strain. The 1-Paw EC95 was significantly higher than the 4-Paw EC95 only for Sprague-Dawley rats. These results suggest that a low number of individual rats from the strains studied may experience pain during CO₂ euthanasia.

Early-life inflammation increases ethanol consumption in adolescent male mice

The role of astrocytic γ-aminobutyric acid in the action of inhalational anesthetics

Surgical incision pain induced an increase in alcohol consumption in mice

The novel non-hallucinogenic compound DM506 (3-methyl-1,2,3,4,5,6-hexahydroazepino[4,5-b]indole) induces sedative- and anxiolytic-like activity in mice by a mechanism involving 5-HT2A receptor activation

Adolescence is a conserved developmental period associated with low alcohol responsivity, which can contribute to heavy drinking and development of an alcohol use disorder (AUD) later in life. To investigate ethanol responsivity between adolescent and adult rats, we developed an ethanol response battery (ERB) to assess acute ethanol responses across cumulative doses of ethanol during the rising phase of the blood ethanol curve. We tested the hypothesis that adolescent male and female rats would exhibit lower ethanol responsivity to a cumulative ethanol challenge relative to adults. Male and female adolescent (postnatal day [P]40) and adult (P85) Wistar rats underwent ERB assessment following consecutive doses of ethanol (i.e., 1.0, 1.0, and 1.0g/kg) to produce cumulative ethanol doses of 0.0, 1.0, 2.0, and 3.0g/kg. The ERB consisted of (1) the 6-point behavioral intoxication rating scale, (2) body temperature assessment, (3) tail blood collection, (4) accelerating rotarod assessment, (5) tilting plane assessment, and (6) loss of righting reflex (LORR) assessment. Across cumulative ethanol doses, adolescent and adult rats evidenced progressive changes in ERB measures. On the ERB, adolescent rats of both sexes evidenced (1) lower intoxication rating, (2) blunted hypothermic responses, particularly in females, (3) longer latencies to fall from the accelerating rotarod, and (4) less tilting plane impairment relative to adults despite comparable BECs. All adult rats, regardless of sex, displayed a LORR at the 3.0g/kg cumulative ethanol dose while among the adolescent rats, only one male rat and no females showed the LORR. These data reveal decreased adolescent ethanol responsivity across body temperature, intoxication, balance, and coordination responses to a cumulative ethanol challenge as assessed using the novel ERB relative to adults. The results of this study suggest that adolescent-specific low ethanol responsivity may contribute to adolescent binge drinking and increased risk for development of an AUD.