Sex-Dependent Social and Repetitive Behavior and Neurochemical Profile in Mouse Model of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by deficits in social interaction, impaired communication, and repetitive behaviors. ASD presents a 3:1 ratio of diagnosed boys and girls, raising the question regarding sexual dimorphic mechanisms underlying ASD symptoms, and their molecular basis. Here, we performed in vivo proton magnetic resonance spectroscopy in juvenile male and female Tsc2+/− mice (an established genetic animal model of ASD). Moreover, behavior and ultrasonic vocalizations during social and repetitive tasks were analyzed. We found significant sexual dimorphisms in the levels of metabolites in the hippocampus and prefrontal cortex. Further, we observed that female mutant animals had a differential social behavior and presented an increase in repetitive behavior. Importantly, while mutant females displayed a more simplified communication during social tasks, mutant males exhibited a similar less complex vocal repertoire but during repetitive tasks. These results hint toward sex-dependent alterations in molecular and metabolic pathways, which can lead to the sexual dimorphic behaviors and communication observed in social and repetitive environments.

Natural Language as a Window into the Subjective Effects and Neurochemistry of Psychedelic Drugs

Psychedelics are drugs capable of eliciting profound alterations in the subjective experience of the users, sometimes with long-lasting consequences. Because of this, psychedelic research tends to focus on human subjects, given their capacity to construct detailed narratives about the contents of their consciousness experiences. In spite of its relevance, the interaction between serotonergic psychedelics and language production is comparatively understudied in the recent literature. This review is focused on two aspects of this interaction: how the acute effects of psychedelic drugs impact on speech organization regardless of its semantic content, and how to characterize the subjective effects of psychedelic drugs by analyzing the semantic content of written retrospective reports. We show that the computational characterization of language production is an emergent powerful tool to predict the therapeutic outcome of individual experiences, relate the effects elicited by psychedelics with those associated with other altered states of consciousness, draw comparisons between the psychedelic state and the symptomatology of certain psychiatric disorders, and investigate the neurochemical profile and mechanism of action of different psychedelic drugs. We conclude that researchers studying psychedelics can considerably expand the range of their potential scientific conclusions by analyzing brief interviews obtained before, during and after the acute effects. Finally, we list a series of questions and open problems that should be addressed to further consolidate this approach.

Perception affects the brain's metabolic response to sensory stimulation

Processing of incoming sensory stimulation triggers an increase of cerebral perfusion and blood oxygenation (neurovascular response) as well as an alteration of the metabolic neurochemical profile (neurometabolic response). Here we show that perceived and unperceived isoluminant chromatic flickering stimuli designed to have similar neurovascular responses as measured by blood oxygenation level dependent functional MRI (BOLD-fMRI) in primary visual cortex (V1) have markedly different neurometabolic responses as measured by functional MRS. In particular, a significant regional buildup of lactate, an index of aerobic glycolysis, and glutamate, an index of malate-aspartate shuttle, occurred in V1 only when the flickering is perceived, without any relation with behavioral or physiological variables. Wheras the BOLD-fMRI signal in V1, a proxy for input to V1, was insensitive to flickering perception by design, the BOLD-fMRI signal in secondary visual areas was larger during perceived than unperceived flickering indicating increased output from V1. These results indicate that the upregulation of energy metabolism induced by visual stimulation depends on the type of information processing taking place in V1, and that 1H-fMRS provides unique information about local input/output balance that is not measured by BOLD-fMRI.

Use of Intranasal Insulin as Neuroprotection From Hyperglycemia in Rat Model of Extremely Preterm Infants

Background: Hyperglycemia is common in extremely preterm infants (EPI) and is a risk factor for increased mortality and morbidity, including abnormal neurodevelopment. Hippocampus-mediated cognitive deficits are common in this population. In a rat model of insulinopenic hyperglycemia, abnormal neurochemistry in the hippocampus was found, with lactate, glutamate (Glu):glutamine (Gln) ratio lower and Phosphorylated Creatinine (PCr):Creatinine (Cr) higher. Intranasal insulin has been shown to improve cognitive function in animal models of Alzheimer’s disease and type 2 diabetes mellitus, as well as in adult human studies of Alzheimer’s disease. No study has previous investigated the use of intranasal insulin on preventing the long-term effects of hyperglycemia in the EPI population. Objective: To determine whether administration of intranasal insulin during early postnatal days would negate the effects of hyperglycemia on the developing hippocampus in neonatal rat model of streptozotocin (STZ)-induced hyperglycemia. Design/Methods: STZ (80mg/kg IP) was injected on postnatal day (P) 2, and littermates in the control group were injected with an equivalent volume of citrate buffer. STZ pups were randomized to intranasal insulin, 3U twice daily from P3-P6 (STZ + INS) or left untreated (STZ). Neurochemical profile (consisting of 20 metabolites, PCr:Cr and Glu:Gln ratios) of the hippocampus was evaluated using ultra-high-field (9.4 T) magnetic resonance spectroscopy (MRS) on P7 (acute effects) and P56 (long-term effects) compared with the control group (CON)(N=6/group). Results: Mean glucose values from P3-P6 were higher in STZ groups (STZ = 279.0 +/- 132.2 mg/dL, STZ+INS = 274.4 +/- 89.5 mg/dL, CONT = 128.4 +/- 15.1 mg/dL). The neurochemical profile was different at both P7 and P56. On P7, compared with the control, the taurine (Tau) was higher in the STZ groups (p = 0.007. At P56, PCr:Cr was higher in the STZ group compared to CONT and STZ+INS groups (p = 0.04). No difference noted between the STZ+INS and CONT groups. No other metabolites were altered. Conclusion: Neonatal hyperglycemia alters the acute and long-term neurochemical profile in the hippocampus of developing rats. The increase in PCr:Cr ratio in the STZ group indicates lower demand for ATP and PCr, secondary to decreased neuronal activity, which has been demonstrated in previous studies. PCr:Cr ratio of the STZ+INS group was no different than control, indicating that intranasal insulin reverses the negative effect on neuronal activity caused by neonatal hyperglycemia.