Biology subjects

Pocivavsek, A.

Publications and source records attributed to Pocivavsek, A..

8 recordsLinked to original sources

bioRxiv2026

Pregnancy Impacts Maternal Sleep: Focus on Kynurenine Pathway Activation in Female Rats

Study Objectives: Poor maternal sleep is associated with adverse health outcomes for women and their offspring, and perturbations to tryptophan metabolism through the kynurenine pathway (KP) may contribute. Kynurenic acid (KYNA), a neuroactive KP metabolite and endogenous modulator of glutamatergic and cholinergic neurotransmission, is of particular interest because elevated KYNA has been linked to altered sleep-wake behavior and neurodevelopmental outcomes. Because sleep patterns and KP metabolism change during pregnancy, we tested whether pregnancy modifies the effects of kynurenine supplementation on sleep-wake architecture. Methods: To model enhanced KP metabolism, we used the embryonic kynurenine (EKyn) model, in which the maternal diet is supplemented with kynurenine, the initial KP metabolite, during the last week of gestation. Using a within-subject design, we evaluated sleep-wake parameters in pregnant and non-pregnant female rats and assessed KYNA in brain and saliva. Results: Pregnancy increased dark phase NREM and REM sleep in control-fed (ECon) dams, a pattern largely maintained in EKyn dams. However, near parturition, EKyn dams exhibited reduced light phase REM sleep that was not observed in controls. In non-pregnant females, kynurenine supplementation produced a stronger phenotype, consistently reducing light phase REM sleep across treatment days. During pregnancy, kynurenine-associated sleep effects were detectable only when compared to within-subject non-pregnant baseline. Salivary KYNA distinguished kynurenine-fed females from matched controls and correlated with brain KYNA levels. Conclusion: These findings show that pregnancy reshapes sleep-wake architecture and attenuates, but does not eliminate, kynurenine-associated REM sleep disruption, implicating KP metabolism and potentially elevated brain KYNA in maternal sleep regulation.

neuroscience↗

bioRxiv2026

Fragmented sleep during pregnancy induces inflammation and tryptophan-kynurenine pathway metabolism: Importance of elevated fetal brain kynurenic acid

Maternal sleep disturbance is an underrecognized risk factor for adverse offspring outcomes. Prolonged sleep disruption can elicit inflammation, an established risk factor for neuropsychiatric disorders in offspring. Sleep disruptions and inflammation elevate tryptophan degradation via the kynurenine pathway (KP), increasing kynurenic acid (KYNA), a metabolite that inhibits glutamatergic and cholinergic neurotransmission and may thereby affect neurodevelopment. Because KYNA is elevated in the brains of individuals with neurodevelopmental psychotic illnesses, we hypothesize that prenatal KYNA elevation may represent a mechanism link between disturbed maternal sleep, inflammation, and adverse offspring neurodevelopmental health. To test this hypothesis, we employed a novel maternal sleep fragmentation (SleepFrag) paradigm during the final week of gestation. We found that six days of SleepFrag increased maternal plasma inflammatory markers, placental KP metabolism, sex-specific placental inflammation, and fetal brain KP metabolism, including elevated KYNA, without altering KP metabolism in maternal plasma or brain. A parallel embryonic kynurenine (EKyn) model was tested to increase prenatal KP metabolism via a maternal kynurenine-supplemented diet. EKyn increased maternal plasma kynurenine and KYNA, and fetal brain KYNA, with a male-specific increase in fetal brain KYNA-to-kynurenine ratio, despite minimal effects on maternal sleep-wake architecture or inflammation. Together, these findings identify elevated fetal brain KYNA as a convergent outcome through which maternal sleep disruption, inflammation, and KP activation may influence sex-specific neurodevelopment. They further support the EKyn model as a translational tool for isolating consequences of increased prenatal KP metabolism. Protecting maternal sleep and stabilizing fetal brain KYNA levels may promote long-term offspring brain health.

neuroscience↗

bioRxiv2025

Biochemical Regulation of Brain Kynurenic Acid Synthesis and Inhibition in Rats is Sensitive to the Time of Day

Neurochemical imbalances, including elevations of the tryptophan metabolite kynurenic acid (KYNA), an endogenous antagonist of glutamatergic and cholinergic receptors, are linked to cognitive and sleep disturbances in psychiatric and neurocognitive disorders. Therapeutic strategies to reduce brain KYNA by inhibiting kynurenine aminotransferase II (KAT II) are under investigation. However, few studies consider time as a biological variable, despite recent evidence that the time of day can affect brain metabolism and drug effectiveness. Therefore, we explore the hypothesis that KYNA formation and synthesis inhibition change throughout the day. Using rats of both sexes, we measured basal KYNA levels and the effects of kynurenine (100 mg/kg, i.p.), to stimulate de novo KYNA, and/or PF-04859989 (KAT II inhibitor, 30 mg/kg, s.c.), at the beginning of light or dark phases. Microdialysis was used to assess extracellular KYNA in the dorsal hippocampus, and ex vivo assays evaluated KAT enzyme activity in separate animals. Additionally, we examined KYNA levels and the effect of PF-04859989 during acute sleep deprivation in male rats. Regardless of phase, PF-04859989 reduced basal KYNA levels in male but not female rats, yet it reduced kynurenine-stimulated KYNA synthesis in both sexes, demonstrating a context-specific action in female rats. Importantly, we observed a novel effect of phase in males, as kynurenine-induced KYNA synthesis and its inhibition by PF-04859989 were greater during the dark phase than during the light phase. Ex vivo, male KAT II activity was higher, and PF-04859989 was more effective, in the dark than in the light phase, suggesting that properties of the KAT II enzyme itself fluctuate with time of day. Finally, sleep deprivation increased extracellular KYNA levels in the light phase, and PF-04859989 fully ameliorated this increase. Overall, our findings highlight the need to consider time-dependent factors when developing therapies impacting KYNA synthesis. Lay SummaryChanges in brain neurochemistry, including elevations in the tryptophan metabolite kynurenic acid (KYNA), are common in brain disorders that present with sleep disturbances and cognitive deficits as symptoms. KYNA interferes with neurotransmission critical for cognition and sleep, so therapeutic strategies to reduce brain KYNA are being pursued. As recent literature has highlighted the impact of time on brain metabolism and drug efficacy, we, for the first time, explored the hypothesis that KYNA formation and synthesis inhibition change throughout the day. We measured extracellular KYNA levels in the brains of male and female rats and stimulated KYNA synthesis with physiological challenges (exogenous kynurenine, the KYNA bioprecursor, or acute sleep deprivation) and/or inhibited KYNA synthesis pharmacologically (PF-04859989, an inhibitor of the KYNA-synthesizing enzyme kynurenine aminotransferase II (KAT II)). KYNA formation, KAT II enzyme activity, and the effectiveness of PF-04859989 varied throughout the day, highlighting time as a key factor modulating KYNA brain metabolism. PF-04859989 reduced KYNA levels under most conditions. Our findings suggest that the timing of KYNA-targeted treatments should be carefully considered in therapeutic strategies to improve cognition and sleep in brain disorders.

neuroscience↗

bioRxiv2024

Parental kynurenine 3-monooxygenase genotype in mice directs sex-specific behavioral outcomes in offspring

BackgroundDisruptions in brain development can impact behavioral traits and increase the risk of neurodevelopmental conditions such as autism spectrum disorder, attention-deficit/hyperactivity disorder (ADHD), schizophrenia, and bipolar disorder, often in sex-specific ways. Dysregulation of the kynurenine pathway (KP) of tryptophan metabolism has been implicated in cognitive and neurodevelopmental disorders. Increased brain kynurenic acid (KYNA), a neuroactive metabolite implicated in cognition and sleep homeostasis, and variations in the Kmo gene, which encodes kynurenine 3-monooxygenase (KMO), have been identified in these patients. We hypothesize that parental Kmo genetics influence KP biochemistry, sleep behavior and brain energy demands, contributing to impairments in cognition and sleep in offspring through the influence of parental genotype and genetic nurture mechanisms. MethodsA mouse model of partial Kmo deficiency, Kmo heterozygous (HET-Kmo+/-), was used to examine brain KMO activity, KYNA levels, and sleep behavior in HET-Kmo+/- compared to wild-type control (WT-Control) mice. Brain mitochondrial respiration was assessed, and KP metabolites and corticosterone levels were measured in breast milk. Behavioral assessments were conducted on wild-type offspring from two parental groups: i) WT-Control from WT-Control parents, ii) wild-type Kmo (WT-Kmo+/+) from Kmo heterozygous parents (HET-Kmo+/-). All mice were C57Bl/6J background strain. Adult female and male offspring underwent behavioral testing for learning, memory, anxiety-like behavior and sleep-wake patterns. ResultsHET-Kmo+/- mice exhibited reduced brain KMO activity, increased KYNA levels, and disrupted sleep architecture and electroencephalogram (EEG) power spectra. Mitochondrial respiration (Complex I and complex II activity) and electron transport chain protein levels were impaired in the hippocampus of HET-Kmo+/- females. Breast milk from HET-Kmo+/- mothers increased kynurenine exposure during lactation but corticosterone levels were unchanged. Compared to WT-Control offspring, WT-Kmo+/+ females showed impaired spatial learning, heightened anxiety, reduced sleep and abnormal EEG spectral power. WT-Kmo+/+ males had deficits in reversal learning but no sleep disturbances or anxiety-like behaviors. ConclusionsThese findings suggest that Kmo deficiency impacts KP biochemistry, sleep behavior, and brain mitochondrial function. Even though WT-Kmo+/+ inherit identical genetic material as WT-Control, their development might be shaped by the parents physiology, behavior, or metabolic state influenced by their Kmo genotype, leading to phenotypic sex-specific differences in offspring. Plain English summaryInteractions between genetic and environmental factors are carefully regulated during the intricate process of brain development. While genetic information is directly inherited from parents, emerging evidence suggests that parental genetic factors can also shape the environment influencing childrens development in a sex-specific ways. Disruptions in brain development can impact cognitive and behavioral traits and increase the risk of neurodevelopmental conditions such as autism spectrum disorder, attention-deficit/hyperactivity disorder, schizophrenia, and bipolar disorder. This study explored how kynurenine 3-monooxygenase (Kmo) genotype affects female and male mice, focusing on potential sex-specific behavioral changes in offspring born to parents with a genetic disruption in Kmo. We found that female and male mice with partial Kmo deficiency experienced reduced sleep and increased sleep pressure. In female mice, Kmo deficiency impaired mitochondrial energy production in the brain. We also observed alterations in tryptophan metabolism and nutrient composition in the breast milk of Kmo-deficient females. In adult offspring born to Kmo-deficient parents, females exhibited learning difficulties, heightened anxiety-like behaviors, and sleep disturbances. In contrast, male offspring showed mild cognitive impairments but no major sleep issues. These findings highlight that parental Kmo genotype can influence sex differences in cognitive and sleep-related behaviors in offspring. This underscores the importance of considering parental genetic factors when studying neurodevelopmental disorders and associated behavioral outcomes. HighlightsO_LIMice with a partial Kmo deficiency, Kmo heterozygous (HET-Kmo+/-), were used to evaluate the impact of parental Kmo genetics on kynurenine pathway biochemistry, brain mitochondrial function, sleep patterns, and cognitive performance. C_LIO_LIFemale and male HET-Kmo+/- mice exhibited elevated brain KYNA levels and had reduced sleep, prolonged wakefulness, and altered spectra power during sleep. In HET-Kmo+/- females, hippocampal mitochondrial respiration and electron transport chain protein levels were significantly altered. Breast milk from HET-Kmo+/- females increased kynurenine exposure during lactation to offspring, including their wild-type (WT-Kmo+/+) offspring. C_LIO_LISex differences were observed in learning and memory, anxiety-like behavior, and sleep-wake patterns between WT-Control, from wild-type parents, and WT-Kmo+/+ offspring from HET-Kmo+/- parents. Female WT-Kmo+/+ offspring had impaired spatial learning, increased anxiety-like behavior, reduced sleep, but elevated delta power during sleep. Male WT-Kmo+/+ offspring exhibited deficits in reversal learning only and not sleep impairments. C_LI

neuroscience↗

bioRxiv2023

The sleep quality- and myopia-linked PDE11A-Y727C variant impacts neural physiology by reducing catalytic activity and altering subcellular compartmentalization of the enzyme

Recently, a Y727C variant in the dual-specific 3,5-cyclic nucleotide phosphodiesterase 11A (PDE11A-Y727C) was linked to increased sleep quality and reduced myopia risk in humans. Given the well-established role that the PDE11 substrates cAMP and cGMP play in eye physiology and sleep, we determined if 1) PDE11A protein is expressed in the retina or other eye segments in mouse, 2) PDE11A-Y7272C affects catalytic activity and/or subcellular compartmentalization more so than the nearby suicide-associated PDE11A-M878V variant, and 3) Pde11a deletion alters eye growth or sleep quality in male and female mice. Western blots show distinct protein expression of PDE11A4, but not PDE11A1-3, in eyes of Pde11a WT--but not KO mice--that vary by eye segment and age. In HT22 and COS-1 cells, PDE11A4-Y727C reduces PDE11A4 catalytic activity far more than PDE11A4-M878V, with both variants reducing PDE11A4-cAMP more so than PDE11A4-cGMP activity. Despite this, Pde11a deletion does not alter age-related changes in retinal or lens thickness, axial length, nor vitreous or anterior chamber depth. Further, Pde11a deletion only minimally changes refractive error and sleep quality. That said, both variants also dramatically alter the subcellular compartmentalization of human and mouse PDE11A4, an effect occurring independently of dephosphorylating PDE11A4-S117/S124 or phosphorylating PDE11A4-S162. Rather, re-compartmentalization of PDE11A4-Y727C is due to the loss of the tyrosine changing how PDE11A4 is packaged/repackaged via the trans-Golgi network. Therefore, the protective impact of the Y727C variant may reflect a gain-of-function (e.g., PDE11A4 displacing another PDE) that warrants further investigation in the context of reversing/preventing sleep disturbances or myopia.

neuroscience↗

bioRxiv2022

Reducing brain kynurenic acid synthesis precludes kynurenine-induced sleep disturbances

Patients with neurocognitive disorders often battle sleep disturbances. Kynurenic acid (KYNA) is a tryptophan metabolite of the kynurenine pathway implicated in the pathology of these illnesses. Modest increases in KYNA, an antagonist at glutamatergic and cholinergic receptors, result in cognitive impairments and sleep dysfunction. We explored the hypothesis that inhibition of the KYNA synthesizing enzyme, kynurenine aminotransferase II (KAT II), may alleviate sleep disturbances. At the start of the light phase, adult male and female Wistar rats received systemic injections of either i) vehicle, ii) kynurenine (100mg/kg; i.p.), iii) the KAT II inhibitor, PF-04859989 (30 mg/kg; s.c.), or iv) PF-04859989 and kynurenine in combination. Kynurenine and KYNA levels were evaluated in the plasma and brain. Separate animals were implanted with electroencephalogram (EEG) and electromyogram (EMG) telemetry devices to record polysomnography and evaluate vigilance states wake, rapid eye movement sleep (REMS) and non-REM sleep (NREMS) following each treatment. Kynurenine challenge increased brain KYNA and resulted in reduced REMS duration, NREMS delta power and sleep spindles. PF-04859989 reduced brain KYNA formation when given prior to kynurenine, prevented disturbances in REM sleep and sleep spindles, and enhanced NREM sleep. Our findings suggest that reducing KYNA in conditions where the kynurenine pathway is activated may serve as a potential strategy for improving sleep dynamics.

neuroscience↗

bioRxiv2022

Kynurenine aminotransferase II inhibition promotes sleep and rescues impairments induced by neurodevelopmental insult

Dysregulated sleep is commonly reported in individuals with neuropsychiatric disorders, including schizophrenia (SCZ) and bipolar disorder (BPD). Physiology and pathogenesis of these disorders points to aberrant metabolism, during neurodevelopment and adulthood, of tryptophan via the kynurenine pathway (KP). Kynurenic acid (KYNA), a neuroactive KP metabolite derived from its precursor kynurenine by kynurenine aminotransferase II (KAT II), is increased in the brains of individuals with SCZ and BPD. We hypothesize that elevated KYNA, an inhibitor of glutamatergic and cholinergic neurotransmission, contributes to sleep dysfunction. Employing the embryonic kynurenine (EKyn) paradigm to elevate KYNA in the fetal brain, we presently examined whether reducing KYNA in adulthood by pharmacologically inhibiting KAT II would improve sleep quality. Pregnant Wistar rats were fed either kynurenine (100 mg/day) (EKyn) or control wet mash (ECon) from embryonic day (ED) 15 to ED 22. In adulthood, male and female offspring were implanted with devices to record electroencephalogram (EEG) and electromyogram (EMG) telemetrically for continuous sleep-wake data acquisition. Each subject was treated with either vehicle or PF-04859989 (30 mg/kg, s.c.), an irreversible KAT II inhibitor, at zeitgeber time (ZT) 0 or ZT 12. KAT II inhibitor improved sleep architecture maintaining entrainment of the light-dark cycle; ZT 0 treatment with PF-04859989 induced transient improvements in rapid eye movement (REM) and non-REM (NREM) during the immediate light phase, while the impact of ZT 12 treatment was delayed until the subsequent light phase. PF-04859989 administration at ZT 0 enhanced NREM delta spectral power and reduced activity and body temperature. In conclusion, reducing de novo KYNA production alleviated sleep disturbances and increased sleep quality in EKyn, while also improving sleep outcomes in ECon offspring. Our findings place attention on KAT II inhibition as a novel mechanistic approach to treating disrupted sleep behavior with potential translational implications for patients with neurodevelopmental and neuropsychiatric disorders.

neuroscience↗

bioRxiv2021

Estradiol Influences Adenosinergic Signaling and NREM Sleep Need in Adult Female Rats

Studies report estradiol (E2) suppresses sleep in females; however, the mechanisms of E2 action remain largely undetermined. Our previous findings suggest that the median preoptic nucleus (MnPO) is a key nexus for E2 action on sleep. Here, using behavioral, neurochemical and pharmacological approaches, we investigated whether E2 influenced the sleep homeostat as well as adenosinergic signaling in the MnPO of adult female rats. During the Light Phase, where rats accumulate the majority of sleep, E2 markedly reduced NREM-SWA (a measure of the homeostatic sleep need). Following 6-hours of sleep deprivation, levels of NREM-SWA were significantly increased compared to baseline sleep. However, the NREM-SWA levels were not different between E2 and control treatment despite a significant increase in wake at the expense of NREM sleep. Analysis of NREM-SWA differences between baseline and recovery sleep following sleep deprivation demonstrated that E2 induced a 2-fold increase in delta power compared to controls suggesting that E2 significantly expanded the dynamic range for the sleep homeostat. Correlated with E2-induced changes in physiological markers of homeostatic sleep was a marked increase in extracellular adenosine (a molecular marker of homeostatic sleep need) during unrestricted and recovery sleep following a 6-hour deprivation. Additionally, E2 blocked the ability of an adenosine A2A receptor agonist (CGS-21680) to increase NREM sleep compared to controls. Thus, taken together, the findings that E2 increased extracellular adenosine content, while blocking A2A signaling in the MnPO suggests a potential mechanism for how estrogens impact sleep in the female brain. Statement of SignificanceWhile gonadal steroids and gender are implicated as risk factors for sleep disruptions and insomnia, the relationship between ovarian steroids and sleep is poorly understood. Understanding the mechanisms through which estradiol (E2) is working to influence sleep-wake behavior is a critical first step toward a better understanding of the role of estrogens in sleep pathologies. Using a rodent model, the current study presents novel findings suggesting that estradiol (E2) is influencing adenosinergic actions in the MnPO. The ability of E2 to attenuate the local effects of the A2A receptors in the MnPO suggests that E2 modulation of A2A receptor signaling may underlie estrogenic suppression of sleep behavior as well as changes in homeostatic sleep need.

neuroscience↗