Biology subjects

Tyzio, R.

Publications and source records attributed to Tyzio, R..

3 recordsLinked to original sources

bioRxiv2025

Inhibition of oxytocin neurons during key periods of development has long-term behavioural and body composition effects

BackgroundOxytocin (OT) is a key neuromodulator of social behavior in mammals, and accumulating evidence supports the existence of a critical period for OT action during infancy. However, other developmental windows remain poorly explored, and it remains unclear whether OT exert distinct functions depending on the timing of its activity. In this study, we aimed to determine whether specific developmental stages exist during which OT-expressing neurons play a decisive role with long-term consequences. MethodsWe used a chemogenetic approach to transiently inhibit OT-expressing neurons during three postnatal developmental periods: infancy, the juvenile period, and young adulthood in male and female mice. Behavioral and metabolic outcomes were then assessed longitudinally. We also examined the effects of inhibiting OT neurons during late fetal stages and at birth. ResultsSocial memory was consistently impaired in males, regardless of the timing of neuronal inactivation. The most pronounced behavioral effects were observed following inhibition during infancy in both sexes. Metabolically, adult males from all cohorts exhibited increased body weight, whereas increased fat mass and adipocyte size hypertrophy were specifically observed following inhibition during the juvenile period. Notably, inhibition of OT-expressing neurons around the time of birth resulted in delayed parturition and altered neonatal feeding behavior. LimitationsOT-expressing neurons release multiple signaling molecules. However, converging evidence suggests that the observed phenotypes are primarily attributable to OT deficiency. Although this study demonstrates long-term behavioral and metabolic consequences of transient OT neuron inhibition, further experiments are required to elucidate underlying mechanisms and identify additional effects. ConclusionsTransient inhibition of OT-expressing neurons during distinct postnatal developmental periods leads to long-lasting effects on social behavior and metabolism, with outcomes depending on both the timing of inhibition and sex. Furthermore, our findings reveal an unexpected role for fetal/neonatal OT neurons in regulating the timing of birth and early feeding behavior.

neuroscience↗

bioRxiv2023

The oxytocin-modulated brain circuit that synchronizes heart rate with breathing

The variation in heart rate in phase with breathing, called respiratory sinus arrhythmia (RSA), is cardio-protective1,2. RSA amplitude provides an index of health and physical fitness used both clinically, and by the broader population using "smart" watches. Relaxation and positive socio-emotional states can amplify RSA3, yet the underlying mechanism remains largely unknown. Here, we identify a hypothalamus-brainstem neuronal network through which the neuromodulator oxytocin (OT), known for its relaxing and prosocial effects4, amplifies RSA during calming behavior. OT neurons from the caudal paraventricular nucleus in the hypothalamus were found to regulate the activity of a subgroup of inhibitory neurons in the pre-Botzinger complex, the brainstem neuronal group that generates the inspiratory rhythm. Specifically, OT amplifies the inspiratory glycinergic input from pre-Botzinger complex neurons to cardiac-innervating parasympathetic neurons in the nucleus ambiguus. This leads to amplified respiratory modulation of parasympathetic activity to the heart, thereby amplifying RSA. Behaviorally, OT neurons participate in the restoration of RSA amplitude during recovery from stress. This work shows how a central action of OT induces a physiologically beneficial regulation of cardiac activity during a calming behavior, providing a foundation for therapeutic strategies for anxiety disorders and coping with stress. Furthermore, it identifies a phenotypic signature of a subpopulation of neurons controlling RSA, namely pre-Botzinger complex neurons expressing the OT-receptor, enabling the specific modulation of RSA amplitude to resolve its physiological and psychological functions.

neuroscience↗

bioRxiv2020

Acute neonatal oxytocin impacts hippocampal network development and restores adult social memory deficits in a mouse model of autism spectrum disorder.

Oxytocin is a master regulator of the social brain. In some animal models of autism, notably in Magel2 tm1.1Mus-deficient mice, peripheral administration of oxytocin in infancy improves social behaviors until adulthood. However, neither the mechanisms responsible for social deficits nor the mechanisms by which such oxytocin administration has long-term effects are known. Here, we aimed to clarify these oxytocin-dependent mechanisms focusing on social memory performance. We showed that Magel2tm1.1Mus-deficient mice present a deficit in social memory and studied the hippocampal circuits underlying this memory. We showed a co-expression of Magel2 and oxytocin-receptor in the dentate gyrus and CA2/CA3 hippocampal regions. Then, we demonstrated: an increase of the GABAergic activity of CA3-pyramidal cells associated with an increase in the quantity of oxytocin-receptors and of somatostatin interneurons. We also revealed a delay in the GABAergic development sequence in Magel2tm1.1Mus-deficient pups, linked to phosphorylation modifications of KCC2. Above all, we demonstrated the positive effects of subcutaneous administration of oxytocin in the mutant neonates, restoring neuronal alterations and social memory. Although clinical trials are debated, this study highlights the mechanisms by which peripheral oxytocin-administration in neonates impacts the brain and demonstrates the therapeutic value of oxytocin to treat infants with autism spectrum disorders.

neuroscience↗