Targeting the oxytocin system to ameliorate early life depressive-like behaviors in maternally-separated rats

Effects of double neonatal stress on female rat sexual behaviour

Neonatal stress affects psychological and physiological development and may be associated with affective disorders. The aim was to examine the effects of double neonatal stress (DNS) - a combination of limited bedding and nesting (LBN) and repeated maternal separation (MS) - on the oestrous cycle and sexual behaviour of adult female rats. LBN was achieved by removing part of the wood shavings from the boxes. In the control group, each box was lined with 100 g of wood shavings, while in the experimental group there were only 10 g of wood shavings. MS was performed from P1 (P0 = day of birth) to P15. At P90, the sexual response of females in oestrus was evaluated. Statistical analysis was performed using two-way analysis of variance followed by Tukey's test. The size and profile of the oestrous cycle and the sexual behaviour of female rats submitted to the DNS were considered, as well as the influence of female behaviour on the sexual response of male rats. Female rats submitted to DNS showed a reduction in the lordosis quotient, suggesting a reduction in female receptivity. These rats also showed a reduction in the number of hops and darts, the number of ear wiggles, and the genital exploration time rate, suggesting a reduction in proceptivity. The males that interacted with the females of the DNS group showed a reduction in intromission ratio. Experimental model that mimics neonatal factors that affect adult female sexual response will allow more effective interventions to prevent and treat such changes. In addition, analysis of the female sexual response makes it possible to assess the general state of health and quality of life. In female rats, DNS exerted inhibitory effects on sexual behaviour. LBN was probably the most important factor. In conclusion, combating childhood poverty can be a key measure to prevent problems in the sex life of adults and improve overall health.

Therapeutic uses of oxytocin in stress-related neuropsychiatric disorders

Oxytocin (OXT), produced and secreted in the paraventricular nucleus and supraoptic nucleus of magnocellular and parvocellular neurons. The diverse presence and activity of oxytocin suggests a potential for this neuropeptide in the pathogenesis and treatment of stress-related neuropsychiatric disorders (anxiety, depression and post-traumatic stress disorder (PTSD)). For a more comprehensive understanding of the mechanism of OXT's anti-stress action, the signaling cascade of OXT binding to targeting stress were summarized. Then the advance of OXT treatment in depression, anxiety, PTSD and the major projection region of OXT neuron were discussed. Further, the efficacy of endogenous and exogenous OXT in stress responses were highlighted in this review. To augment the level of OXT in stress-related neuropsychiatric disorders, current biological strategies were summarized to shed a light on the treatment of stress-induced psychiatric disorders. We also conclude some of the major puzzles in the therapeutic uses of OXT in stress-related neuropsychiatric disorders. Although some questions remain to be resolved, OXT has an enormous potential therapeutic use as a hormone that regulates stress responses.

Sex, love and oxytocin: Two metaphors and a molecule

Dozens of studies, most conducted in the last four decades, have implicated oxytocin, as well as vasopressin and their receptors, in processes that mediate selective sociality and the consequences of early experience. Oxytocin is critical for the capacity to experience emotional safety and healthy sexuality. Oxytocin also plays a central role in almost every aspect of physical and mental health, including the coordination of sociality and loving relationships with physiological reactions to challenges across the lifespan. Species, including prairie voles, that share with humans the capacity for selective social bonds have been a particularly rich source of insights into the behavioral importance of peptides. The purpose of this historical review is to describe the discovery of a central role for oxytocin in behavioral interactions associated with love, and in the capacity to use sociality to anticipate and cope with challenges across the lifespan - a process that here is called "sociostasis."

Early Life Stress Induces Different Behaviors in Adolescence and Adulthood May Related With Abnormal Medial Prefrontal Cortex Excitation/Inhibition Balance

Early life stress is thought to be a risk factor for emotional disorders, particularly depression and anxiety. Although the excitation/inhibition (E/I) imbalance has been implicated in neuropsychiatric disorders, whether early life stress affects the E/I balance in the medial prefrontal cortex at various developmental stages is unclear. In this study, rats exposed to maternal separation (MS) that exhibited a well-established early life stress paradigm were used to evaluate the E/I balance in adolescence (postnatal day P43-60) and adulthood (P82-100) by behavior tests, whole-cell recordings, and microdialysis coupled with high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis. First, the behavioral tests revealed that MS induced both anxiety- and depressive-like behaviors in adolescent rats but only depressive-like behavior in adult rats. Second, MS increased the action potential frequency and E/I balance of synaptic transmission onto L5 pyramidal neurons in the prelimbic (PrL) brain region of adolescent rats while decreasing the action potential frequency and E/I balance in adult rats. Finally, MS increases extracellular glutamate levels and decreased the paired-pulse ratio of evoked excitatory postsynaptic currents (EPSCs) of pyramidal neurons in the PrL of adolescent rats. In contrast, MS decreased extracellular glutamate levels and increased the paired-pulse ratio of evoked EPSCs of pyramidal neurons in the PrL of adult rats. The present results reveal a key role of E/I balance in different MS-induced disorders may related to the altered probability of presynaptic glutamate release at different developmental stages.