Vasopressin (VP) and VP-like neuropeptides are evolutionarily stable peptides found in all vertebrate species. In non-mammalian vertebrates, vasotocin (VT) plays a role similar to mammalian VP, whereas mesotocin and isotocin are functionally similar to mammalian oxytocin (OT). Here, we review the involvement of VP in brain circuits, synaptic plasticity, evolution, and function, highlighting the role of VP in social behavior. In all studied species, VP is encoded on chromosome 20p13, and in mammals, VP is produced in specific hypothalamic nuclei and released by the posterior pituitary. The role of VP is mediated by the stimulation of the V1a, V1b, and V2 receptors as well as the oxytocinergic and purinergic receptors. VT and VP functions are usually related to osmotic and cardiovascular homeostasis when acting peripherally. However, these neuropeptides are also critically involved in the central modulation of social behavior displays, such as pairing recognition, pair-bonding, social memory, sexual behavior, parental care, and maternal and aggressive behavior. Evidence suggests that these effects are primarily mediated by V1a receptor in specific brain circuits that provide important information for the onset and control of social behaviors in normal and pathological conditions.

Social relations are built and maintained from the interaction among individuals. The oxytocin (OT), vasopressin (VP), estrogen, dopamine, and their receptors are involved in the modulation of sexual behavior in females. This study aimed to analyze the impact of OT gene knockout (OTKO) on sexual behavior and the gene expression of oxytocin (OTR), estrogen alpha (ERα), estrogen beta (ERβ), vasopressin (VR), and dopamine (DR) receptors in the olfactory bulb (OB), prefrontal cortex (PFC), hippocampus (HPC), and hypothalamus (HPT), as well as in the synthesis of VP in the HPT of female mice. Wild-type (WT) littermates were used for comparisons. The DNAs were synthesized by polymerase chain reaction and the gene expression was calculated with the 2 formula. Our results showed that the absence of OT caused an increase in the frequency and duration of non-receptive postures and a decrease in receptive postures in the OTKO. OTKO females showed a significant decrease in the gene expression of OTR in the HPC, VR in the HPT, and ERα and ERβ in the PFC. There was no significant difference in the gene expression of DR of OTKO. However, OTKO showed an increased gene expression of VR in the HPC. There is no significant difference in VP mRNA synthesis in the HPT between OTKO and WT. Our findings demonstrate that the absence of OT leads to significant changes in the expression of the studied genes (OTR, ERα, ERβ, VR), and these changes may contribute to the decreased sexual behavior observed in OTKO females.

No abstract

Objective: The purpose of the present study was to evaluate the association between the 5-HTTLPR and 5-HTTVNTR polymorphisms in the serotonin transporter gene (SLC6A4) in Brazilian women with diagnosed postpartum depression (PPD) and the presence of depressive symptoms. Method: The cohort consisted of 128 white women who were characterized based on skin color and morphological characteristics. The Beck Depression Inventory was used to diagnose PPD and to score the depressive symptoms. The 5-HTTLPR and 5-HTTVNTR polymorphisms were analyzed by PCR-based methods. Results: No association was observed between the PPD diagnosis and either the 5-HTTLPR (p = 0.48) or the 5-HTTVNTR (p = 0.77) polymorphism. When the polymorphisms were analyzed together with haplotype data, the analyses demonstrated that women carriers of the L-12/L-12 diplotype have lower Beck Depression Inventory scores than women carrying other diplotypes (p = 0.04). Discussion: Few studies have investigated the association of SLC6A4 polymorphisms with PPD, and the role of 5-HTTLPR and 5-HTTVNTR polymorphisms in PPD susceptibility has not been established to date. Therefore, our findings link the haplotypes of these two variants with depression symptoms, thereby contributing to our understanding of PPD susceptibility.