The coordinated development of the nervous system requires fidelity in the expression of specific genes determining the different neural cell phenotypes. Stem cell fate decisions during neurodevelopment are strictly correlated with their epigenetic status. The epigenetic regulatory processes, such as DNA methylation and histone modifications discussed in this review article, may impact both neural stem cell (NSC) self-renewal and differentiation and thus play an important role in neurodevelopment. At the same time, stem cell decisions regarding fate commitment and differentiation are highly dependent on the temporospatial expression of specific genes contingent on the developmental stage of the nervous system. An interplay between the above, as well as basic cell processes, such as transcription regulation, DNA replication, cell cycle regulation and DNA repair therefore determine the accuracy and function of neuronal connections. This may significantly impact embryonic health and development as well as cognitive processes such as neuroplasticity and memory formation later in the adult.

This study examined low-frequency ultrasonic vocalizations (lUSVs) in rats during two types of sexual interactions: postejaculatory interval (PEI) and barrier-noncontact (NC) test. We report distinct classes of lUSVs that can be assigned to different emotional states; relaxation vs. frustration. Totally flat, 22-kHz calls (Class A), were observed during the relaxation state following ejaculation; characterized by immobilization or grooming during the PEI. On the other hand, two-three component lUSVs (Class B) that start at a higher frequency (45-kHz: flat, upward or short signal) and then shift to 35-23-kHz (mostly to 28-23-kHz), correspond as we assume, to arousal and frustration-active states associated with sniffing a hole or exploration during the NC test. We suggest that momentary, abrupt decreases of arousal during the frustration state correspond to Class B lUSVs. The detailed spectral analysis of the high-frequency component of two-component lUSVs is crucial for establishing the relationship between such lUSVs and the corresponding behavior and emotional states. Our studies indicate that while the two-component Class B 22-kHz lUSVs may relate to the frustration state, a single component, flat, Class A lUSV relates to the relaxation state. The results of these studies support a notion that rats emit distinct vocalization patterns, reflecting their emotional states.

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Introduction: The present study aimed to determine whether the presence of cardiac hypertrophy due to arterial hypertension is associated with a change in the activity of the oxytocinergic system in cardiomyocytes. Material and methods: The experiments were performed on male, spontaneously hypertensive rats (SHR, n = 10) and normotensive Wistar-Kyoto rats (WKY, n = 12). Blood samples were collected from both SHR and WKY animals to asses plasma oxytocin (OT) concentration; the rats were sacrificed by decapitation. Samples of the left and right ventricles were harvested for the analysis of the OT and oxytocin receptor (OTR) protein by ELISA, and OT and OTR mRNA expression by RT-PCR. Immunohistopathological studies were performed to confirm the presence of OTR receptors in the cardiac muscle of the ventricles. Results: Plasma OT concentration did not differ between SHR and WKY rats. In the SHR rats, the expression of OT mRNA and the OT protein level was higher in the left and the right ventricle, while OTR mRNA expression was significantly lower in both the left and the right ventricle. However, the level of OTR protein was higher only in the left ventricle of the SHR rats. The presence of OTR receptors was confirmed by immunohistochemical analysis in the muscle of the right and left ventricle. Conclusions: The presence of arterial hypertension is associated with increased activity of the oxytocinergic system in the heart, especially in the area of the left ventricle. These findings support the important role of this system in the maintenance of cardiovascular homeostasis.