The carotid body (CB), the main peripheral arterial chemoreceptor, exhibits considerable structural and neurochemical plasticity in response to pathological conditions such as high blood pressure. Previous studies have shown that morphological alterations in the hypertensive CB are characterized by enlarged parenchyma due to cellular hypertrophy and hyperplasia, and vasodilation. To test whether hypertension can also induce neoangiogenesis and modulate its chemosensory function, we examined the immunohistochemical expression of two angiogenic factors, vascular endothelial growth factor (VEGF) and endothelin-1 (ET), and their corresponding receptors in the CB of adult spontaneously hypertensive rats (SHRs), and compared their expression patterns to that of age-matched normotensive Wistar rats (NWR). We found an increased VEGF-A and B, and VEGFR-2 expression in glomus and endothelial cells in the enlarged CB glomeruli of SHRs compared with that in NWR. Conversely, weaker immunoreactivity to VEGFR-1 was detected in cell clusters of the hypertensive CB. The expression of endothelin-converting enzyme 1 and its receptor ETA was higher in a subset of glomus cells in the normotensive CB, while the immunoreactivity to the ETB receptor was enhanced in endothelial cells of CB blood vessels in SHRs. The elevated endothelial expression of VEGF and ET-1 suggests their role as local vascular remodeling factors in the adaptation to hypertension, though their involvement in the cellular rearrangement and modulation of chemosensory function could also be implied.

The bed nucleus of the stria terminalis (BNST) is a heterogeneous and complex limbic forebrain structure, which plays an important role in drug addiction and anxiety. Dynorphin and kappa-opioid receptors (DYN/KOR) comprise a crucial neural system involved in modulating stress-induced drug and alcohol addiction. Previous studies have highlighted the BNST as a brain region with a strong DYN/KOR expression. However, no research has been conducted on the adolescent plasticity of this system. In the present study, we used 20- and 60-day-old Wistar rats to reveal the adolescent dynamics and possible sex differences of the DYN/KOR system in certain BNST nuclei associated with addiction behavior. We found a low expression of DYN in neuronal perikarya and a significant increase in DYN-containing nerve fibers in the lateral posterior and lateral dorsal nuclei of the rat BNST. In addition, an enhanced expression of KORs was observed in the examined BNST subnuclei with some sex differences favoring females, thus highlighting the importance of considering critical developmental differences between sexes in research. The dynamics of the DYN/KOR system observed in this study may help to explain the increased vulnerability of adolescents for developing drug and alcohol addiction.

Adolescence has become an intriguing key period in neurodevelopment when different types of neuroplasticity occur. The bed nucleus of the stria terminalis (BNST) is a part of the limbic system involved in the generation of anxiety, control of social behaviour, and aggression. Because of the increasing frequency of these conditions in adolescence, we set it as a goal to investigate the BNST for neurochemical plasticity during that period. The oxytocin receptor was studied due to its known function in neurodevelopment, anxiety-related behaviours, and social activity. Its expression in preadolescent 20-days-old rats both male and female was compared with adult 60-days-old rats from both sexes too. We found that during adolescence there was a significant down-regulation of these receptors in some subnuclei of BNST. The expression of oxytocin receptors did not differ between sexes. Our results suggest that such a down-regulation in the pubertal period could have effects on the aggressive behaviour and the shifts in the social conduct. The observed neuroplasticity can serve as a fundamental paradigm for further pharmacological research.

The bed nucleus of the stria terminalis (BNST) is a heterogeneous and complex limbic forebrain structure, which plays an important role in drug addiction and anxiety. Dynorphin and kappa opioid receptors (DYN/KOR) is a crucial neural system involved in modulating stress-induced drug and alcohol addiction. Previous studies have highlighted the BNST as a brain region with a strong DYN/KOR expression. However, no research has been done on the adolescent plasticity of this system. In the present study we used 20- and 60-day-old Wistar rats to reveal the adolescent dynamics and possible sex differences of the DYN/KOR system in certain BNST nuclei associated with addiction behavior. We found a low expression of DYN in neuronal perikarya and a significant increase in DYN-containing nerve fibers in the lateral posterior and lateral dorsal nuclei of the rat BNST. In addition, an enhanced expression of KORs was observed in the examined BNST subnuclei with some sex differences favoring females, thus highlighting the importance of considering critical developmental differences between sexes in research. The dynamics of the DYN/KOR system observed in this study may help to explain the increased vulnerability of adolescents for developing drug and alcohol addiction.