Morphology of the rat carotid body

The carotid body (CB) is the main peripheral arterial chemoreceptor that registers the levels of pO2, pCO2 and pH in the blood and responds to their changes by regulating breathing. It is strategically located in the bifurcation region of each common carotid artery. The organ consists of "glomera" composed of two cell types, glomus and sustentacular cells, interspersed by blood vessels and nerve bundles, and separated by connective tissue. The neuron-like glomus or type I cells contain numerous cytoplasmic organelles and dense-cored vesicles that store and release neurotransmitters. They form both conventional chemical and electrical synapses between each other and are contacted by peripheral nerve endings of petrosal ganglion afferent neurons. The glial-like sustentacular or type II cells sustain physiologic neurogenesis in the adult CB and are thus supposed to be progenitor cells. This new source of adult stem cells may be potentially useful for tissue repair after injury or for cell therapy against neurodegenerative diseases. The CB is a highly vascularized organ and its intraorgan hemodynamics possibly plays a role in the process of chemoreception. There is also evidence that chronic hypoxia induces marked morphological and neurochemical changes within the CB but the detailed molecular mechanisms by which these affect the hypoxic chemosensitivity still remain to be elucidated. Dysregulation of the CB function is implicated in various physiological and pathophysiological conditions, including ventilatory altitude acclimatization and sleep-disordered breathing. Knowledge of the morphological and functional aspects of the CB will contribute to our better understanding of respiratory homeostasis in health and disease.Biomedical Reviews 2011; 22: 41-55

Interactions between the endogenous cannabinoid system and the peptides of the Tyr-MIF-1 family modulate heat stress-induced analgesia

The present study aimed at evaluating whether an interaction between the endocannabinoid system (ECS) and peptides from the Tyr-MIF-1 family modulates heat stress-induced analgesia. For this purpose, adult male rats were subjected to 1 hour of heat stress. Pain perception was estimated in vivo by Paw pressure test. Immunohistochemical evaluation of CB1 receptors was also performed in the periaqueductal grey (PAG). Our results showed that the application of CB1-receptor agonist anandamide at the end of the stress led to a tendency of decrease in heat-SIA. We also found that each of the four Tyr-MIF-1 peptides interacted with the ECS after acute heat stress, resulting in changes in the PP-thresholds with different direction, degree, and duration. In particular, the administration of MIF-1 and Tyr-K-MIF-1 after CB1-receptor agonist anandamide increased heat stress-induced analgesia (heat-SIA) after the 10th min, while Tyr-MIF-1 and Tyr-W-MIF-1 produced only short-lasting analgesia. CB1-expression in the PAG was also estimated, showing an increase after Tyr-MIF-1 and Tyr-W-MIF-1 administration with anandamide pretreatment, and a decrease after Tyr-W-MIF-1 administration with the CB1-receptor antagonist AM251- or the opioid receptor antagonist naloxone pretreatment. In summary, it can be inferred that under heat stress conditions the peptides from the Tyr-MIF-1 family, interacting with opioid and non-opioid receptors, differently relate with the cannabinoid system and such an interaction modulates heat stress-induced analgesia. It also seems that Tyr-MIF-1 and Tyr-W-MIF-1 have a direct impact on CB1-expression in the PAG, while MIF-1 and Tyr-K-MIF-1 probably act via second messengers or the activation of additional neurotransmitter system(s)

Distribution of serotonin positive mast cells in the intrapulmonary airways of rats

Based on the scarce information about the expression of serotonin by mast cells in normal rat lung, we aimed to describe in detail the distribution of these cells in the wall of bronchi and bronchioles, as well as in the interalveolar septa. To visualize serotonin-positive mast cells a toluidine blue staining was performed immediately after the immunohistochemical staining on the same sections. Thus, we estimated the density of mast cell in different layers of intrapulmonary airways and in alveolar parenchyma. A reduction of mast cell numbers from bronchi to bronchioles, and then to alveolar septa was detected. In conclusion, detailed information about the density of serotonin positive mast cells in the layers of the wall of intrapulmonary airways and alveolar parenchyma is presented. Our findings confirm the role of these cells as one of the main sources of serotonin, which participate in maintaining the homeostasis in the lung

Abstracts Of The Proceedings And The Posters From The Third Scientific Session Of The Medical College Of Varna

October 2-3, 201