Viszcero- és szomatoszenzoros agypályák neuroanatómiai és neurokémiai vizsgálata = Neuroanatomical and neurochemical studies on viscero- and somatosensory neuronal pathways

A program célkitűzése különböző agypályák neuroanatómiai és neurokémiai vizsgálata, valamint 10 fiatal agykutató (PhD, TDK) képzése volt. A kutatási terv célkitűzéseit megvalósítottuk: 3 hallgató készítette el PhD téziseit. Az alábbi eredményeket 18 dolgozatban közöltük (impakt faktor: 101.077) és 19 kongresszusi előadásban/poszteren ismertettük. 1) Elsőként lokalizáltuk a vestibularis stressz pályáját. 2) Új termoszenzitív agypálya leírása. 3) A hibernáció folyamata (6 fázis) alatt bekövetkező funkcionális morfológiai változások "system neuroscience" típusú értékelése (hely, idő, működés rendszerfüggő értékelése). 4) A trigeminális fájdalom okozta stressz pályájának finom topográfiája. 5) A prefrontális agykéregnek a gyomor működést befolyásoló poliszinaptikus (prelimbic-cingulate-amygdala-vagus) pálya topográfiai feldolgozása. 6) Elsőként igazoltuk, hogy a patkány és emberi hippocampus CA2 area idegsejtjei vasopressin 1b receptort szintetizálnak, aminek a szociális viselkedésben és agresszivitásban van szerepe. 7) Kimutattuk a táplálékfelvételben szerepet vivő nucleus arcuatus neuronok direkt kapcsolatát a nyúlt- és gerincvelői preganglionáris idegsejtekkel. 8) Retrograd transz-szinaptikus pályajelöléssel lokalizáltuk a gyomrot és a duodenumot szelektive beidegző spinalis, agytörzsi és hypothalamikus neuronokat. 9) Felderítettük a sacralis gerincvelőben levő és ide érkező idegrostok kémiai karakterét, végződésük térbeli rendjét és e terület speciális ependyma strukturáját. | Neuroanatomical and neurochemical studies on viscerosensory and visceromotor pathways constituted the major goals of this project, in addition to the training of 10 PhD fellows and medical students for basic neuroscience. The program of the project has been completed. The results have been published in 18 manuscripts (impact factor: 101.077) and presented in 19 lectures or posters. Three fellows compiled their PhD theses. Major new findings: 1) First description of the pathway of the vestibular stress. 2) Demonstration of the existence of a brainstem-preoptic thermosensitive pathway. 3) Functional anatomical evaluation of the activity of central regulatory mechanisms during the 6 phases of hibernation. 4) Localization of the pain-related trigemino-hypothalamic pathway. 5) Description of the medial prefrontal-amygdala-vagus neuronal circuit that may influence gastric activities. 6) First demonstration of the synthesis of vasopressin 1b receptors in rat and human CA2 hippocampal neurons. 7) Demonstration of hypothalamic arcuate nucleus projections to medullary and spinal preganglionic neurons. 8) Localization of spinal, brainstem and hypothalamic neurons, which participate in the selective innervations of the stomach and the duodenum. 9) The chemical character, the spatial arrangement of nerve fibers in the sacral spinal cord, as well as the special, labyrinth-like structure of the sacral ependyma has been determined

Nerve stretch injury induced pain pattern and changes in sensory ganglia in a clinically relevant model of limb-lengthening in rabbits.

We used a model of tibial lengthening in rabbits to study the postoperative pain pattern during limb-lengthening and morphological changes in the dorsal root ganglia (DRG), including alteration of substance P (SP) expression. Four groups of animals (naive; OG: osteotomised only group; SDG/FDG: slow/fast distraction groups, with 1 mm/3 mm lengthening a day, respectively) were used. Signs of increasing postoperative pain were detected until the 10(th) postoperative day in OG/SDG/FDG, then they decreased in OG but remained higher in SDG/FDG until the distraction finished, suggesting that the pain response is based mainly on surgical trauma until the 10(th) day, while the lengthening extended its duration and increased its intensity. The only morphological change observed in the DRGs was the presence of large vacuoles in some large neurons of OG/SDG/FDG. Cell size analysis of the S1 DRGs showed no cell loss in any of the three groups; a significant increase in the number of SP-positive large DRG cells in the OG; and a significant decrease in the number of SP-immunoreactive small DRG neurons in the SDG/FDG. Faster and larger distraction resulted in more severe signs of pain sensation, and further reduced the number of SP-positive small cells, compared to slow distraction

Similarity and dissimilarity in antinociceptive effects of dipeptidyl-peptidase 4 inhibitors, Diprotin A and vildagliptin in rat inflammatory pain models following spinal administration.

Dipeptidyl-peptidase 4 (DPP4) enzyme is involved in the degradation of many biologically active peptides including opioids. Its role in pain transmission is poorly elucidated. Recently we reported on the spinal antihyperalgesic effects of DPP4 inhibitors, Ile-Pro-Ile (Diprotin A) and vildagliptin in carrageenan-evoked acute inflammatory pain in rats. The present study investigated the effects of intrathecal (it.) diprotin A and vildagliptin in Complete Freund's Adjuvant- (CFA) and formalin induced pain in rats. The former assay can model the subchronic inflammatory pain condition and the later one reflects both acute tonic and inflammatory pain conditions. The involvement of opioid receptor (OR) subtypes, Y1-, and GLP1 receptors were also investigated. In CFA pain model it. diprotin A or vildagliptin dose-dependently inhibits hyperalgesia in ipsilateral while has no effect in contralateral paws. The peak effect was achieved 30 min following drug administration which was used for further analysis. Both compounds showed naltrexone reversible antihyperalgesia. Co-administration of OR-subtype-selective antagonists with diprotin A and vildagliptin revealed involvement of μ and δ > μ opioid receptors, respectively. Co-administered Y1 but not GLP1 receptor antagonists reversed the antihyperalgesic action of both DPP4 inhibitors. In touch-hypersensitivity both compounds were ineffective. In formalin test only diprotin A showed μ and δ OR-mediated antinociception and only in the 2nd phase. This effect was Y1 or GLP-1 receptor antagonist insensitive. In conclusion, diprotin A and vildagliptin display antinociception of different mechanisms of action in subchronic inflammatory pain. Furthermore, the spinal pain relay points of inflammatory pain of acute or subchronic conditions were more effectively affected by diprotin A than vildagliptin which needs future elucidation

Pathology and glia type specific changes of the DPP4 activity in the spinal cord contributes to the development and maintenance of hyperalgesia and shapes opioid signalling in chronic pain states

Altered pain sensations such as hyperalgesia and allodynia are characteristic features of various chronic pain states, and remain difficult to treat. We have shown previously that spinal application of dipeptidyl peptidase 4 (DPP4) enzyme inhibitors results in a strong antihyperalgesic effect during inflammatory pain states. In this study we observed a low level of mRNA for DPP4 in the rat spinal dorsal horn in physiological conditions, which did not change significantly either in carrageenan-induced inflammatory or partial nerve ligation-generated neuropathic states. Although DPP4 protein was detected in neurons, astrocytes and microglia in naïve animals its expression significantly increased in astrocytes during inflammation and in microglia in neuropathic conditions. Intrathecal application of two DPP4 inhibitors the tripeptide isoleucin-prolin-isoleucin (IPI) and the antidiabetic drug vildagliptin resulted in robust opioid-dependent antihyperalgesic effect during inflammation and an opioid-independent effect in the Seltzer model. The opioid-mediated antihyperalgesic effect of IPI was exclusively related to mu-opioid receptors, while vildagliptin affected mainly delta-receptor activity, although mu- and kappa-receptors were also involved. Our results suggest a pathology and glia type specific changes of the DPP4 activity in the spinal cord which contributes to the development and maintenance of hyperalgesia and shapes opioid signalling

Unique, Specific CART Receptor-Independent Regulatory Mechanism of CART(55-102) Peptide in Spinal Nociceptive Transmission and Its Relation to Dipeptidyl-Peptidase 4 (DDP4)

Cocaine- and amphetamine-regulated transcript (CART) peptides are involved in several physiological and pathological processes, but their mechanism of action is unrevealed due to the lack of identified receptor(s). We provided evidence for the antihyperalgesic effect of CART(55-102) by inhibiting dipeptidyl-peptidase 4 (DPP4) in astrocytes and consequently reducing neuroinflammation in the rat spinal dorsal horn in a carrageenan-evoked inflammation model. Both naturally occurring CART(55-102) and CART(62-102) peptides are present in the spinal cord. CART(55-102) is not involved in acute nociception but regulates spinal pain transmission during peripheral inflammation. While the full-length peptide with a globular motif contributes to hyperalgesia, its N-terminal inhibits this process. Although the anti-hyperalgesic effects of CART(55-102), CART(55-76), and CART(62-76) are blocked by opioid receptor antagonists in our inflammatory models, but not in neuropathic Seltzer model, none of them bind to any opioid or G-protein coupled receptors. DPP4 interacts with Toll-like receptor 4 (TLR4) signalling in spinal astrocytes and enhances the TLR4-induced expression of interleukin-6 and tumour necrosis factor alpha contributing to inflammatory pain. Depending on the state of inflammation, CART(55-102) is processed in the spinal cord, resulting in the generation of biologically active isoleucine-proline-isoleucine (IPI) tripeptide, which inhibits DPP4, leading to significantly decreased glia-derived cytokine production and hyperalgesia

Unique, Specific CART Receptor-Independent Regulatory Mechanism of CART(55-102) Peptide in Spinal Nociceptive Transmission and Its Relation to Dipeptidyl-Peptidase 4 (DDP4)

Cocaine- and amphetamine-regulated transcript (CART) peptides are involved in several physiological and pathological processes, but their mechanism of action is unrevealed due to the lack of identified receptor(s). We provided evidence for the antihyperalgesic effect of CART(55-102) by inhibiting dipeptidyl-peptidase 4 (DPP4) in astrocytes and consequently reducing neuroinflammation in the rat spinal dorsal horn in a carrageenan-evoked inflammation model. Both naturally occurring CART(55-102) and CART(62-102) peptides are present in the spinal cord. CART(55-102) is not involved in acute nociception but regulates spinal pain transmission during peripheral inflammation. While the full-length peptide with a globular motif contributes to hyperalgesia, its N-terminal inhibits this process. Although the anti-hyperalgesic effects of CART(55-102), CART(55-76), and CART(62-76) are blocked by opioid receptor antagonists in our inflammatory models, but not in neuropathic Seltzer model, none of them bind to any opioid or G-protein coupled receptors. DPP4 interacts with Toll-like receptor 4 (TLR4) signalling in spinal astrocytes and enhances the TLR4-induced expression of interleukin-6 and tumour necrosis factor alpha contributing to inflammatory pain. Depending on the state of inflammation, CART(55-102) is processed in the spinal cord, resulting in the generation of biologically active isoleucine-proline-isoleucine (IPI) tripeptide, which inhibits DPP4, leading to significantly decreased glia-derived cytokine production and hyperalgesia

Unique, Specific CART Receptor-Independent Regulatory Mechanism of CART(55-102) Peptide in Spinal Nociceptive Transmission and Its Relation to Dipeptidyl-Peptidase 4 (DDP4)

Cocaine- and amphetamine-regulated transcript (CART) peptides are involved in several physiological and pathological processes, but their mechanism of action is unrevealed due to the lack of identified receptor(s). We provided evidence for the antihyperalgesic effect of CART(55-102) by inhibiting dipeptidyl-peptidase 4 (DPP4) in astrocytes and consequently reducing neuroinflammation in the rat spinal dorsal horn in a carrageenan-evoked inflammation model. Both naturally occurring CART(55-102) and CART(62-102) peptides are present in the spinal cord. CART(55-102) is not involved in acute nociception but regulates spinal pain transmission during peripheral inflammation. While the full-length peptide with a globular motif contributes to hyperalgesia, its N-terminal inhibits this process. Although the anti-hyperalgesic effects of CART(55-102), CART(55-76), and CART(62-76) are blocked by opioid receptor antagonists in our inflammatory models, but not in neuropathic Seltzer model, none of them bind to any opioid or G-protein coupled receptors. DPP4 interacts with Toll-like receptor 4 (TLR4) signalling in spinal astrocytes and enhances the TLR4-induced expression of interleukin-6 and tumour necrosis factor alpha contributing to inflammatory pain. Depending on the state of inflammation, CART(55-102) is processed in the spinal cord, resulting in the generation of biologically active isoleucine-proline-isoleucine (IPI) tripeptide, which inhibits DPP4, leading to significantly decreased glia-derived cytokine production and hyperalgesia