Diabetes-induced changes in the 5-hydroxytryptamine inhibitory receptors involved in the pressor effect elicited by sympathetic stimulation in the pithed rat.

[EN] We investigated the effect of alloxan-induced diabetes on the inhibitory mechanisms of 5-hydroxytryptamine (5-HT) in the pressor responses induced by stimulation of sympathetic vasopressor outflow in pithed rats, and analysed the type and/or subtype of 5-HT receptors involved. 2. Diabetes was induced in male Wistar rats by a single s.c. injection of alloxan, then 4 weeks later, they were anaesthetized, pretreated with atropine and pithed. Electrical stimulation of the sympathetic outflow from the spinal cord (0.1, 0.5, 1 and 5 Hz) resulted in frequency-dependent increases in blood pressure. 3. Intravenous infusions of 5-HT (1-80 microg kg(-1) min(-1)) reduced the pressor effects obtained by electrical stimulation. The 5-HT(1) receptor agonist 5-carboxamidotryptamine, 5-CT (5 microg kg(-1) min(-1)), caused an inhibition of the pressor response, whereas the selective 5-HT(2) receptor agonist, alpha-methyl-5-HT (5 microg kg(-1) min(-1)) and the selective 5-HT(3) receptor agonist, 1-phenylbiguanide (40 microg kg(-1) min(-1)), did not modify the sympathetic pressor responses. 5-HT had no effect on exogenous noradrenaline (NA)-induced pressor responses. 4. The inhibition of electrically induced pressor responses by 5-HT (10 microg kg(-1) min(-1)) was unable to be elicited after i.v. treatment with methiothepin (100 microg kg(-1)) because of the marked inhibition produced by methiothepin alone. The 5-HT-induced inhibition was blocked after i.v. administration of WAY-100,635 (100 microg kg(-1)) and not affected by ritanserin (1 mg kg(-1)), MDL 72222 (2 mg kg(-1)). 5. The selective 5-HT(1A) receptor agonist, 8-hydroxydipropylaminotretalin hydrobromide (8-OH-DPAT) (5-20 microg kg(-1) min(-1)) but neither the rodent 5-HT(1B) receptor agonist, CGS-12066B (5 microg kg(-1) min(-1)), nor the selective nonrodent 5-HT(1B) and 5-HT(1D) receptor agonist, L-694,247 (5 and 40 microg kg(-1) min(-1)), inhibited the electrically induced pressor response. The selective 5-HT(1A) receptor antagonist, WAY-100,635 (100 microg kg(-1)), blocked the inhibition induced by 8-OH-DPAT (10 microg kg(-1) min(-1)). 8-OH-DPAT had no effect on exogenous NA-induced pressor responses. 6. Experimental diabetes produces changes in the inhibitory effect induced by 5-HT on electrically induced sympathetic pressor responses, such that the inhibitory action induced by 5-HT in diabetic pithed rats is mediated by prejunctional 5-HT(1A) receptors

La protéine apparentée à l'hormone parathyroïdienne (PTHrP) dans la biologie de la cellule mésangiale (rôles dans l'inflammation, la croissance et la survie)

La glomérulonéphrite mésangioproliférative (GNMP) se caractérise par une inflammation locale et la prolifération et l apoptose des cellules mésangiales (CM). La protéine apparentée à l hormone parathyroïdienne (PTHrP) a été impliquée dans ces processus dans divers types cellulaires. Nous avons analysé les effets de la PTHrP sur ces processus dans les CM. Nous montrons que la PTHrP majore la prolifération des CM par voie intracrine et diminue leur apoptose par voie paracrine. La PTHrP stimule les voies de l AMPc/PKA et PI3-K/Akt conduisant à l activation du NFkB et à la majoration de la cyclooxygénase-2 (Cox-2). La Cox-2 était responsable de la survie des CM par la PTHrP. Par ailleurs, l IL-1beta et le TNF-alpha majorent l expression de la PTHrP dans les CM, et la PTHrP elle-même induisait l expression de cytokines et chimiokines. L expression des cytokines (IL-17, IL-16), était brève (pic à 2h). L expression des chimiokine (RANTES, MIP-2, TARC et I-TAC) était plus prolongée (4h). Dans un modèle murin de GNMP, la PTHrP était surexprimée à J1 dans les glomérules malades. Elle pourrait contribuer à l inflammation locale, à la prolifération et à la survie des CM.Mesangial proliferative glomerulonephritis (MPGN) is characterized by mesangial cells (MC) inflammation, proliferation and apoptosis. The parathyroid hormone-related protein (PTHrP) is known to influence these processes in many cell types. In this work we analyzed the effects of PTHrP on MC proliferation, apoptosis and inflammation. Our results show that PTHrP induced MC proliferation through the intracrine pathway while it promoted their survival through the paracrine one. PTHrP activating its receptor PTH1R, led to the activation of cAMP/PKA and PI3-K/Akt pathways, which induced NF-kappaB, and upregulated the cyclooxygenase-2 (Cox-2). We have shown that the Cox-2 was responsible of the anti-apoptotic effect of PTHrP on MC. Otherwise, IL-1beta and TNF-alpha importantly upregulated the PTHrP in MC and PTHrP itself led to an overexpression of many cytokines and chemokines. The overexpression of cytokines (IL-17 and IL-16) was brief (2h) while that of chemokines was extended (4h). In a mouse model of MPGN, PTHrP was upregulated in the injured glomeruli at day 1. PTHrP may then contribute to the inflammation, the proliferation and the survival of MC.STRASBOURG-Bib.electronique 063 (674829902) / SudocSudocFranceF

Influencia de la diabetes experimental en respuertas serotonergicas a nivel cardiovascular y renal

Le diabète sucré est une pathologie en progression constante dont la gravité tient à ses complications. Dans cette thèse, nous avons recherché si les réponses cardiovasculaires et rénales à la 5-HT sont altérées au cours d'un diabète sucré expérimental induit chez le rat (alloxan ou streptozotocine). Les effets de la 5-HT sur la neurotransmission sympathique (vasculaire) ou cholinergique (cardiaque), ainsi que sur l'hémodynamique rénale ont été analysés. Les résultats obtenus montrent que:1. Dans le diabète, la 5-HT inhibe la neurotransmission sympathique via des récepteurs 5-HT1A présynaptiques alors que cette inhibition met en jeu les récepteurs 5-HT1D chez le rat normoglycémique. Le monoxyde d'azote contribue à cet effet chez le rat diabétique contrairement aux dérivés de la cyclooxygenase chez le rat normal.2. Dans le diabète, la neurotransmission cholinergique cardiaque est régulée via les récepteurs 5-HT1A/1B (potentialisation) et 5-HT1D (inhibition) pré- et postsynaptiques, alors que chez le rat normoglycémique, seuls les récepteurs présynaptiques 5-HT3 (potentialisation) et 5-HT2 (inhibition) sont impliqués.3. Sur le rein isolé perfusé, la 5-HT induit essentiellement une vasoconstriction via l'activation des récepteurs 5-HT2A, qui est potentialisée dans le diabète. L'activation spécifique des récepteurs 5-HT1A, 5-HT1B et 5-HT2B produit cependant une vasodilatation, non modifiée dans le diabète. 4. Le diabète sucré ne modifie pas l'expression des récepteurs 5-HT1A, 5-HT1B, 5-HT1D, 5-HT2A et 5-HT2B (RT-PCR quantitative) dans les artérioles intrarénales et l'aorte.Ce travail apporte ainsi de nouvelles connaissances quant à la participation des divers récepteurs sérotonergiques dans la régulation des fonctions cardiovasculaires et rénales. Le diabète sucré expérimental modifie les mécanismes sérotonergiques cardiovasculaires et rénaux, en particulier en ce qui concerne les types de récepteurs impliqués, l'intensité des réponses et la participation du NO.Prevalence of diabetes mellitus is increasing throughout the world with high incidence of cardiovascular complications. In this thesis, we looked for the alterations in cardiovascular and renal responses to 5-HT elicited by induction of experimental diabetes mellitus in rats (alloxan or streptozotocin). The effects of 5-HT were analysed on sympathetic (vessels) or cholinergic (heart) neurotransmission, as well as on renal hemodynamic. Present results show that:1. Sympathetic neurotransmission is inhibited by 5-HT via 5-HT1A presynaptic receptors in diabetic rats, with a marked contribution of nitric oxide. In contrast, 5-HT1D receptors are responsible for the inhibition induced by 5-HT in normoglycemic rats and cyclooxygenase products are involved in this response.2. Cholinergique neurotransmission in diabetic rats is potentiated via the activation of 5-HT1A/1B receptors and inhibited via 5-HT1D receptors, both pre- and postsynaptic. This regulation again differs from that found in normoglycemic rats, where potentiation and inhibition occurred via presynaptic 5-HT3 and 5-HT2 receptors, respectively.3. On the isolated perfused kidney, 5-HT elicits vasoconstriction via the activation of 5-HT2A receptors, and this response is increased in diabetic rats. However, the specific activation of 5-HT1A, 5-HT1B and 5-HT2B receptors is also able to elicit renal vasodilatation which was unaffected by diabetes. 4. Diabetes mellitus did not change expression (mRNA, RT-PCR quantitative) of 5-HT1A, 5-HT1B, 5-HT1D, 5-HT2A et 5-HT2B receptors on intrarenal arterioles or aorta.This work therefore provides new data about the contribution of the different 5-HT receptors in the regulation of cardiovascular and renal functions. Moreover, diabetes mellitus modifies these serotonergic mechanisms, particularly in respect with subtypes of 5-HT receptors involved, the level of response and the contribution of NO.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceSpainFRE

Parathyroid Hormone–Related Protein Contributes to Early Healing of Habu Snake Venom–Induced Glomerulonephritis in Mice

International audienceProliferative glomerulonephritis is characterized by local inflammation and mesangial cell deterioration, followed by mesangial proliferation and glomerular healing. Parathyroid hormone-related peptide (PTHrP) is a mesangial cytokine-like growth factor implicated in mesangial proliferation and survival. No data are available about its role in glomerulonephritis. Herein, we analyzed the expression and role of PTHrP in glomerular inflammation and healing in an experimental model of glomerulonephritis induced by i.v. injection of Habu snake venom in mice. The temporal analysis showed marked renal damage in the first days after venom injection and the beginning of recovery within 7 days. Glomerular expression of PTHrP (transcript and protein) was observed in the early phase after venom injection (from day 1 to day 3), along with an inflammatory environment. The inactivation of secreted PTHrP with PTHrP-neutralizing antibody (PTH2E11; 120 μg i.p. daily) reduced the markers of local inflammation (expression of macrophage chemotactic protein-1; regulated upon activation, normal T cell expressed and secreted; cyclooxygenase 2; IL-6; and macrophage infiltration) and abolished the expression of PTHrP itself. Moreover, the glomerular cell proliferation was hampered, and the healing process was prevented on day 7 after venom injection. These results show that PTHrP has antinomic actions in glomerulonephritis, participating in both the proinflammatory condition and the healing process. Our work reveals the essential role of PTHrP in early glomerular repair in an experimental model of glomerulonephritis