Plasma Extravasation In Rat Skin Research Articles

Isoprostanes induce plasma extravasation in rat skin

Isoprostane E 2 (8-iso PGE) and isoprostane F 2α (8-iso PGF) contribute to numerous vascular, proinflammatory, and nociceptive functions. The underlying mechanisms for many of their actions are still under investigation. We examined the ability of isoprostanes to promote cutaneous inflammation using the Evan’s blue dye method. Our data show that 4 μg subcutaneously (s.c.) injected 8-iso PGE or 8-iso PGF induced plasma extravasation in glabrous rat skin. Dye extravasation was also elicited in hairy skin after injections of 8-iso PGE, but not after 8-iso PGF. Isoprostane-evoked dye extravasation can be reduced by pretreatment with both the S+ and R− isomers of the cyclooxygenase (COX)-inhibitor ibuprofen (30 mg/kg intraperitoneally), indicating perhaps a nonspecific inhibition; pretreatment with ketorolac (1 and 10 mg/kg i.v.) was without effect. Unlike isoprostane-induced cutaneous nociceptor sensitization, which is blocked in a stereospecific and dose-dependent manner by COX-inhibitors, the effect of these drugs on isoprostane-induced cutaneous plasma extravasation is less consistent. We conclude that at least a large component of the isoprostane effect on cutaneous plasma extravasation is COX-independent.

Involvement of vanilloid receptors and purinoceptors in the Phoneutria nigriventer spider venom-induced plasma extravasation in rat skin

Phoneutria nigriventer venom causes stimulation of capsaicin-sensitive primary afferent neurons in the rat dorsal skin, leading to neurogenic plasma protein extravasation due to the release of tachykinin NK 1 receptor agonist. In this study we further investigated the mechanisms involved in the venom-induced activation of capsaicin-sensitive primary afferent neurons. The plasma extravasation in response to venom intradermally injected was measured in Wistar rats as the local accumulation of i.v. injected 125I-labelled human serum albumin into skin sites. The tachykinin NK 1 receptor agonist, d-Ala-[ l-Pro 9,Me-Leu 8]substance P-(7–11) (GR73632; 10–100 pmol/site), induced a significant plasma leakage that was abolished by the selective tachykinin NK 1 receptor antagonist, ( S)-1-[2-[3-(3,4-dichlorphenyl)-1 (3-isopropoxyphenylacetyl) piperidin-3-yl] ethyl]-4-phenyl-1 azaniabicyclo [2.2.2]octane chloride (SR140333; 1 nmol/site), whereas the leakage after venom (1–10 μg/site) was significantly inhibited (but not abolished) by SR140333. The calcitonin gene-related peptide (CGRP) receptor antagonist, CGRP-(8–37), failed to further reduce the residual plasma extravasation induced by venom plus SR140333. The μ-opioid receptor agonist, [ d-Ala 2,Me-Phe 4,Gly-ol 5]enkephalin (DAMGO), and the local anaesthetic, lignocaine, had no effect on the venom-induced plasma extravasation. Similarly, the L-, N- and P/Q-type voltage-sensitive Ca 2+ channel blockers (verapamil, ω-conotoxin MVIIA and MVIIC, respectively) as well as the Na + channel blockers, tetrodotoxin and carbamazepine, had no effect on the venom-induced effect. Neither the systemic treatment nor the local injection of ruthenium red prevented the venom-induced plasma extravasation. However, the vanilloid receptor antagonist, N-[2-(4-chlorophenyl) ethyl]-1,3,4,5-tetrahydro-7,8-dihydroxy-2 H-2-benzazepine-2-carbothioamide (capsazepine; 120 μmol/kg, i.v.), reduced by 48% ( P<0.05) the venom (10 μg/site)-induced plasma extravasation. A significant inhibitory effect was also observed with the P 2 purinoceptor agonists, adenosine 5′-triphosphate (ATP; 10 and 30 nmol/site) and adenosine 5′-diphosphate (ADP; 10 nmol/site). The involvement of histamine and/or 5-hydroxytryptamine (5-HT) in the venom-induced plasma extravasation was ruled out since neither histamine and 5-HT receptor antagonists nor depletion of mast cells by compound 48/80 affected the venom response. This was further supported by the failure of venom to degranulate in vitro peritoneal mast cells. In conclusion, only vanilloid receptors and P 2 prejunctional purinoceptors had an inhibitory effect on the neurogenic plasma extravasation evoked by P. nigriventer venom in rat dorsal skin.

PACAP-induced plasma extravasation in rat skin

The effects of pituitary adenylate cyclase activating peptide (PACAP) 38, PACAP 27 and vasoactive intestinal peptide (VIP) on plasma extravasation were investigated in vivo in rat skin. PACAP 38, PACAP 27 and VIP, caused concentration-dependent extravasation in rat skin. The order of potency was PACAP 38>PACAP 27=VIP, whereas the order of maximal induced extravasation was PACAP 38=PACAP 27>VIP, suggesting that PACAP 38 might be the most powerful inducer of plasma extravasation of the three tested members of the secretin-glucagon-VIP family. Substance P (SP) was about 5 times more potent than PACAP 38 and 15 times more potent than PACAP 27. These data indicate that PACAP 38 induced plasma extravasation in concentrations roughly equimolar to SP. Pyrilamine (H 1 receptor antagonist) reduced the PACAP 38-induced plasma extravasation more than 50%; cimetidine (H 2 receptor antagonist) was without effect. To investigate whether a cAMP-mediated process is involved in the induction of plasma extravasation, the synthetic adenosine 3′,5′-cyclic monophosphate (cAMP), dibutyryl adenosine cyclic monophosphate (DBcAMP) and the cAMP-inducing drug, salbutamol, were each injected in the skin; neither of these drugs caused extravasation. We conclude that PACAP 38 and PACAP 27 cause potent plasma extravasation which, at least in part, involves histamine release.

Effect of the inducible nitric oxide synthase inhibitors aminoguanidine and L-N6-(1-iminoethyl)lysine on zymosan-induced plasma extravasation in rat skin.

The effect of nitric oxide synthase (NOS) inhibitors on plasma extravasation in a rat model of zymosan-induced inflammation has been investigated. Plasma extravasation was determined in response to intradermal test agents over 0 to 45 min or 0 to 4 h by the accumulation of i.v. injected 125I-labeled human serum albumin. Zymosan (1-100 microg/site) produced a dose- and time-dependent plasma extravasation. N(G)-nitro-L-arginine methyl ester (30-300 nmol/site), but not aminoguanidine (AG; 10-300 nmol/site) or L-N6-(1-iminoethyl)lysine (L-NIL; 10-300 nmol/site), significantly (p < 0.01) inhibited zymosan-induced (10 microg/site) plasma extravasation over 0 to 45 min. However, both AG and L-NIL produced significant (p < 0.05) inhibition over 0 to 4 h. The inhibition produced by AG was reversed by i.v. L-arginine or by coinjection of the vasodilator, calcitonin gene-related peptide. Zymosan (10-100 microg/site) induced an increase in dermal blood flow (laser-Doppler flowmetry) and this was inhibited by AG. Neutrophils were depleted selectively with antiserum, but this did not affect plasma extravasation except at the highest dose of zymosan (100 microg/site). Furthermore, zymosan-induced edema was not modified at either time point by pretreatment with the cyclooxygenase inhibitor indomethacin (30 micromol/kg, s.c., -30 min). In conclusion, in this model of dermal inflammation, it is suggested that inducible NOS inhibitors selectively remove an inducible NOS component that, at least in part, acts to increase microvascular blood flow and thus the edema formation observed during 0 to 4 h. There is no evidence of a contributory role for neutrophils or cyclooxygenase products in this model.

Investigation of 6-hydroxydopamine-induced plasma extravasation in rat skin

Perfusion of 6-hydroxydopamine into the rat knee and trachea induces plasma extravasation, possibly by tissue-specific mechanisms involving sympathetic and sensory nerves respectively, and we aimed to identify the mediators which contribute to this response in skin. 6-Hydroxydopamine (both hydrobromide and hydrochloride salts), dose dependently increased plasma extravasation into rat dorsal skin, however, when compared to bradykinin or the tachykinin NK 1 receptor agonist GR73632, high concentrations of 6-hydroxydopamine (1–10 μmol/site) were required. The response to 6-hydroxydopamine was not inhibited in chemically sympathectomised rats (6-hydroxydopamine, 300 mg/kg i.p. over 7 days) but was significantly reduced by co-administration with the histamine (H 1) and the 5-HT receptor antagonists mepyramine and methysergide and in skin sites pre-injected with compound 48 80 (4 μg, −18 h) to degranulate dermal mast cells. The response was not inhibited by co-injection of the tachykinin NK 1 receptor antagonist SR140333 or by the cyclo-oxygenase inhibitor indomethacin (5 mg kg −1 i.p., −30 min) except at the lowest dose of 6-hydroxydopamine (1 μmol/site). We conclude that 6-hydroxydopamine is not a potent or selective mediator of increased vascular permeability in rat skin but, at high concentrations, may induce oedema formation via release of vasoactive amines from mast cells, augmented by generation of prostaglandins.

Peripheral administration of nerve growth factor in the adult rat produces a thermal hyperalgesia that requires the presence of sympathetic post-ganglionic neurones

Previous evidence suggests that, in adult animals, nerve growth factor (NGF) can induce hyperalgesia, and may be an endogenous mediator in some persistent pain states. Here we have studied the effects of single intradermal injections of 50–500 ng of human recombinant NGF into the plantar skin of adult rat hindpaws. We found that doses of 250 ng and more produced a prolonged and stable thermal hyperalgesia to radiant heat. NGF did not produce overt pain behaviour as judged by the absence of paw licking or guarding of the injected paw. In animals subjected to surgical or chemical sympathectomy, by repeated systemic guanethidine treatments, the hyperalgesic effects of NGF were markedly reduced. We also found that NGF produced plasma extravasation in rat skin, using the EBAN's blue method, with a dose dependency similar to that determined for hyperalgesia. Together, these findings suggest that NGF can lead to a rapid activation and sensitization of cutaneous nociceptors.However, these actions appear at least partly indirect, requiring the presence of normal sympathetic post-ganglionic terminals.

μ- and κ-opioid receptor agonists produce peripheral inhibition of neurogenic plasma extravasation in rat skin

Extravasation elicited in rat skin by antidromic electrical stimulation of the saphenous nerve was dose dependently inhibited by the intravenous (i.v.) application of the μ-opioid receptor agonists, morphine and [D-Ala 2,Me-Phe 4,Gly-ol 5]enkephalin (DAGO), and the κ-opioid receptor agonists (−)-U 50488H, (−)-ICI 197067 and ICI 204448. This inhibition was antagonised by naloxone, and the lack of action of (+)-U 50488H (5 mg/kg) indicated that the κ effect was stereoselective. The δ-opioid receptor agonist, [D-Pen 2, D-Pen 5]enkephalin (DPDPE), and the σ-receptor agonist, (+)-SKF 10047, had no effect on neurogenic extravasation at a dose of 5 mg/kg. Opiate-induced changes in cutaneous blood flow were not important for opiate inhibition since extravasation produced by exogenous substance P (the putative neurotransmitter) was not influenced by the opiates. An indirect opiate action via the adrenal glands was excluded since the effectiveness of DAGO, (−) - ICI 197067 and ICI 204448 was unchanged after adrenalectomy. Finally, the cutaneous locus of the opiate effect was shown by blocking the activity of systematically applied DAGO and ICI 204448 with naloxone injected into paw. These results indicate that specific μ-opioid and κ-opioid, but not δ-opioid and σ receptor agonists, inhibit neurogenic plasma extravasation in rat skin, probably via opioid receptors on peripheral terminals of sensory C-fibres.

Inhibitory Effect of Tranilast on Substance P-Induced Plasma Extravasation in Rat Skin

The effect of tranilast, an inhibitor for IgE-mediated mediator release from mast cells, on plasma extravasation induced by the intradermal injection of substance P in rats was examined. Tranilast (100 mg/kg, intraperitoneally) decreased plasma extravasation induced by substance P (10(-7)-10(-5) M). Tranilast decreased plasma extravasation induced by the amino-terminal peptide substance P1-9 (10(-6)-10(-4) M), which is active for rat mast cells, but not by the carboxy-terminal peptide substance P6-11 (10(-6)-10(-4) M), which is inactive for the mast cells. Therefore, tranilast prevents substance P-induced plasma extravasation most likely by inhibiting mast cell degranulation.

Sequence of events in substance P-mediated plasma extravasation in rat skin

Using a blister model of inflammation in the rat hind footpad, we have studied the temporal and quantitative contribution of mast cell mediators and prostaglandins to substance P-induced plasma extravasation. In addition substance P-related peptides (neurokinin A, SP 5–11 and SP 1–7) were tested for their ability to induce a plasma extravasation response and the extent of histamine involvement to the response was determined. The present results show that the plasma extravasation response to substance P consists of an early substance P-mediated response that is independent of other mediators and a late response that involves interaction between substance P, mast cell mediators and prostaglandins. An early histamine-independent response was also mediated by neurokinin A, a tachykinin that shares a common C-terminal with substance P and by a C-terminally directed analogue of substance P, namely SP 5–11. On the other hand, a late histamine-dependent response was mediated by the N-terminally directed analogue, SP 1–7. The present data are suggestive of a possible sequence of events that might occur during an inflammatory response to substance P and might involve independent actions of its C- and N-terminal.

Small diameter myelinated afferents produce vasodilatation but not plasma extravasation in rat skin.

1. Antidromic stimulation of the rat saphenous nerve at intensities sufficient to excite small myelinated (A delta) fibres but not unmyelinated (C) fibres produced evidence of a transient increase in skin blood flow in the saphenous nerve territory. The magnitude and time course of the vasodilatation depended on the number and frequency of stimuli delivered to the nerve. 2. There was no evidence of an accompanying plasma extravasation. 3. The results suggest that A delta afferent fibres are involved in axon reflex/axon response reactions as well as unmyelinated (C) afferent fibres.

NK‐1 receptor mediation of neurogenic plasma extravasation in rat skin

1. Plasma extravasation was induced by electrical nerve stimulation and by perfusion of tachykinins over a vacuum-induced blister base on rat footpad. 2. Stimulation of the sciatic nerve (18 V, 15 Hz, 0.5 ms) for 20 min produced a significant increase in the protein content of the perfusate. The response in capsaicin pretreated rats was only 4% of the control response. This indicates that the electrically-induced plasma extravasation response was mediated by capsaicin-sensitive sensory fibres. 3. Exogenous perfusion of the mammalian tachykinins substance P, neurokinin A and neurokinin B and the non-mammalian tachykinins physalaemin, kassinin and eledoisin was used to determine the tachykinin receptor type mediating the plasma extravasation response. Dose-response curves of the tachykinins (10(-9) M-10(-4) M) gave a rank order of potency of substance P = physalaemin greater than eledoisin greater than or equal to kassinin greater than neurokinin B = neurokinin A. 4. In addition, specific agonists of neurokinin receptors were perfused. Perfusion of [Glp6, D-Pro9] SP6-11 and [Glp6, L-Pro9]SP6-11 demonstrated that the L-Pro isomer was much more potent than the D-Pro isomer. 5. The rank order of potency and the greater potency of [Glp6, L-Pro9]SP6-11 over its D-isomer indicate an NK-1 neurokinin receptor mediates plasma extravasation in rat footpad skin.

Plasma Extravasation by Chemical Mediators in Rat Skin and Trachea: A Role of Neurogenic Agents on Tracheal Edema Formation

The plasma extravasation inducing activities of several chemical mediators (allergic agents: histamine, leukotriene C4 (LTC4) and platelet activating factor (PAF); neurogenic agents: substance P, capsaicin and carbachol) have been investigated and characterized in rat skin and trachea. Substance P, histamine, LTC4 and PAF induced dose-dependent plasma extravasation in rat skin. The activities of these mediators in inducing tracheal plasma extravasation were very different from those in the skin reactions. When these mediators were injected intravenously, substance P induced severe plasma extravasation, and the activities of histamine and PAF were weaker than that of substance P. When injected intratracheally, only substance P and capsaicin induced tracheal plasma extravasation, while none of the allergic mediators tested caused any plasma extravasation in the trachea. Carbachol did not induce any plasma extravasation in either skin or trachea. These results indicate that the stimulation of afferent substance P-containing nerve fibers has a more important role in the induction of tracheal plasma extravasation than that of allergic chemical mediators.

Plasma extravasation by chemical mediators in rat skin and trachea: A role of neurogenic agents on tracheal edema formation.

The plasma extravasation inducing activities of several chemical mediators (allergic agents: histamine, leukotriene C4 (LTC4) and platelet activating factor (PAF); neurogenic agents: substance P, capsaicin and carbachol) have been investigated and characterized in rat skin and trachea. Substance P, histamine, LTC4 and PAF induced dose-dependent plasma extravasation in rat skin. The activities of these mediators in inducing tracheal plasma extravasation were very different from those in the skin reactions. When these mediators were injected intravenously, substance P induced severe plasma extravasation, and the activities of histamine and PAF were weaker than that of substance P. When injected intratracheally, only substance P and capsaicin induced tracheal plasma extravasation, while none of the allergic mediators tested caused any plasma extravasation in the trachea. Carbachol did not induce any plasma extravasation in either skin or trachea. These results indicate that the stimulation of afferent substance P-containing nerve fibers has a more important role in the induction of tracheal plasma extravasation than that of allergic chemical mediators.

Nerve growth factor induces plasma extravasation in rat skin

The intradermal application of both mouse and bovine nerve growth factor induced dose-dependently increased vascular permeability as indicated by Evans blue extravasation. Plasma extravasation by nerve growth factor was markedly reduced by capsaicin pretreatment or a combination of H 1- and H 2-histamine antagonists. The finding that biologically inactive nerve growth factor failed to elicit protein leakage indicates that plasma extravasation by nerve growth factor is a characteristic of the biologically active molecule.