ucn-1028-c and Body-Weight

Oxaliplatin is a platinum-based chemotherapy drug characterized by the development of a painful peripheral neuropathy which is reproduced in rodent animal models with features observed in humans. Our focus was to explore the alterations of intracellular second messengers at supraspinal level in oxaliplatin-induced mechanical hyperalgesia. In our experiments, chronic administration of oxaliplatin to rats induced mechanical hyperalgesia which lasted for many days. When the hyperalgesic rats were submitted to paw pressure test in the presence of selective PKC inhibitor Calphostin C supraspinally administered, hyperalgesic effect could be reversed showing that PKC activity in supraspinal brain regions is needed. Concurrently, oxaliplatin chronic treatment induced a specific upregulation of gamma isoforms of PKC and increased phosphorylation of gamma/epsilon PKC isoforms within thalamus and PAG. Phosphorylation was reversed when PKC activity was inhibited by Calphostin C. Distinct PKC-activated MAPK pathways, including p38MAPK, ERK1/2 and JNK, were investigated in chronic oxaliplatin rat. A dramatic phosphorylation increase, Calphostin C sensitive, could be observed in thalamus and PAG for p38MAPK. These data show that, in oxaliplatin-induced neuropathy, enhanced mechanical nociception is strictly correlated with increased phosphorylation of specific intracellular mediators in PAG and thalamus brain regions pointing to a role of these supraspinal centers in oxaliplatin-induced neuropathic pain mechanism.

Topics: Animals; Antineoplastic Agents; Blotting, Western; Body Weight; Enzyme Inhibitors; Hyperalgesia; Injections, Intraventricular; Male; Naphthalenes; Organoplatinum Compounds; Oxaliplatin; Pain Measurement; Peripheral Nervous System Diseases; Phosphorylation; Physical Stimulation; Postural Balance; Pressure; Protein Kinase C; Rats; Rats, Sprague-Dawley; Second Messenger Systems; Signal Transduction

The vascular effects of glucose-intolerance were investigated using the neonatal streptozotocin-treated (nSTZ) rat model. Glucose-intolerance was initiated by administration of STZ (90 mg/kg, IP) into 2-day-old male rats. Aortic reactivity was assessed in vitro at 3 and 6 months of age. Both the 3- and 6-month-old nSTZ rats displayed higher blood glucose levels in response to a glucose challenge. At 3 months of age, aortic responsiveness to both norepinephrine and acetylcholine was not altered. However, at 6 months of age, the responses of endothelium-denuded aortas from nSTZ rats to norepinephrine and serotonin were enhanced compared to controls. Endothelium-mediated relaxation of aortas from these animals to acetylcholine was also augmented, and this effect was linked to NO release. Although norepinephrine did not elicit enhancement of aortic contraction in calcium-free medium in 6-month-old nSTZ rats, the responses to both maximum and submaximum concentrations of the agonist after readdition of calcium were greater in these tissues than in control preparations. Pretreatment of aortas with calphostin C eliminated the difference in NE-induced contraction between the control and experimental groups. Although the concentration-response curves for phorbol 12,13-dibutyrate were not different between the 2 groups, the responses of the aortas from 6-month-old nSTZ rats to a submaximum concentration of the phorbol ester were enhanced relative to controls, and this enhancement was normalized with calphostin C. Overall, the data suggest that glucose-intolerance of sufficient duration causes increases in vascular reactivity to agonists. While these findings warrant further investigations, such vascular alterations during the prediabetes stage of glucose intolerance can be a predisposing factor for the eventual development of cardiovascular complications.

Topics: Acetylcholine; Animals; Animals, Newborn; Aorta; Blood Glucose; Body Weight; Calcium; Diabetes Mellitus, Experimental; Dose-Response Relationship, Drug; Egtazic Acid; Glucose Intolerance; Glucose Tolerance Test; In Vitro Techniques; Male; Naphthalenes; NG-Nitroarginine Methyl Ester; Nitroprusside; Norepinephrine; Phorbol 12,13-Dibutyrate; Protein Kinase C; Protein Kinase Inhibitors; Rats; Rats, Inbred WKY; Serotonin; Vasoconstriction; Vasodilation

The main objectives of this study were to investigate the effects of deoxycorticosterone acetate (DOCA)-induced hypertension on the aortic and mesenteric vascular responses to vasodilator and vasoconstrictor agents and also to elucidate whether protein kinase C (PKC) was involved in these responses, by using chelerythrine and calphostin C, the inhibitors of protein kinase C. Hypertension was induced in male Sprague-Dawley rats (200-250 g) by DOCA-salt injection [20 mg/kg, twice weekly for 5 weeks, subcutaneously (s.c.)] and NaCl (1%) was added to their drinking water. Control rats received a saline injection (0.5 ml/kg, twice weekly for 5 weeks, s.c.), then the animals were anaesthetised [thiopental, 30 mg/kg, intraperitoneally (i.p.)] and the arterial blood pressure was measured. Mean arterial blood pressure in control and hypertensive rats were 98+/-7.5 and 163+/-3.5 mmHg, respectively (P<0.0001). In the in vitro studies, rings of descending aorta and mesenteric beds were precontracted with phenylephrine and then concentration-response curves to acetylcholine and sodium nitroprusside were constructed. In the tissue removed from hypertensive rats, the responses to acetylcholine, but not to sodium nitroprusside, were significantly reduced. However, addition of chelerythrine (10 microM) or calphostin C (100 nM) to the organ bath significantly restored these impaired responses. Our data suggest that protein kinase C plays a crucial role in the endothelial dysfunction induced by hypertension.

Topics: Acetylcholine; Alkaloids; Anesthesia; Animals; Aorta, Thoracic; Benzophenanthridines; Blood Pressure; Body Weight; Desoxycorticosterone; Dose-Response Relationship, Drug; Endothelium, Vascular; Enzyme Inhibitors; Heart; Heart Rate; Hypertension; In Vitro Techniques; Male; Naphthalenes; Nitroprusside; Organ Size; Phenanthridines; Phenylephrine; Protein Kinase C; Rats; Rats, Sprague-Dawley; Splanchnic Circulation; Vasodilator Agents

A fructose-enriched diet induces an increase in blood pressure associated with metabolic alterations in rats. Our hypothesis was that an increase in protein kinase C (PKC) activation, reported in the acute period of fructose overload, and an impaired vessel's response to vasoactive substances contribute to maintain elevated blood pressure levels in the chronic period. The aims of this study were to investigate in this animal model of hypertension: (1) if the increase in PKC activation was also found in the chronic stage; (2) the involvement of nitric oxide and insulin in the vessel's response; and plasma atrial natriuretic factor and nitrites/nitrates (nitric oxide metabolites) behavior. We evaluated the effects of: PKC-stimulator 12,13-phorbol dibutyrate, phenylephrine, insulin, nitric oxide synthase-inhibitor NG-nitro-L-arginine methyl esther (L-NAME) and PKC-inhibitor Calphostin C on aortic rings responses of Sprague-Dawley rats: fructose-fed and control. The fructose-fed group showed higher contractility to 12,13-phorbol dibutyrate than the control group in aortic rings pre-incubated with insulin, and this difference disappeared with L-NAME. The response to phenylephrine in rings pre-incubated with Calphostin C was decreased in the fructose-fed group and increased with Calphostin C plus L-NAME. Fructose-fed rats showed higher levels of plasma atrial natriuretic factor and nitrites/nitrates than controls. In conclusion, chronic fructose feeding seems to develop an impaired response to insulin, dependent on nitric oxide, suggesting a PKC alteration. Vasorelaxant agents, such as atrial natriuretic factor and nitric oxide, would behave as compensatory mechanisms in response to high blood pressure.

Topics: Animals; Atrial Natriuretic Factor; Blood Pressure; Body Weight; Enzyme Activators; Enzyme Inhibitors; Fructose; Hypertension; Hypoglycemic Agents; Insulin; Insulin Resistance; Male; Muscle Contraction; Muscle, Smooth, Vascular; Naphthalenes; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Phorbol 12,13-Dibutyrate; Protein Kinase C; Rats; Rats, Sprague-Dawley

Experimental diabetes promotes changes in biochemical activities of peripheral nervous tissue. Glutathione peroxidase activity decreases in sciatic nerve of diabetic mice very early after onset of experimental diabetes. Effective glycemic control with insulin restores the early lost glutathione peroxidase activity in peripheral nerve of diabetic mice to control values. Data are also presented demonstrating that glutathione peroxidase activity in diabetic mouse peripheral nerve is not modified by the constant delivery of calphostin C, a protein kinase C inhibitor, therefore this decrease seems to be independent on a protein kinase C mediated mechanism. Thus, the early glutathione peroxidase activity decrease in peripheral nerve of diabetic mice is closely related to hyperglycemia, and a tight glycemic control is rather effective in restoring the control levels of this enzymatic activity. The results herein do not rule out the benefits of antioxidant adjuvant therapies in diabetes to help recover the overall decrease in antioxidant defense in peripheral nerve elicited by the decrease of glutathione peroxidase activity.

Topics: Animals; Blood Glucose; Body Weight; Cytosol; Diabetes Mellitus, Experimental; Enzyme Inhibitors; Glutathione Peroxidase; Male; Mice; Naphthalenes; Protein Kinase C; Sciatic Nerve; Time Factors

We investigated protein kinase C participation in the contractile response to 5-hydroxytryptamine (5-HT), and in the interaction between 5-HT and endothelin-1, in aortas from control and diabetic rats. Diabetic rats display attenuated reactivity to 5-HT (i.e., approximately 47% of control maximum). The protein kinase C inhibitor calphostin C (1 microM) significantly reduced responses to 5-HT only in aortas from control rats. In diabetic rats, maximum responses to 5-HT, in the presence of endothelin-1 (3 nM), were not significantly different to controls. The additional presence of calphostin C significantly reduced responses only in aortas from diabetic rats. These results may indicate an abnormality in the protein kinase C second messenger system during diabetes.

Topics: Animals; Aorta, Thoracic; Blood Glucose; Body Weight; Diabetes Mellitus, Experimental; Endothelin-1; Enzyme Activation; Enzyme Inhibitors; In Vitro Techniques; Male; Muscle Contraction; Muscle, Smooth, Vascular; Naphthalenes; Protein Kinase C; Rats; Rats, Wistar; Serotonin