nitroarginine and Weight-Loss

Administration of cobaltic protoporphyrin IX (CoPP) into the third ventricle of the brain by intracerebroventricular injection in rodents is known to result in transient hypophagia and remarkably prolonged weight loss. The mechanism of action of CoPP in eliciting these effects is unknown. It is known that nitric oxide plays a role in food intake and that the hyperphagia that results from a wide variety of genetic, physiological, and pharmacological stimuli can be blocked by the administration of inhibitors of the enzyme nitric oxide synthase (NOS). We demonstrate that intracerebroventricular administration of compounds that alter nitrergic tone can also change food ingestion and weight gain patterns in normophagic rats. We also demonstrate that CoPP decreases NOS activity but that it paradoxically increases neuronal NOS transcript expression and increases neuronal NOS protein content on Western blotting.

Topics: Animals; Eating; Enzyme Inhibitors; Hyperphagia; Hypothalamus; Immunohistochemistry; Male; Neurons; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Nitroarginine; Protoporphyrins; Rats; Rats, Sprague-Dawley; RNA, Messenger; Weight Loss

Pentoxifylline has several actions that improve blood rheology and tissue perfusion and may therefore potentially be applicable to diabetic neuropathy. The aims of this study were to ascertain whether 2 weeks of treatment with pentoxifylline could correct nerve conduction velocity and blood flow deficits in 6-week streptozotocin-diabetic rats and to examine whether the effects were blocked by co-treatment with the cyclooxygenase inhibitor, flurbiprofen, or the nitric oxide synthase inhibitor, NG-nitro-L-arginine. Diabetic deficits in sciatic motor and saphenous sensory nerve conduction velocity were 56.5% and 69.8% corrected, respectively, with pentoxifylline treatment. Sciatic endoneurial blood flow was approximately halved by diabetes and this deficit was 50.4% corrected by pentoxifylline. Flurbiprofen co-treatment markedly attenuated these actions of pentoxifylline on nerve conduction and blood flow whereas NG-nitro-L-arginine was without effect. Thus, pentoxifylline treatment confers neurovascular benefits in experimental diabetic neuropathy, which are linked at least in part to cyclooxygenase-mediated metabolism.

Topics: Animals; Blood Glucose; Cyclooxygenase Inhibitors; Diabetes Mellitus, Experimental; Flurbiprofen; Male; Neural Conduction; Nitric Oxide Synthase; Nitroarginine; Pentoxifylline; Peripheral Nerves; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Sciatic Nerve; Weight Loss