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Researchers in Brazil Publish New Research Findings on Physiology and Molecular Biology

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— 2 min read

Scientists from the State University of Campinas in Brazil have published several new research findings in the fields of physiology and molecular biology. These studies shed light on the mechanisms of insulin signaling, the effects of propranolol on arterial smooth muscle, and the regulation of blood pressure in sino-aortic-denervated rats.

Key Takeaways:

  • Study 1: Phosphoinositide-specific inositol polyphosphate 5-phosphatase IV (5ptase IV) plays a crucial role in regulating food intake and body weight by inhibiting inositol trisphosphate accumulation in the hypothalamus. Researchers used a phosphorothioate-modified antisense oligonucleotide to reduce the expression of 5ptase IV in rats, resulting in reduced food intake and body weight loss.
  • Study 2: dl-Propranolol, a non-selective beta-blocker, relaxes arterial smooth muscle by activating the NO-cGMP pathway and blocking calcium influx, independent of beta-adrenoceptor blockade. The study found that propranolol increased cGMP levels in endothelium-intact preparations and caused a rightward shift in the concentration-response curves to calcium chloride in tissues with either intact or denuded endothelium.
  • Study 3: In sino-aortic-denervated rats, an elevation in blood pressure appears to offset increased renal sympathetic discharge with no change in plasma renin activity. Researchers found that the increase in blood pressure associated with sino-aortic baroreceptor denervation was prevented by continuous infusion of sodium nitroprusside, which resulted in a significant increase in plasma renin activity.

Statistics:

  • Study 1: The treatment of rats with a phosphorothioate-modified antisense oligonucleotide specific for 5ptase IV resulted in an approximately 20% reduction in insulin-induced tyrosine phosphorylation of 5ptase IV and an increase in basal accumulation of phosphorylated inositols in the hypothalamus.
  • Study 2: The relaxation responses induced by dl-propranolol were significantly reduced in aortic and mesenteric rings precontracted with phorbol-12,13-dibutyrate (1 mmol/L).
  • Study 3: The increase in blood pressure associated with sino-aortic baroreceptor denervation was approximately 36 mmHg (152±4 vs. 116±3 mmHg).
  • Study 3: Plasma renin activity remained unchanged in sino-aortic-denervated rats (1.67±0.35 vs. 1.05±0.17 ng angiotensin I/mL per h), but increased significantly when hypertension was prevented (5.86±0.77 ng AngI/mL per h; n=5; p<0.05).

Sources:

  • "Phosphoinositide-specific inositol polyphosphate 5-phosphatase IV inhibits inositide trisphosphate accumulation in hypothalamus and regulates food intake and body weight." Endocrinology, 2006;147(11):5385-99. Published by Bertelli et al.
  • "Vasorelaxing effects of propranolol in rat aorta and mesenteric artery: A role for nitric oxide and calcium entry blockade." Clinical and Experimental Pharmacology and Physiology, 2006;33(5-6):448-455. Published by Priviero et al.
  • "Dissociation of blood pressure and sympathetic activation of renin release in sinoaortic-denervated rats." Clinical and Experimental Pharmacology and Physiology, 2006;33(5-6):471-476. Published by Krieger et al.

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