Regulatory peptides
-
Regulatory peptides · Apr 2005
Cocaine- and amphetamine-regulated transcript peptide potentiates spinal glutamatergic sympathoexcitation in anesthetized rats.
Cocaine- and amphetamine-regulated transcript (CART) is widely expressed in the rat central nervous system, notably in areas involved in control of autonomic and neuroendocrine functions. The aim of this study was to evaluate the effects of CART peptide fragment 55-102, referred to herein as CARTp, by intrathecal injection on blood pressure (BP) and heart rate (HR) before and after intrathecal glutamate in urethane-anesthetized male Sprague-Dawley rats. CARTp (0.1-10 nmol) administered intrathecally caused no or a small, statistically insignificant increase of blood pressure and heart rate, except at the concentration of 10 nmol, which caused a significant increase of blood pressure and heart rate. ⋯ The effect of CARTp was long-lasting, as it enhanced glutamatergic responses up to 90 min after administration. Prior injection of CARTp antiserum (1:500) but not normal rabbit serum nullified the potentiating effect of CARTp on glutamatergic responses. The result suggests that CARTp, whose immunoreactivity is detectable in sympathetic preganglionic neurons as well as in fibers projecting into the intermediolateral cell column, augments spinal sympathetic outflow elicited by glutamate at lower concentrations and may directly excite neurons in the intermediolateral cell column at higher concentrations.
-
Regulatory peptides · Apr 2005
Serotonin-induced enhancement of vasopressin and oxytocin secretion in rat neurohypophyseal tissue culture.
The effects of serotonin (5-hydroxytryptamine; 5-HT) on vasopressin (VP) and oxytocin (OT) secretion were studied in 13-14-day cultures of isolated rat neurohypophyseal (NH) tissue. The VP and OT contents of the supernatant were determined by radioimmunoassay after a 1 or 2 h incubation. Significantly increased levels of VP and OT production were detected in the tissue culture media following 5-HT administration, depending on the 5-HT dose. ⋯ The application of WAY-100635, ketanserin or metergoline, after 5-HT administration proved ineffective. The results indicate that NH hormone release is influenced directly by the serotonergic system. The serotonergic control of VP and OT secretion from the NH tissue in rats can occur at the level of the posterior pituitary.
-
Regulatory peptides · Apr 2005
Absence of diabetic hyperalgesia in bradykinin B1 receptor-knockout mice.
Experimental evidence has shown that the inducible bradykinin (BK) B1 receptor (BKB1-R) subtype is involved in the development of hyperalgesia associated with type 1 diabetes. Selective BKB1-R antagonists inhibited, whereas selective agonists increased the hyperalgesic activity in diabetic mice in thermal nociceptive tests. Here we evaluate the development of diabetic hyperalgesia in a BKB1-R-knockout (KO) genotype compared to wild-type (WT) mice. ⋯ The hyperalgesia observed in wild type mice was totally absent in the BKB1-R-KO mice. Furthermore, the selective BKB1-R agonist, desArg9BK, significantly increased the hyperalgesic activity in diabetic WT mice but had no effect on nociceptive responses in diabetic BKB1-R-KO mice. Taken together, the results confirm the crucial role of the BKB1-R, upregulated alongside inflammatory diabetes, in the development of diabetes-induced hyperalgesia.