Effect of salicylate poisoning on insulin secretion. Studies on its mechanism of action

Abstract

Sodium salicylate poisoning increased glucose-induced insulin secretion by slices of rat pancreas. The alpha adrenergic blocker phentolamine, but not salicylate poisoning, overcame the inhibitory effect of epinephrine on insulin secretion. Theophylline (5, 10 and 15 mM) significantly increased the insulin secretion induced by 11 mM glucose. The highest insulin response was obtained when theophylline was used at a 10 mM concentration. However, when pancreas slices from salicylate poisoned rats were used, a 5 mM concentration was sufficient to achieve maximal insulin response. Salicylate poisoning diminished the free tubulin pool, an action that was impaired by imidazole; however, imidazole did not modify the effect of the ionophore A23187. The results suggest that: a) sodium salicylate poisoning increases B-cell response to glucose; b) changes in alpha adrenergic activity are not related to the mechanism of action of salicylate; c) an increment in the cAMP concentration may mediate the stimulatory effect of salicylate poisoning on insulin secretion; d) the effect of salicylate on the microtubular system is indirect and probably mediated through an increment in pancreatic cAMP.

First approach to pod dehiscence in faba bean: genetic and histological analyses

“…This observation is similar to that described in Brassica species, where indehiscent species show a more lignified endocarp than dehiscent ones 54 . By contrast, our findings are opposed to those reported from histological studies in common bean and soybean, where pod valves of the wild dehiscent lines showed a strong lignified wall fiber layer contrasting with a complete absence of lignin deposition in the indehiscent lines 21 , 26 , 34 , 55 , 56 , 58 .…”

“…Collectively, these studies suggest that pathways and loci controlling pod dehiscence are broadly conserved across taxa, pointing towards homologous mechanisms underlying dehiscence. However, while a convergent phenotypic evolution was proposed across cereals, which might also have occurred at orthologous loci in closely related legume species, such evidence has not been obtained so far across more distant legume crops 34 . Comparative mapping between P. vulgaris and G. max suggested that the convergent evolution of the indehiscent phenotypes derived from mutations at different genes involved in pod cell wall biosynthesis and lignin deposition 44 , which suggested a more complex pattern in the genetic control of this trait in legumes.…”

“…Pod dehiscence causes important agronomic losses and regarded as a key trait in crop domestication 22 , 34 . In legumes such as chickpea, soybean or pea, clear differences in dehiscence between wild (dehiscent) and cultivated (indehiscent) accessions were reported 22 , 35 , 36 , showing the results of many years of domestication.…”

“…Important progress has been made in the characterization of the genetic basis of dehiscence in a number of model species and crops such as wheat, rice, soybean, beans, lentil, pea among others (reviewed by 5 , 14 , 26 , 34 , 38 ). Collectively, these studies suggest that pathways and loci controlling pod dehiscence are broadly conserved across taxa, pointing towards homologous mechanisms underlying dehiscence.…”

Insulin secretion stimulated by allogeneic lymphocytes in an inbred strain of mice.

“…Alloantigen injection, in turn, modified not only the amount but also the pattern of 5.5 mM glucose-induced hormone secretion, substituting a monophasic by a biphasic profile. Incidentally, the change in the insulin secretion pattern caused by the injection of allogeneic lymphocytes, where 5.5 mM glucose is used as stimulus, was similar to that elicited by glibenclamide, sodium salicylate, or theophylline, all substances with previously reported stimulatory effects on cyclic AMP pancreatic levels (22)(23)(24). Although any comment or tentative explanation would be, at'present, only speculative, these results could suggest that the increase in beta cell sensitivity to glucose caused by alloantigen injection might be mediated, at least in part, by an effect on cyclic AMP levels.…”