[The activity of receptor guanylyl cyclases in tissues of rats with neonatal streptozotocin diabetus mellitus and the influence of intranasal administration of insulin and serotonin].

Functional activity of hormanal signaling systems and their sensitivity to regulatory actions of hormones in diabetes mellitus (DM) and its complications are altered. The activity of receptor forms of guanylyl cyclases (rGC) sensitive to natriuretic peptides, ANP and CNP, in tissues of female rats with 240-days neonatal streptozotocin DM and the influence of intranasal administration of insulin and serotonin (6 weeks, daily dose is 0.48 IU of insulin or 20 microg of serotonin to rat) on this activity were studied. In diabetic animals, the increase of the basal activity of rGC in the myocardium and its decrease in the uterus and ovaries were found, whereas the brain showed no differences from control animals. The treatment of diabetic rats with insulin led to a decrease in the basal activity of rGC in the myocardium and to its restoration to normal level in the ovaries. Serotonin treatment induced a less pronounced compared with insulin decrease in the basal activity of the enzyme in the myocardium and also a slight increase the activity in the brain. In the myocardium of diabetic rats, the weakening of GC stimulating effect of ANP and, on the contrary, the strengthening of CNP effect were observed. In the ovaries, GC stimulating effect of CNP and, to a lesser degree, the corresponding effect of ANP were decreased. In the uterus and the brain, the sensitivity of rGC to hormones was practically not changed. The administration of insulin to diabetic rats induced an increase in GC effect of ANP in the myocardium to its values in control animals and a decrease in CNP effect as well as in partially restored GC effect of CNP in the ovaries. Serotonin treatment led to some increase in the effects of natriuretic peptides in the brain of both control and diabetic animals. Summing up, in neonatal model of type 2 DM in the myocardium and the tissues of reproductive system of rats the functioning of natriuretic peptide-sensitive rGC is altered in the myocardium and the tissues of reproductive system of model rats with neonatal type 2 DM. Treatment of animals with insulin substantially restores rGC activity while intranasal administration of serotonin has little effect.