[The modern concept of the regulatory role of peptides of the glyproline family in the correction of hemostasis system function during development of diabetes mellitus]

The experimental data on the therapeutic and prophylactic antidiabetogenic effect of di-, tri-, and tetrapeptides of the glyproline family with the additional inclusion of arginine or leucine at different positions are presented. The results are obtained using two animal models: with insulin-dependent diabetes mellitus (type 1), and persistent hyperglycemia similar to development of non-insulin-dependent diabetes mellitus (type 2) in humans. It is shown that repeated intranasal administration of Pro-Gly, Pro-Gly-Pro, Pro-Gly-Pro-Arg, Pro-Gly-Arg, Arg-Pro-Gly, Arg-Pro-Gly-Pro, Gly-Pro-Arg, Pro-Arg-Gly, Pro-Gly-Pro-Leu, Leu-Pro-Gly-Pro peptides to rats with hyperglycemia of different etiology led to the combined normoglycemic and anticoagulant effects in the blood plasma. The concept of the regulatory role of short proline-containing peptides, involving the universality of their action in the organism and directed towards the regulation of both hemostasis and insular systems in a variety of their physiological and clinical manifestations, was formulated.

Arginine-containing tripeptide Pro-Arg-Gly is involved in the regulation of the function of anticoagulation and insular systems under persistent hyperglycemia

Intranasal administration of regulatory peptide PRG to rats against the background of persistent hyperglycemia improves blood antiplatelet and anticoagulant-fibrinolytic potential and normalizes blood sugar in comparison with the corresponding parameters in control animals that did not receive the peptide. The fibrinolytic and antiplatelet activities of blood plasma remained elevated 6 days after peptide withdrawal against the background of unchanged glucose administration.

Semax attenuates the influence of neonatal maternal deprivation on the behavior of adolescent white rats

Maternal deprivation in the early postnatal period significantly affects the behavior and development of different animals. Here we studied delayed effects of daily maternal deprivation (5 h/day) on physical development and behavior of white rats during postnatal days 1 to 14. Here we studied the possibility of reducing the negative consequences of deprivation by daily intranasal treatment with Semax, an analog of ACTH(4-10), in a dose of 0.05 mg/kg from postnatal days 15 to 28. It was found that maternal deprivation decelerated the growth of young rats, boosted physical activity and emotional reactivity in novel environment, and increased anxiety in one-month-old animals. Semax weakened the impact of deprivation on animal body weight and normalized the levels of anxiety in rats.

Formation of spatial memory in rats with ischemic lesions to the prefrontal cortex; effects of a synthetic analog of ACTH(4-7)

Photochemically induced thrombosis of blood vessels in the prefrontal cortex in rats was shown to lead to ischemic infarcts in the lesion zone. Bilateral ischemic lesioning of the prefrontal cortex degraded measures of spatial memory when animals were tested in a Morris water maze with an invisible platform 20-24 days after surgery. Chronic intranasal administration of the peptide Met-Glu-His-Phe-Pro-Gly-Pro (Semax), a synthetic analog of ACTH(4-7), at a dose of 250 microg/kg/day during the first six days after photothrombosis, led to recovery of the animals' learning ability. The long-term antiamnestic action of the peptide observed here may result from its neuroprotective activity and its ability to stimulate the synthesis of neurotrophic factors.

Semax and Pro-Gly-Pro activate the transcription of neurotrophins and their receptor genes after cerebral ischemia

Consisting of a fragment of ACTH(4-7) and C-terminal PGP tripeptide, the polypeptide Semax is successfully used for acute stroke therapy. Previous experiments showed rapid induction of Bdnf, Ngf, and TrkB expression in intact rat hippocampus following Semax treatment. To investigate the mRNA expression of neurotrophins and their receptors after treatment with either Semax or PGP, the rat brains were analyzed at three time points following a permanent middle cerebral artery occlusion (pMCAO). We have shown for the first time that both Semax and PGP activate the transcription of neurotrophins and their receptors in the cortex of rats subjected to pMCAO. The profiles of transcription alteration under PGP and Semax treatment were partially overlapped. Semax enhanced the transcription of Bdnf, TrkC, and TrkA 3 h after occlusion, Nt-3 and Ngf 24 h after occlusion, and Ngf 72 h after occlusion. PGP enhanced the transcription of Bdnf and TrkC 3 h after pMCAO and Ngf, TrkB, TrkC, and TrkA 24 h after pMCAO. The analysis of the transcription alterations under PGP and Semax treatment in the cortex of rats without surgery, sham-operated rats and rats subjected to pMCAO revealed that Semax selectively affected the transcription of neurotrophins and their receptors in the ischemic rat cortex, whereas the influence of PGP was mainly unspecific.

Effects of behaviorally active ACTH (4-10) analogue - Semax on rat basal forebrain cholinergic neurons

PURPOSE

It is well established that cholinergic neurons of the basal forebrain degenerate in Alzheimer's dementia. Although recent studies were concentrated on screening molecules that might reduce the concomitant cell loss, little is known about therapeutically promising molecules. We studied the effect of Semax (Met-Glu-His-Phe-Pro-Gly-Pro), a behaviorally active adrenocorticotropic hormone (4-10) analogue, on survival of cholinergic basal forebrain neurons in vitro. Semax is known to stimulate learning and memory and can be successfully used for treatment of ischemic stroke.

METHODS

Primary cultures of neuronal and glial cells from basal forebrain of rats were used in all experiments. The stability of Semax in cell cultures was tested by HPLC analysis. Cell survival in neuronal cultures was quantitated using immocytochemical and cytochemical analyses as well as detection of choline acetyltransferase activity.

RESULTS

We have shown that Semax may approximately 1.5-1.7 fold increase survival of cholinergic basal forebrain neurons in vitro. Moreover, Semax (100 nM) stimulated activity of choline acetyltransferase in dissociated basal forebrain tissue cultures. However, the numbers of GABA-ergic neurons, total neuron specific enolase neurons were not affected. In concentration from 1 nM to 10 microM, Semax did not affect proliferation of glial cells in primary cultures.

CONCLUSION

Implications of these findings with respect to Alzheimer's disease remain to be clarified.