Semax, an analogue of adrenocorticotropin (4–10), is a potential agent for the treatment of attention-deficit hyperactivity disorder and Rett syndrome

Effect of a neurostimulator on postnatal neurogenesis in rodent olfactory bulbs

The aim of the study was to reveal the effect of neurostimulation with the TKPRPGP neuropeptide on the expression intensity of Doublecortin and Nestin in the olfactory bulb of white Wistar rats using immunohistochemical and computer analysis methods. An isolated assessment of early progenitor differentiation by the density of nestin-positive structures showed that stimulation from birth to 14 days preserves the level of nestin expression, preventing its decrease. When the administration of the neuropeptide is stopped, the expression of nestin decreases sharply, starting from the central zones of the bulb, and after three weeks it is no longer present. The dynamics of doublecortin positive structure density reflects an increase upon neuropeptide administration. Each course of neuropeptide administration caused an increase in the density of the marker, but the degree of effectiveness decreased with age, and the duration of the effect decreased. In conclusion, administration of the neuropeptide TKPRPGP to rats at an early age prolongs the expression of nestin and doublecortin in the olfactory bulbs of rats up to 35 days and up to 74 days of observation, respectively. The administration of the neuropeptide in adulthood does not lead to re-expression of these markers.

Effects of Semax on the Default Mode Network of the Brain

The effects of nootropic drug Semax on the neuronal network of the brain were studied by the resting state functional magnetic-resonance imaging (resting state fMRI). The study was carried out on two groups of healthy volunteers (11 men and 13 women aged 43.9±9.5 years). Resting state fMRI was carried out 3 times: directly before and 5 and 20 min after intranasal 1% Semax (14 subjects) or placebo (10 subjects). The topography of the resting state default mode network was studied. A greater volume of the default mode network rostral (medial frontal cortex) subcomponent was detected in the Semax group in comparison with controls. Resting state fMRI confirmed Semax effects on the neuronal network of the brain and demonstrated topography of these effects.

Biogenic amines in Rett syndrome: the usual suspects

Rett syndrome (RTT) is a severe postnatal neurological disorder caused by mutations in the methyl-CpG binding protein 2 (MECP2) gene. In affected children, most biological parameters, including brain structure, are normal (although acquired microcephaly is usually present). However, in recent years, a deficit in bioaminergic metabolism has been identified at the cellular and molecular levels, in more than 200 patients. Recently available transgenic mouse strains with a defective Mecp2 gene also show abnormalities, strongly suggesting that there is a direct link between the function of the MECP2 protein and the metabolism of biogenic amines. Biogenic amines appear to have an important role in the pathophysiology of Rett syndrome, for several reasons. Firstly, biogenic amines modulate a large number of autonomic and cognitive functions. Secondly, many of these functions are affected in RTT patients. Thirdly, biogenic amines are the only neurotransmitters that have repeatedly been found to be altered in RTT patients. Importantly, pharmacological interventions can be envisaged to try to counteract the deficits observed. Here, we review the available human and mouse data and present how they have been and could be used in the development of pharmacological treatments for children affected by the syndrome. Given our current knowledge and the tools available, modulating biogenic amine metabolism may prove to be the most promising strategy for improving the life quality of Rett syndrome patients in the short term.

Rett syndrome

Rett syndrome (RS) is an X-linked neurodevelopmental disorder and the second most common cause of genetic mental retardation in females. Different mutations in MECP2 are found in up to 95% of typical cases of RS. This mainly neuronal expressed gene functions as a major transcription repressor. Extensive studies on girls who have RS and mouse models are aimed at finding main gene targets for MeCP2 protein and defining neuropathologic changes caused by its defects. Studies comparing autistic features in RS with idiopathic autism and mentally retarded patients are presented. Decreased dendritic arborization is common to RS and autism, leading to further research on similarities in pathogenesis, including MeCP2 protein levels in autistic brains and MeCP2 effects on genes connected to autism, like DLX5 and genes on 15q11-13 region. This area also is involved in Angelman syndrome, which has many similarities to RS. Despite these connections, MECP2 mutations in nonspecific autistic and mentally retarded populations are rare.