Semax in rat glial cell cultures: NGF and BDNF mRNA induction, a published study summary

Summary

This summary describes a 2001 study in Neuroscience Letters by Shadrina and colleagues at the Institute of Molecular Genetics, Moscow, and a 2006 study in the Journal of Neurochemistry by Dolotov and colleagues from the same institute. Shadrina and colleagues measured nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) mRNA in glial cell cultures prepared from the basal forebrain of newborn rats after the heptapeptide Semax was added to the medium. Dolotov and colleagues measured the binding of tritium-labelled Semax to cell membranes isolated from rat basal forebrain and reported a dissociation constant and binding capacity.

Peptide

Name

Semax

Sequence

Met-Glu-His-Phe-Pro-Gly-Pro

CAS

80714-61-0

Formula

C₃₇H₅₁N₉O₁₀S, approximately 813.9 g/mol

Class

Synthetic heptapeptide analogue of the adrenocorticotropic hormone fragment ACTH(4-10), in which the C-terminal part of the fragment is replaced by Pro-Gly-Pro.

Study design

Model system (Shadrina 2001): primary glial cell cultures obtained from the basal forebrain of newborn rats.

Groups: cultures with Semax added to the medium compared with control cultures. Samples were taken at several time points after addition, the earliest being 30 minutes. The peptide was present only in the culture medium.

Endpoints measured: NGF and BDNF mRNA levels, expressed relative to control cultures. The earlier work by the same group on neuronal cell survival in culture, which prompted the mRNA experiment, is referred to in the paper but was not re-measured here.

Model system (Dolotov 2006, binding arm): cell membranes isolated from rat basal forebrain, incubated with tritium-labelled Semax. Binding was examined for time dependence, specificity, reversibility and calcium dependence, and saturation analysis gave a dissociation constant (KD) and a maximal binding capacity (Bmax). The same paper also contains an in-vivo arm that is not summarised here.

Companion paper (Agapova 2007): NGF and BDNF gene expression measured by real-time PCR in several regions of rat brain one hour after the animals received Semax; cited for completeness, not summarised.

Reported findings

Shadrina and colleagues reported changes in mRNA levels for both the NGF and BDNF genes in the glial cultures. The greatest increase was found 30 minutes after the peptide was added: at that time BDNF mRNA was eightfold higher than in control cultures and NGF mRNA was fivefold higher.

Dolotov and colleagues reported that binding of tritium-labelled Semax to basal forebrain membranes was time dependent, specific and reversible, and required calcium ions. The mean dissociation constant was 2.4 plus or minus 1.0 nM (mean plus or minus SEM) and the Bmax was 33.5 plus or minus 7.9 fmol per mg protein. The authors interpreted these values as evidence of specific binding sites for the peptide in that brain region.

Time-course data beyond the 30-minute point, group sizes and statistical tests are in the full papers and are not reproduced here.

Limitations

Both studies come from a single institute. The 2001 study is a cell-culture experiment on mixed glial cultures from newborn animals and reports mRNA, not protein. The binding study characterises a membrane preparation and does not identify the binding protein; a dissociation constant from a membrane fraction is not the same as a cloned-receptor affinity. In-vivo arms of the cited papers are not summarised here. No human data are summarised.

References

1. Shadrina MI, Dolotov OV, Grivennikov IA, Slominsky PA, Andreeva LA, Inozemtseva LS, Limborska SA, Myasoedov NF. Neuroscience Letters. 2001;308(2):115-118. PMID 11457573. DOI 10.1016/s0304-3940(01)01994-2.
2. Dolotov OV, Karpenko EA, Seredenina TS, et al. Journal of Neurochemistry. 2006;97 Suppl 1:82-86. PMID 16635254. DOI 10.1111/j.1471-4159.2006.03658.x.
3. Agapova TY, Agniullin YV, Shadrina MI, Shram SI, Slominsky PA, Lymborska SA, Myasoedov NF. Neuroscience Letters. 2007;417(2):201-205. PMID 17353092. DOI 10.1016/j.neulet.2007.02.042.