Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2004 Jan 21;24(3):692-701.
doi: 10.1523/JNEUROSCI.4781-03.2004.

Overexpression of adenosine kinase in epileptic hippocampus contributes to epileptogenesis

Nicolette Gouder  1 , Louis Scheurer, Jean-Marc Fritschy, Detlev Boison
Affiliations

Overexpression of adenosine kinase in epileptic hippocampus contributes to epileptogenesis

Nicolette Gouder et al. J Neurosci. .

Abstract

Endogenous adenosine in the brain is thought to prevent the development and spread of seizures via a tonic anticonvulsant effect. Brain levels of adenosine are primarily regulated by the activity of adenosine kinase. To establish a link between adenosine kinase expression and seizure activity, we analyzed the expression of adenosine kinase in the brain of control mice and in a kainic acid-induced mouse model of mesial temporal lobe epilepsy. Immunohistochemical analysis of brain sections of control mice revealed intense staining for adenosine kinase, mainly in astrocytes, which were more or less evenly distributed throughout the brain, as well as in some neurons, particularly in olfactory bulb, striatum, and brainstem. In contrast, hippocampi lesioned by a unilateral kainic acid injection displayed profound astrogliosis and therefore a significant increase in adenosine kinase immunoreactivity accompanied by a corresponding increase of enzyme activity, which paralleled chronic recurrent seizure activity in this brain region. Accordingly, seizures and interictal spikes were suppressed by the injection of a low dose of the adenosine kinase inhibitor 5-iodotubercidin. We conclude that overexpression of adenosine kinase in discrete parts of the epileptic hippocampus may contribute to the development and progression of seizure activity.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Specificity of the anti-ADK antiserum. A, Western blot analysis of aqueous protein extracts derived from various organs from P4 pups from an Adk+/- x Adk+/- intercross. Extracts corresponding to 25 μg of total protein each from wild-type (Adk+/+), heterozygous (Adk+/-), and homozygous (Adk-/-) mutant pups were probed with a polyclonal rabbit antiserum raised against recombinant mouse ADK. H, Heart; K, kidney; Lu, lung; B, brain; Li, liver. B, Part of coronal brain section of an Adk+/+ pup taken at P4 and stained with diaminobenzidine hydrochloride (DAB) for ADK immunoreactivity. C, Part of a transverse brain section of a mutant Adk-/- pup taken at P4 and stained with DAB for ADK immunoreactivity. Note the lack of ADK staining in the brain taken from the knock-out animal. D-G, Insets are magnified in the corresponding panels. Scale bars: (in B) B, C, 350 μm; (in F) D-G, 50 μm.
Figure 2.
Figure 2.
Photographs of ADK immunoreactivity in transverse and parasagittal brain sections of an adult Adk+/+ mouse, processed for immunoperoxidase staining. A, Transverse section of a brain hemisphere showing a rather homogenous distribution of individual cells expressing ADK. B, Neocortex at higher magnification (see inset in A) showing an even distribution of ADK-positive cells in all cortical layers. C, Striatum and globus pallidus at higher magnification (see inset in A) showing individual ADK-positive cells. D, E, Olfactory bulb at higher magnification taken from a parasagittal section. Note the strong staining of ADK-positive neurons (D) and their processes in glomeruli (E). F, Cerebellum at higher magnification taken from a parasagittal section. Note the concentration of ADK-positive cells in the molecular layer. Scale bars: A, 800 μm; (in B), B, C, F, 135 μm; (in D), D, E, 90 μm.
Figure 3.
Figure 3.
Changes in hippocampal cytoarchitecture ADK immunoreactivity during the course of epileptogenesis. Brains from KA-treated mice were taken at different time points after either intrahippocampal KA or saline injection (n = 4 animals for each time point). Transverse brain sections of the KA-injected brain hemisphere were stained with either cresyl violet (A-E) or for ADK immunoreactivity (F-O). F-J, Ipsilateral side; K-O, Contralateral side. A, F, K, Two hours after saline injection. B, G, L, Two hours after KA injection. C, H, M, One day after KA injection. D, I, N, One week after KA injection. E, J, O, Four weeks after KA injection. Note the biphasic regulation of ADK immunoreactivity after intrahippocampal KA injection (F-J). An initial loss of ADK immunoreactivity within 2 hr after KA injection (G) is gradually followed by a significant overexpression (J), which becomes also evident, although to a lesser degree, within the contralateral hippocampus (O). Scale bar: (in O), A-O, 1000 μm.
Figure 4.
Figure 4.
Colocalization of ADK and GFAP immunofluorescence, as seen by confocal laser-scanning microscopy. Transverse brain sections of a KA-injected animal taken 4 weeks after the injection and those from a naive control animal were double-stained for ADK (red) and the astrocyte marker GFAP (green). Optical sections were digitized at high magnification and superimposed for display. A, CA1 of a control animal. Note the red nuclei stained for ADK and astrocytic processes stained for GFAP (green). B, CA1 of a KA-injected animal. Note the characteristic pattern of gliosis characterized by an increase of astrocytic processes and by a spread of ADK immunoreactivity into the processes (colocalization of ADK and GFAP, yellow). C, Dentate gyrus of a control animal. Note that the cell bodies of individual astrocytes (green processes) are stained for ADK. D, Dentate gyrus of a KA-injected animal. Note the massive gliosis characterized by the swelling of cell bodies, the enlargement of astrocytic processes, and the expansion of ADK immunoreactivity into the processes (colocalization of ADK and GFAP, yellow). E, Same as in C showing ADK immunofluorescence only, which is mainly confined to the nucleus. F, Same as in D showing ADK immunofluorescence only, which becomes evident in astrocytic processes. so, Stratum oriens; sp, stratum pyramidale; sr, stratum radiatum; sml, stratum moleculare; sg, stratum granulosum; hi, hilus. Scale bar: (in F), A-F, 30 μm.
Figure 5.
Figure 5.
Increase of ADK enzyme activity in epileptic hippocampus. KA-injected and contralateral hippocampi were dissected out, homogenized, and analyzed in an enzyme coupled bioluminescent assay 8 weeks after the lesion (n = 5 mice). Hippocampi (n = 10) from age-matched naive mice (n = 5) were dissected as controls. Adenosine kinase enzyme activity, measured as phosphorylation of nanograms of adenosine per minute per milligram of protein, was determined by the increase of relative light units per time. The results were normalized to the ADK activity found in naive control hippocampi (100%). Samples from both KA-injected and contralateral hippocampi displayed a significant increase in ADK activity of 177.2 ± 16% and 142.4 ± 21.9%, respectively. Data were analyzed by a Kruskal-Wallis test (p < 0.001), and paired comparisons were done with Mann-Whitney U tests (**p < 0.01; *p < 0.05). Means are given with ± SDs.
Figure 6.
Figure 6.
Seizure suppression by 5-iodotubercidin. Representative intrahippocampal EEG recordings taken from one animal before and after intraperitoneal injection of 5-iodotubercidin and DPCPX. Four weeks after kainic acid treatment 5-iodotubercidin was administered, followed after 60 min by DPCPX (n = 5 animals). The animals were recorded for a total of 2 hr before and 6 hr after 5-iodotubercidin injection. Representative sections of 120 sec duration (top traces) are displayed. Close-up views of 10 sec each are displayed in the bottom traces. The recordings displayed were performed on the same animal 1 hr before 5-iodotubercidin injection (A) (note the occurrence of high-amplitude and high-frequency discharges) 30 min after 5-iodotubercidin injection (B) (3.1 mg/kg, i.p.) (note the suppression of seizure activity), and 30 min after DPCPX (C) (1 mg/kg i.p.) (note the recurrence of full seizure activity).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Boison D, Scheurer L, Tseng JL, Aebischer P, Mohler H (1999) Seizure suppression in kindled rats by intraventricular grafting of an adenosine releasing synthetic polymer. Exp Neurol 160: 164-174. - PubMed
    1. Boison D, Huber A, Padrun V, Déglon N, Aebischer P, Möhler H (2002a) Seizure suppression by adenosine releasing cells is independent of seizure frequency. Epilepsia 43: 788-796. - PubMed
    1. Boison D, Scheurer L, Zumsteg V, Rülicke T, Litynski P, Fowler B, Brandner S, Mohler H (2002b) Neonatal hepatic steatosis by disruption of the adenosine kinase gene. Proc Natl Acad Sci USA 99: 6985-6990. - PMC - PubMed
    1. Bontemps F, Van den Berghe G, Hers HG (1983) Evidence for a substrate cycle between AMP and adenosine in isolated hepatocytes. Proc Natl Acad Sci USA 80: 2829-2833. - PMC - PubMed
    1. Bouilleret V, Ridoux V, Depaulis A, Marescaux C, Nehlig A, Le Gal La Salle G (1999) Recurrent seizures and hippocampal sclerosis following intrahippocampal kainate injection in adult mice: electroencephalography, histopathology and synaptic reorganization similar to mesial temporal lobe epilepsy. Neuroscience 89: 717-729. - PubMed

Publication types

MeSH terms

LinkOut - more resources