Investigations of hippocampal astrocytes in lipopolysaccharide-preconditioned rats in the pilocarpine model of epilepsy.

The present paper is the first work to determine the effect of lipopolysaccharide (LPS) in the pilocarpine model of epilepsy on the morphology of rat hippocampal astrocytes in vivo. The study involved adult male Wistar rats, which 72 hours prior to administration of pilocarpine hydrochloride (PILO) were intraperitoneally (ip) preconditioned with LPS at a dose of 0.5 mg/kg b.w. The control animals were administered (ip) saline or LPS alone. The astrocytes in the control animals displayed characteristic stellate morphology. Examinations of the astrocytes were performed on days one, three and 21 of the pilocarpine model of epilepsy (i.e. in the acute, silent and chronic periods). The astrocytes of the CA1 and CA3 pyramidal layers of the hippocampus were observed and analyzed at the structural and ultrastructural levels. It was demonstrated that on days one and three, glial cells from both the nonpreconditioned and the LPS-preconditioned animals displayed similar reactive changes, manifesting themselves as swelling of cell bodies, glial processes, and astrocytosis. Moreover, reduction in cell organelles aggregated at one pole and the presence of vacuoles were observed. The most pronounced astrogliosis and cell swelling occurred on day 21. We conclude that LPS has no effect on the morphology of astrocytes in the pilocarpine model of epilepsy, unlike the results obtained by other authors in vitro.

Behavioural and histological effects of preconditioning with lipopolysaccharide in epileptic rats.

Sublethal stress stimuli such as systemic endotoxin treatment can induce tolerance of the brain to subsequent ischemic stress, which results in a decreased infarct size. Based on this evidence, we hypothesized that lipopolysaccharide (LPS)-induced preconditioning could protect hippocampal neurons in epileptic rats. To test this hypothesis, the anticonvulsant effect of a low dose of LPS against seizures elicited by pilocarpine hydrochloride was measured. Using the pilocarpine model of temporal lobe epilepsy and LPS-preconditioning, we also investigated hippocampal pathology in the rat brain. Based on the behavioural observations conducted, it can be assumed that the preconditioning procedure used may decrease seizure excitability in epileptic rats. However, determination of the seizure excitability threshold needs to be elaborated. Qualitative and quantitative analyses of histological brain sections in the LPS-preconditioned rats showed markedly decreased intensity of neurodegenerative changes in the CA1, CA3 and DG hippocampal fields. The tendency was observed in all the periods of the pilocarpine model of epilepsy. We suggest that preconditioning with LPS may have neuroprotective effects in the CA1, CA3 and DG hippocampal sectors; however, it has no influence on the course of the seizures in rats in the pilocarpine model of epilepsy.

Histological examination of the retinal ganglion layer in rabbits after experimental administration of the new immunosuppressive medicine--Cladribine.

The experiment was carried out on rabbit females of New Zealand breed weighing about 3 kg. Animals from the experimental group received Cladribine according to the schema of experimental treatment in the hairy cell leukemia and rabbits from the experimental group II--according to the schema of experimental treatment in multiple sclerosis. Specimens of retina were collected for histological examinations in the light microscope. It was revealed that administration of Cladribine in the dose corresponding to the therapeutic dose used in human for the treatment of the hairy cell leukemia and multiple sclerosis does not cause evident morphological changes in retinal ganglion cells on the level of light microscope.

Ultrastructural changes of retinal ganglion cells in rabbits of New Zealand breed after experimental administration of 2-CDA (Cladribine).

The experiment was carried out on rabbit females of New Zealand breed weighing about 3 kg. The animals from the experimental group received. Cladribine in the dose of 0.1 mg/kg for 7 days. Specimens of retina were collected for ultrastructural examinations. It was revealed that administration of Cladribine in the dose corresponding to the therapeutic dose used in human for the treatment of the hairy cell leukemia causes morphological changes in ultrastructure of retinal ganglion cells which are classified as reversible in cytophysiology. The necessity of periodic, regular ophthalmological examinations during Cladribine treatment was indicated.