Download THE ORIGIN OF NOCICEPTION ALTERATION IN RATS TREATED

ALTERED NOCICEPTION IN THE EXPERIMENTAL MODEL OF
ALZHEIMER’S DISEASE; NOXA-DEPENDENT DIFFERENCES
Melita Šalković-Petrišić, Ivana Ferber and Zdravko Lacković
Department of Pharmacology, Medical School and Croatian Institute for Brain
Research, University of Zagreb, Šalata 11, 10 000 Zagreb, Croatia
AIMS: Intracerebroventricular (icv) administration of low streptozotocin doses
produces long-term and progressive deficits in cognitive behaviour and cerebral
glucose and energy metabolism, resembeling those found in the brain of patients with
Alzheimer’s disease. Therefore, streptozotocin icv treated rats have been proposed as
an appropriate experimental model of sporadic Alzheimer’s dementia. We have
investigated nociception in the streptozotocin icv (0.5 -1 mg/kg) treated rats during
the eight week long post-treatment period.
METHODS: Spontaneous pain threshold has been measured following the thermallyand mechanically-induced pain stimulus in the hot plate (55  0.5oC) and the paw
pressure test, respectively.
RESULTS: Spontaneous pain treshold in streptozotocin icv treated rats following the
thermally-induced pain stimulus demonstrated increased values ≤25% in comparison
to the respective controls within the observed period. Statistically significant
increment was seen as early as two weeeks after the drug treatment, with plato values
reached in the fourth week and a tendency of returning to the normal values
afterwards. However, pain treshold following the mechanically-induced pain stimulus
was decreased (-19 to -36%) in streptozotocin icv treated rats, in comparison to the
controls, with decrement being statistically significant from the first to the eights
week after the drug treatment.
CONCLUSION: Streptozotocin icv treated rats that represent the experimental model
of sporadic Alzmeir's disease have altered nociception that depends on the nature of
pain stimulus, being different following the thermal and mechanic noxa. Whether this
effect is related to the specific and selective toxicity of streptozotocin for certain
molecular structures or to the consequently induced cerebral neurochemical disorders,
remains to be elucidated.
Supported by the projects of the Croatian Ministry of Science and Technology
(0108253 and 108134).