PhD Scientific Days 2023

Translational Medicine - Posters O

On the path of establishing a viable neurovascular uncoupling model in rats

Text of the abstract

We aimed to establish a pharmacologically induced neurovascular uncoupling (NVU) method in rats as a translationally valid animal model of human cognitive decline.
Diminished neurovascular coupling (NVC) has been shown during aging and in various brain disorders. Pharmacologically induced NVU with subsequent neurological and cognitive defects was described in mice (Tarantini, 2015), however, no similar procedure has been reported so far in rats.
In our previous study (E1), we used 28 male Hannover Wistar rats. NVU was induced by intraperitoneal administration of a pharmacological “cocktail” consisting of N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide (MSPPOH, 5 mg/kg), L-NG-nitroarginine methyl ester (L-NAME, 10 mg/kg) and indomethacin (1 mg/kg) and injected twice daily for 8 consecutive days. In a follow-up experiment (E2) with 17 rats, we repeated the same protocol, using halved doses.
In E1, animals were tested in Morris water-maze and fear-conditioning assays, whereas in E2, they performed in novel object recognition, lever-press and spontaneous alternation tasks. Blood pressure was monitored by tail-cuffs. NVC was measured in the barrel cortex in a non-recovery operation. A laser Doppler probe was used to detect changes in cerebral blood-flow (CBF), while the contralateral whisker pad was stimulated. Brain and small intestine tissue samples were collected post mortem. Samples from E1 have already been processed for prostaglandin E2 (PGE2) level determination, while measurement of brain EET levels is currently underway.
Animals treated with the “cocktail” showed no impairment in their performance in any of the cognitive tasks. However, in E1, they showed ~50 % less increase in CBF and an overall higher blood pressure. Intestinal bleeding and ulcers were found in some of them, and ELISA assays revealed significantly decreased levels of PGE2 in the brain and small intestine. In E2, we did not observe significant changes either in blood-pressure or intestinal autopsy or in CBF.
We could evoke NVU by the applied mixture of pharmacons in E1, but the treatment also induced hypertension and intestinal alterations. By halving the doses we could avoid these side effects but also lost efficacy. Thus, further refinements are required for the development of an applicable model, mostly with regard to finding the appropriate dosages and learning assays.