Abstracts from The Federation of European Neuroscience Societies (FENS) 2018

F055 Behavioral effects of immunotoxin 192IgG-saporin depends on the type of its administration to rats.
Yulia Dobryakova, Alexey Bolshakov, Maria Zaichenko, Mikhail Stepanichev, Vlaimir Markevich
featuring IT-01 192-IgG-SAP (Sunday 2:00pm-5:30pm)

It is known that degeneration of cholinergic neurons is one of key events during development of Alzheimer’s disease. We used immunotoxin 192IgG-saporin, a conjugate of antibody to p75/NFGR receptor with saporin, to induce the cholinergic deficit in the hippocampus. Here, we compared effects of intracerebroventricular (i.c.v.) and intraseptal injection of 192IgG-saporin on the learning performance in rats. Immunohistochemical analysis of the ChAT stained sections showed that both types of 192IgG-saporin injection led to a strong loss ChAT-positive neurons in septal area compared to control. Behavioral testing began 3 weeks after the injection.

We found that, in Morris Water Maze, i.c.v. injected rats had longer latencies to reach the platform and higher distance swam compared to control when the animals learned to find platform. We found that during probe trial, when the platform was removed from the maze, i.c.v.-treated rats spent significantly less time in a quadrant, where the platform was during training, and swam shorter distance in it, as compared to the control animals. Rats treated intraseptally with the immunotoxin had no behavioral deficits in the Morris Water Maze. In the beam walking test both groups of rats showed small but significant reduction of motor performance (p<0.05). In contrast, locomotor and exploratory activity in the open field task was affected only by intraseptal toxin administration as compared to the control. In conclusion, our data suggest that different types of immunotoxin administration leads to different disturbances in behavior.
The work was supported by Grant of Russian Science Foundation No 16-15-10403.

C038 Improvements in cognitive function after focused ultrasound are associated with changes in hippocampal cholinergic activity and neurogenesis.
Jaewoo Shin, Chanho Kong, Jihyeon Lee, Young Cheol Na, Won Seok Chang, Jin Woo Chang
featuring  IT-01 192-IgG-SAP (Monday 9:30am-1:00pm)

Introduction: Alzheimer’s disease is irreversible and progressive neurodegenerative disorder that destroys memory and cognitive function. Recently, focused ultrasound (FUS) has been demonstrated that FUS- mediated BBB opening induces an increase in hippocampal neurogenesis in adult rodents. In this study, we investigated the effects of FUS on memory and cognitive function after 192 IgG-saporin lesioning.

Materials and Methods: The present study utilized adult male Sprague-Dawley rats (200-250 g). Animals were divided into the three groups: Sham group (PBS injection), Lesion group (saporin injection), FUS group (saporin + FUS treatment). Lesion groups were injected bilaterally into the lateral ventricle. Rats were sonicated by using a single-element transducer with microbubble. The acoustic parameters for each sonication are: pressure amplitude 0.3 MPa, pulse length 10 ms, burst repetition frequency 1 Hz, and a duration of 120 s. BrdU was intraperitoneally injected 2 times per day for 4 consecutive days starting 24 hours after sonication. Two weeks after IgG-saporin administration, spatial memory was tested with the Morris water maze training.

Results: In the water maze test, the FUS groups were significantly increased in number of crossing and platform zone, compared to the lesion group. We confirmed that the number of BrdU+, DCX+, and NeuN+ were significantly increased in the dentate gyrus following FUS sonication, compared to the lesion groups.
Conclusion: Our results suggest that FUS treatments led to spatial memory improvement in cholinergic deficits rat model. These provided evidences indicate that reason of the behavior change may be induced by increase of acetylcholine activity and neuronal plasticity.

F038 Expression of NR2B subunit of the NMDA receptor and spatial long-term memory in medial septal lesioned rats.
L Kruashvili, M Dashniani, G Beselia, N Chkhikvishvili
featuring IT-32 GAT1-SAPIT-01 192-IgG-SAP (Monday 9:30am-1:00pm)

The present study was designed to investigate the effect of selective immunolesions of cholinergic and GABA- ergic SH projection neurons (using 192 IgG-saporin and GAT-1 saporin, respectively) on spatial memory assessed in water maze and the N-methyl-D-aspartate (NMDA) receptor GluN2B subunit expression in the rat hippocampus. Animals were tested in a standard Morris water maze. We found that immunolesion of medial septal cholinergic neurons did not affect spatial learning as exhibited by a decreased latency to find the hidden platform across the eight training trials. In contrast, rats with immunolesions of medial septal GABAergic neurons did not show a decreased latency across training trials in water maze. Trained control rats spent significantly longer than chance (15 s) performances such as swimming time in test sector (where the hidden platform was located). Moreover, they spent significantly longer in test sector than in the opposite sector, confirming the establishment of long-term memory. In contrast, the preference for test sector was abolished in medial septal immunolesioned rats. Because Saporin treated rats learned the location of the hidden platform during training, the results suggest that saporin treated rats could not remember the training a day later. We found that the expression level of NR2B subunit of NMDA receptor in the hippocampus was decreased significantly in the GAT-1 treated group compared with the control and saporin treated groups. In conclusion, our findings suggest that immunolesion of medial septal GABAergic neurons can interrupt hippocampus-dependent spatial learning, possibly through modulation of NMDA receptor subunit expression in the hippocampus.

F044 Effects of lesions of medial septal area on spatial short-term memory.
Khatuna Rusadze, Reniko Sakandelidze, Mariam Chighladze
featuring IT-32 GAT1-SAPIT-01 192-IgG-SAP (Tuesday 2:00pm-5:30pm)

In the present study electrolytic and the immunotoxins (192 IgG saporin and GAT1-SAP) lesions of medial septal area (MS) were used to investigate the importance of cholinergic and GABAergic MS neurons in spatial working memory using spatial alternation task. In our experiments electrolytic lesions destroyed on average 69% of the intact MS. Examination of the AChE stained sections showed that after injections of 192 IgG saporin into the MS, animals exhibited significantly less AChE staining in MS as compared to sections obtained from control animals. Intraseptal GAT1-SAP preferentially reduced GABAergic neurons as compared to cholinergic neurons in the MS. The results of present study indicate that spatial short-term memory is affected only by electrolytic but not 192 IgG saporin or GAT1-SAP lesions. The behavioral testing showed that 192 IgG saporin treated rats, relative to control rats, had a significantly lower level in the number of arms entered during the testing session. However, the groups did not differ in the level of alternation behavior. GAT1-SAP lesioned rats showed that the percent alternation scores and the number of arms that the rat entered in the maze were not significantly different from control rats.