Recording of behavioural responses after unilateral injection of MSM peptides into the rat left ventral tegmental area
S. Svirskis1, B. Opmane2 and V. Klusa1
1University
of Latvia, Riga, Latvia
2Latvian Institute of Organic Synthesis, Riga, Latvia
Our studies are focused on detailed examination of behavioural responses induced by alpha-, gamma1- and gamma2-MSH administered into the ventral tegmental area (VTA) in rats by use of the registration system The Observer with the Psion Workabout handheld computer (Noldus Information Technology, The Netherlands).
Since the VTA represents the brain region containing A10 mesolimbic dopaminergic neurons, increased dopamine release from their projections in the nucleus accumbens and tuberculum olfactorium can be taken as essential to provide manifestation of intensified behavioural responses, such as stereotypic ones. Our previous data [1] showed that MSH peptides are capable to alter locomotor responses after intra-VTA administration in rats.
In the present studies attention was payed to the following responses: face washing (FW), body grooming (BG), ano-genital grooming (AAG), tail licking (TL), scratching (SCR), head shakes (HS), wet-dog shakes (WDS), also rearing or vertical activity (VA), locomotion or horizontal activity (HA), rotations (ROT) and catalepsy (CAT). The total observation was performed during 1 h. To find out the dynamics, these responses were summarized in 15-min intervals during the whole observation period and calculated as mean ± SEM.
The Observer allowed us to record the full spectrum of behavior events. So, the alpha-MSH and gamma1-MSH in comparison to saline induced excessive stereotypic responses, such as grooming (particularly FW, BGF, SCR), as well as increased VA. The observed intensified grooming responses were maintained for 30-45 min after peptide injections, whereas VA only for 15 min. In contrast, gamma2-MSH lacked these activities, but it caused a moderate (5 scores from 10 as maximum) CAT. In addition, only gamma1-MSH elicited slight ROT.
One may conclude that The Observer registration and analysis system combined with the Psion Workabout handheld computer as a mobile tool for behavioral data collection gave a good possibility to obtain a clear picture of the quantitative and qualitative changes in MSHs-induced behavioural repertoire in rats.
Poster presented at Measuring Behavior 2000, 3rd International Conference on Methods and Techniques in Behavioral Research, 15-18 August 2000, Nijmegen, The Netherlands