Social Investigation and Long-Term Recognition Memory Performance in 129S1/SvImJ and C57BL/6JOlaHsd Mice and Their Hybrids

Abstract

When tested for their behavioural performance, the mixed genetic background of transgenic mice is a critical, but often ignored, issue. Such issues can arise because of the significant differences in defined behavioural parameters between embryonic stem cell donor and recipient strains. In this context, the commonly used stem cell donor strain ‘129’ shows ‘deficits’ in different paradigms for learning and long-term memory. We investigated the long-term social recognition memory performance and the investigative behaviour in commercially available 129S1/SvImJ and C57BL/6JOlaHsd mice and two F1-hybrids (129S1/SvImJ×C57BL/6JOlaHsd) by using the social discrimination procedure and its modification, the volatile fraction cage (VFC). Our data revealed an unimpaired olfactory long-term recognition memory not only in female and male 129S1/SvImJ and C57BL/6JOlaHsd mice but also in the two hybrid lines (129S1/SvImJxC57BL/6JOlaHsd) when the full ‘olfactory signature’ of the ‘to-be-recognized’ conspecific was presented. Under these conditions we also failed to detect differences in the long-term recognition memory between male and female mice of the tested strains and revealed that the oestrus cycle did not affect the performance in this memory task. The performance in the VFC, based only on the volatile components of the ‘olfactory signature’ of the ‘to-be-recognized’ conspecific, was similar to that observed under direct exposure except that females of one F1 hybrid group failed to show an intact long-term memory. Thus, the social discrimination procedure allowing direct access between the experimental subject and the stimulus animal(s) is highly suitable to investigate the impact of genetic manipulations on long-term memory in male and female mice of the strain 129S1/SvImJ, C57BL/6JOlaHsd and 129S1/SvImJxC57BL/6JOlaHsd hybrids.

Timing of presentation and nature of stimuli determine retroactive interference with social recognition memory in mice

“…Juvenile mice of both sexes of the C57BL/ 6JOlaHsd strain (25-38 days old) were used as a social stimulus. Extensive previous studies revealed that neither the age nor the sex of the juvenile significantly affects the recognition abilities of male adult experimental subjects [9,10].…”

“…[7][8][9]) and, therefore, considered to be suitable for our experiments. They were housed in groups of five per cage (size: 20 × 37 × 15 cm) under standard laboratory conditions with a 12 h:12 h light-dark cycle (light on: 07:00) for at least one week before starting the experiments.…”

The Role of the Dopaminergic Cells of the Median Raphe Region in the Behavior of the Male Mice

“…The mice were group housed (2-3 mice/cage) till the beginning of the behavioral examination, when individual housing began to enhance social interest. Male juvenile (30-45-day-old) C57BL/6J mice were used as stimulus animals for the sociability and resident intruder test as previously suggested [90,91]. For RT-PCR C57BL/6J adult male mice were used from the same local colony.…”

The Dopaminergic Cells in the Median Raphe Region Regulate Social Behavior in Male Mice

“…The mice were group housed (2-3 mice/cage) until the beginning of the behavioral examination, when individual housing began to enhance social interest. Male juvenile (30-45-day-old) C57BL/6J mice were used as stimulus animals for the sociability and resident intruder tests as previously suggested [92,93]. For RT-PCR, C57BL/6J adult male mice from the same local colony were used.…”