Genetics, septal lesions, and avoidance behavior in mice

There is considerable evidence that the level of cerebral serotonin plays a key role in the volitional consumption of ethanol in both man and animals. Naive alcohol-preferring C57BL/6J mice have been shown to have a lower cerebral serotonin content compared to the non-preferring CBA/Ca mouse strain. This has been attributed to the enhancement of hepatic tryptophan pyrrolase activity in C57 mice. Activity and/or expression of tryptophan pyrrolase may be an important biological determinant of alcohol preference. We have investigated the possible mechanism/s underlying this strain difference in tryptophan pyrrolase activity by assaying both mRNA levels encoding for the tryptophan pyrrolase gene and by mutational analysis of tryptophan pyrrolase cDNA. We were unable to demonstrate any difference in tryptophan pyrrolase mRNA levels between naive C57 and CBA mice. Tryptophan pyrrolase mRNA levels were increased following starvation in C57 mice and following glucocorticoid administration in both C57 and CBA mice. Heteroduplex mutational analysis failed to detect any tryptophan pyrrolase cDNA sequence heterogeneity between these mice strains.

Reinforcing and Neurochemical Effects of Cocaine: Differences Among C57, DBA, and 129 Mice

All social animals, including humans, have different social identities that generate unique social interactions. Social preference behaviours, including social integration, prosocial behaviour, and cooperation, have a wide impact on an individual’s social life. However, the neural mechanisms underlying social preferences are not yet clear. In this study, using mice as model animals, we investigated strain preference, which is a social preference based on social identification. We revealed, for the first time, that the social behaviour strain preference of mice is heterogeneous; that is, C57 mice prefer to interact with mice of the same strain, whereas KM mice prefer to interact with mice of a different strain. We further confirmed that strain preference in mice can be plastically altered by changing the nurturing environment and increasing social exposure to mice of other strains. Finally, we screened brain regions related to mouse strain preference and revealed that the activity of the periaqueductal grey (PAG) was not only consistent with the social preference of both C57 and KM mice but also coordinated with the alteration in social preference. We subsequently used muscarine to inhibit the PAG in C57BL/6J mice and found that the strain-specific social preference in C57 mice disappeared. These results showed that the PAG is a key brain region for regulating strain preference and its plasticity. This work fills a gap in the study of strain preferences in social preference research.

The specificity of the histochemical NADPH diaphorase reaction for nitric oxide synthase-1 in skeletal muscles is increased in the presence of urea

Prey face a conflict between acquiring energy and avoiding predators and use both direct and indirect cues to assess predation risk. Illumination, an indirect cue, influences nocturnal rodent foraging behaviour. New Zealand holds no native rodent species but has introduced mice (Mus musculus) that severely impair native biodiversity. We used Giving-Up Densities (GUDs) and observations of foraging frequency and duration to assess if artificial light induces risk avoidance behaviour in mice and could limit their activity. We found both captive (wild strain) mice in outdoor pens and wild mice within a pest fenced sanctuary (Maungatautari, New Zealand) displayed avoidance behaviour in response to illumination. In captivity, total foraging effort was similar across lit and unlit pens but mice displayed a strong preference for removing seeds from dark control areas (mean: 15.33 SD: +/-11.64 per 3.5 hours) over illuminated areas (2.00 +/-3.44). Wild mice also removed fewer seeds from illuminated areas (0.42 +/-1.00 per 12 hours) compared to controls (6.67 +/-9.20). Captive mice spent less than 1.0% of available time at illuminated areas, versus 11.3% at controls; visited the lit areas less than control areas (12.00 +/- 9.77 versus 29.00 +/-21.58 visits respectively); and spent less time per visit at illuminated versus control areas (8.17 +/-7.83 versus 44.83 +/-87.52 seconds per visit respectively). Illumination could provide protection at ecologically sensitive sites, damaged exclusion fences awaiting repair, fence terminus zones of peninsula sanctuaries and shipping docks that service offshore islands. We promote the hypothesis that the tendency of mice to avoid illumination could be a useful conservation tool, and advance knowledge of risk assessment and foraging under perceived danger.

The neuronal circuitry for pain signals has been intensively studied for decades. The external lateral parabrachial nucleus (PB) was shown to play a crucial role in nociceptive information processing. Previous work, including ours, has demonstrated that stimulating the neuronal pathway from the PB to the central region of the amygdala (CeA) can substitute for an actual pain signal to drive an associative form of threat/fear memory formation. However, it is still unknown whether activation of the PB–CeA pathway can directly drive avoidance behavior, escape behavior, or only acts as strategic freezing behavior for later memory retrieval. To directly address this issue, we have developed a real-time Y-maze conditioning behavioral paradigm to examine avoidance behavior induced by optogenetic stimulation of the PB–CeA pathway. In this current study, we have demonstrated that the PB–CeA pathway carries aversive information that can directly trigger avoidance behavior and thereby serve as an alarm signal to induce adaptive behaviors for later decision-making.

Abstract:The effects of acute and chronic ethanol ingestion on the binding of the inhibitory neurotransmitter 3H‐γ‐aminobutyric acid (GABA) was investigated in inbred strains of mice. Acute effects were analyzed in DBA/2J (alcohol avoiding) and C57BL/6J (alcohol preferring) mice, while chronic effects were analyzed in C57 mice. Acute ethanol (4 g/kg) produced a significant increase in the binding capacity of the low‐affinity γ‐aminobutyric acid binding site in both C57 (12%) and DBA (23%) mice, without significantly altering other binding parameters. The enhanced binding capacity may be responsible for the behavioral depression associated with ethanol use. Chronically treated C57 mice exhibited a decrease in the density of low‐affinity GABA receptor sites. These results suggest the possible involvement of γ‐aminobutyric acid synaptic function in the neuropharmacological effects of ethanol. The possibility that chronic ethanol administration may result in adaptation of γ‐aminobutyric acid receptors to the continuous presence of ethanol‐induced central nervous system depression is discussed.

In order to characterize the effects of septal lesionsupon adrenal stress responses, plasma corticosterone levels were examined 2 days after surgery in normal and sham-operated rats and in rats with septal lesions 0, 5, 15, 30, and 60 min after either 5 sec of handling or 3 min of novel environment at both the crest and trough of the adrenal cycle. Baseline levels and diurnal variations were comparable in lesioned and non-lesioned groups. Non-lesioned rats reacted to stress with an elevation of corticosterone which peaked and leveled off 15 min after the end of stress. Their response was greater following 3 min of novel environment than after 5 sec of handling. 60 min after stress, corticosterone levels had begun to return to baseline levels at trough but not at crest of the adrenal cycle. Rats with a septal lesion had an overall stress-response pattern similar to that observed in non-lesioned animals, but the response latency of septally-lesioned rats was much shorter than that of non-lesioned animals, and their corticosterone levels at 0, 5, and 15 min after stress were greater than those of non-lesioned rats. The mean magnitude of overresponse in rats with septal lesions was greater at trough than at the crest of the cycle. It is concluded that baseline adrenal function is not altered by destruction of the septal nuclei but that septally-lesioned rats have a reduced threshold for adrenal activation which is demonstrated by elevated corticosterone levels during the first 15 min following stimulation and that this increased sensitivity to stimulation is greater at trough than at the crest of the adrenal cycle.

Septal lesions enhance shock avoidance behavior in the rat

OS054. Differential strain sensitivities to ischemia/reperfusion in two mouse models of fetal growth restriction

Septal lesion effects on a two-way avoidance task with one-way avoidance task characteristics: A test of a fear-attenuation hypothesis

Acquisition and retention of avoidance behaviors following septal lesions or scopolamine injections in rats

An analysis of licking microstructure in three strains of mice

Effects of vinburnine on experimental models of learning and memory impairments

Chlordiazepoxide and monoamine oxidase inhibitors on avoidance behaviour in mice