Group III mGluRs Modulate Defensive and Anxiety-Like Behaviors in Juvenile Zebrafish

IUPS2025, Frankfurt, Almanya, 11 - 14 Eylül 2025, (Yayınlanmadı)

Aim

This study investigates the role of group III metabotropic glutamate receptors (mGluRs) in regulating

anxiety-like and defensive behaviors in juvenile zebrafish, with a focus on the habenula—a key brain

region involved in sensory processing and behavioral modulation.

Methods & Results

To assess how these receptors influence behavior, we used ventricular injections of the mGluR antagonist

CPPG and evaluated changes using the Light-Dark Stimulation (LDS) assay in the Zantiks MWP system. At

21 days post-fertilization (dpf), HuC:GCaMP6s zebrafish were assigned to one of three groups: untreated

controls (n=17), vehicle controls (NaOH; n=18), and CPPG-injected fish (n=16). Following treatment, fish

were placed in six-well plates for a 2.5-hour LDS protocol, beginning with a 15-minute baseline to assess

acclimation. CPPG-injected fish showed significantly increased thigmotaxis during this phase (p<0.05),

indicating elevated anxiety in the novel environment. Throughout LDS testing, the CPPG group exhibited

heightened responses to both light-off and light-on transitions, with a marked increase in burst swimming

activity, measured as average distance traveled, compared to both control groups.

Conclusions

These results suggest that blocking group III mGluRs impairs habenular sensory gating, leading to

exaggerated behavioral responses to environmental changes. Overall, our findings underscore the

importance of glutamatergic signaling through group III mGluRs in the habenula for maintaining behavioral

stability and adaptive responses. This work contributes to a broader understanding of how mGluRmediated

pathways influence vertebrate neural circuit function and stress-related behavior.