modular standard mouse operant chambers  (Med Associates Inc)

Journal: iScience

Article Title: Melanocortin 4 receptor-expressing neurons in the lateral stripe of the striatum regulate affect and motor control

doi: 10.1016/j.isci.2025.112456

Figure Lengend Snippet: MC4R-LSS neurons are activated by aversive foot shocks in a D1-independent manner (A) Timeline of experiments. (B) Representative picture of GCaMP8m-expression and fiber placement in the lateral stripe of the striatum (LSS) of an MC4R-cre mouse. Fiber tract and anterior commissure (aca) marked with dashed line; LSS marked with arrow. LV, lateral ventricle. Scale bar 200 μm. (C) GCaMP8m signal measured with fiber photometry from MC4R-LSS neurons shows activation of MC4R-LSS neurons in response to aversive shocks, but not to the onset of the predictive tone cue. No change in neural activity was seen in response to shock omission in the fear test on day 2. Mean and SEM from 6 mice, 6 trials per mouse. (D) Heatmap of the data shown in (C) but split out per trial showing that the neural response is similar across all trials. Each row in the heatmap represents the mean from 6 mice. (E) Dopamine measurements from the LSS during the same behavioral paradigm as in (C). Dopamine is released in the LSS in response to both the aversive foot shocks and their predictive tone cues. No clear change in dopamine release was seen in response to shock omission in the fear test on day 2. Mean and SEM from 7 mice, 6 trials per mouse. (F) Heatmap of the data shown in (E) but split out per trial showing that the tone-induced dopamine release develops during the session. Each row in the heatmap represents the mean from 7 mice. (G) iGluSnFR-measurements of glutamate release onto D1-expressing neurons in the LSS during fear conditioning. Glutamate is released onto D1-expressing neurons in response to the aversive foot shock. A small release can be seen in response to the tone onset. Mean and SEM from 10 mice, 6 trials per mouse. (H) Heatmap of the data shown in (G), but split out per trial, showing that the shock-induced glutamate release is similar across trials and that the tone-induced release is developed within the session. Each row in the heatmap represents the mean from 10 mice. (I) Timeline of the crossover experiment testing if shock-induced activity of MC4R-LSS neurons is D1-dependent. (J) Group mean peri-event traces (± SEM) from the experiment shows a robust increase in neural activity in response to the foot shock after both saline-injection and pretreatment with the D1-antagonist SCH23390 (0.2 mg/kg; n = 7). (K) Mean peak size during the shock for each animal showing that SCH23390 does not affect the shock-induced neural response ( n = 7, paired two-tailed t-test). (L) Analysis of the inactivity time during the sessions showing that mice spend significantly more time inactive after SCH23390 injection compared to saline injection ( n = 11, paired two-tailed t-test). ∗∗∗ p < 0.001.

Article Snippet: Standard mouse operant conditioning chamber , Med Associates , ENV-307W.

Techniques: Expressing, Activation Assay, Activity Assay, Saline, Injection, Two Tailed Test

Journal: bioRxiv

Article Title: Chemogenetic activation of corticotropin-releasing factor-expressing neurons in the anterior bed nucleus of the stria terminalis reduces effortful motivation behaviors

doi: 10.1101/2023.02.23.529717

Figure Lengend Snippet: Chemogenetic activation of CRF+ BNST neurons decreased lever pressing for sucrose pellets in high-performing males. ( A ) 6–7-week-old CRF-ires-Cre transgenic mice were bilaterally injected with Cre-dependent Gq-DREADD or a control Cre-dependent mCherry virus. After recovery, mice were fasted and trained in operant chambers to lever press for sucrose pellets. Over 10 days, a progressive ratio (PR) baseline frequency of lever pressing was collected, wherein mice were trained to lever press at increasing frequencies in an (FR(n+1) x 15) PR reinforcement schedule. During PR/concurrent chow (CHOW) baseline training, concurrently available lab chow was freely available on the chamber floor. Mice were then refed and allowed ad libitum access to lab chow for 20 hours, and sucrose pellets for 4 hours, prior to an outcome devaluation trial. During 4 days of PR/CHOW testing, mice were injected with alternating treatments of CNO or Vehicle 30 minutes prior to PR/CHOW testing, to assess how chemogenetic activation of CRF+ BNST neurons alters lever pressing in the PR/CHOW task. Appetite was assessed over two days of free feed testing, wherein mice were injected with alternating treatments of CNO or Vehicle. During open field and sucrose preference testing, all mice were injected with CNO solution. Mice were fasted to 85-90% of their ad libitum body weights throughout training and testing, except where marked with a chow icon, which represents free access to standard lab chow. Arrows represent daily CNO or Vehicle injections, 30 minutes prior to testing. ( B ) Males (grey) lever pressed significantly more frequently than females (black) during PR baseline training ( p < 0.05) on days 2, 4, 5, 7, 8 ( p < 0.05), and 10 ( p < 0.01). ( C ) Males also pressed more than females during PR/CHOW ( p < 0.001) baseline training, including days 1 ( p < 0.05), 2 ( p < 0.001), and 3-5 ( p < 0.01). ( D ) Males lever pressed significantly less when re-fed during outcome devaluation, compared to PR ( p < 0.001) or PR/CHOW ( p < 0.0001) baseline. Female lever pressing did not significantly decline during outcome devaluation. ( E ) Mice were designated high performers if their average PR/CHOW baseline lever pressing was greater than the median lever pressing (perforated line) for all mice. All high-performing mice were males (gray points), but all females (black points) were at or below the median baseline frequency. ( F ) In the PR/Chow test, high-performing Gq-DREADD males, when injected with CNO, lever pressed less than when injected with Vehicle ( p < 0.05). No effect of CNO was observed in mCherry control mice ( p = 0.884). Values are plotted as individual values and mean +/- SEM. * p < 0.05; *** p < 0.001.

Article Snippet: Standard mouse operant chambers (Med Associates, Fairfax, VT) were housed in sound-attenuating cubicles inside a behavioral testing room.

Techniques: Activation Assay, Transgenic Assay, Injection