trpv1 cre mice  (Jackson Laboratory)

Journal: bioRxiv

Article Title: Discrete and sequential critical periods organise the development of task-specific sensorimotor circuits in mice

doi: 10.1101/2025.09.18.676788

Figure Lengend Snippet: Three sequential windows of sensorimotor plasticity revealed by behaviour and anatomy. (a) Average brush response to five consecutive brush strokes across postnatal development. A significant increase in dynamic tactile sensitivity is observed between the second and third postnatal weeks, indicating that reflexive responses to brush stimulation mature by the end of the second postnatal week (RM one-way ANOVA, P < 0.01; Tukey’s test: P8 vs.. P15, P20 * P < 0.05; P9 vs.. P14, P15, P20 § P < 0.05; P11 vs.. P14 & P < 0.05; n = 6). Coloured bars indicate putative developmental windows of plasticity as defined by behaviour and anatomical markers in b-d: blue, neonatal (P8-12); green, juvenile (P13-17); purple, adolescent (P18-22); grey, adult. (b) Representative spinal cord sections immunostained for myelinated afferents (vGluT1 + , cyan) at P9 (top), P13 (middle), and P18 (bottom). (c) Representative spinal sections immunostained for unmyelinated afferents (IB4 + , yellow) at the same ages. (d) Representative spinal sections following retrograde mCherry tracing from the somatosensory cortex (magenta), showing progressive targeting of corticospinal input to superficial and deep dorsal horn over postnatal development. These data reveal three developmental windows of central afferent maturation. (e) Schematic of the viral transfection strategy: TRPV1 + fibres were selectively targeted by intraplantar injection of a Cre-inducible AAV9-hM3Dq-mCherry vector in P0 TRPV1 Cre pups. (f) Representative images showing hM3Dq-mCherry expression in ipsilateral L4 dorsal root ganglia (DRG) and spinal dorsal horn at (top to bottom) 8, 13, and 18 days post-injection. (g) Quantification of mCherry-labelled DRG soma diameters at each developmental stage (L4-L6; n = 3 per age). (h) Representative section of DRG co-labelled with mCherry (red) and CGRP (green), with quantification of overlap (L4-L6; n = 3 per age). Scale bars: 200 μm (dorsal horn), 200 μm (DRG).

Article Snippet: Male and female TRPV1 Cre mice (B6.129-Trpv1tm1(cre)Bbm/J, stock #017769, Jackson Laboratory) were used for all remaining experiments.

Techniques: Transfection, Injection, Plasmid Preparation, Expressing

Journal: bioRxiv

Article Title: Discrete and sequential critical periods organise the development of task-specific sensorimotor circuits in mice

doi: 10.1101/2025.09.18.676788

Figure Lengend Snippet: Lasting dynamic touch sensitivity after chronic primary afferent activation in the neonatal period. (a) Schematic (top) of the dynamic brush and static von Frey hair assays, with representative stills (bottom) showing withdrawal responses scored 1-4. (b) Average withdrawal to five consecutive dynamic brush strokes significantly increased in adults with neonatal primary afferent activation (left; P8-12; ctrl vs. hM3Dq, * P < 0.05, unpaired t-test), but unchanged in juvenile (middle; P13-17) and adolescent (right; P18-22) groups (both n . s ., Mann-Whitney test and unpaired t-test, respectively). (c) Trial-by-trial analysis revealed no differences across individual brush strokes (all n . s ., RM two-way ANOVA). (d) Static touch sensitivity (von Frey hair thresholds) was unchanged in all groups (all n . s ., unpaired t-tests). Group sizes: neonatal, n = 7 ctrl, 8 hM3Dq; juvenile, n = 6 ctrl, 9 hM3Dq; adolescent, n = 7 ctrl, 11 hM3Dq. TRPV1 Cre mice expressing hM3Dq are shown in blue (neonatal), green (juvenile), and purple (adolescent); controls are shown in grey. All testing was performed in adulthood following transient developmental primary afferent activation.

Article Snippet: Male and female TRPV1 Cre mice (B6.129-Trpv1tm1(cre)Bbm/J, stock #017769, Jackson Laboratory) were used for all remaining experiments.

Techniques: Activation Assay, MANN-WHITNEY, Expressing

Journal: bioRxiv

Article Title: Discrete and sequential critical periods organise the development of task-specific sensorimotor circuits in mice

doi: 10.1101/2025.09.18.676788

Figure Lengend Snippet: Lasting heat-evoked nocifensive behaviour after chronic primary afferent activation the juvenile period. (a) Schematic of heat-induced escape behavioural assay. (b) Quantification of average heat-induced escape behaviour. Adult mice that had received neonatal (left; P8-12), juvenile (middle; P13-17), or adolescent (right; P18-22) afferent activation showed no differences in escape behaviour (all n . s ., unpaired t-tests). (c) Schematic of thermal nocifensive behavioural assay. (d) Quantification of average heat-induced aversive behaviour. Adults with juvenile afferent activation displayed reduced heat aversive behaviours (middle; ctrl vs. hM3Dq, * P < 0.05, unpaired t-test), with no significant effect in neonatal (left) or adolescent (right) groups (all n . s ., Mann-Whitney tests. (e) Schematic of Pin Prick behavioural assay. (f) Quantification of pin prick response. Average withdrawal magnitude to noxious pin prick was unchanged across groups (all n . s ., unpaired t-test or Mann-Whitney test). (g) Response to repeated pin pricks was equally unchanged (all n . s ., RM two-way ANOVA), although neonatally treated mice failed to adapt to repeated stimuli (left; Pin Prick event: F 1.638, 21.30 = 10.37, P < 0.01). Group sizes: neonatal, n = 7 ctrl, 8 hM3Dq; juvenile, n = 6 ctrl, 9 hM3Dq; adolescent, n = 7 ctrl, 11 hM3Dq. TRPV1 Cre mice expressing hM3Dq are shown in blue (neonatal), green (juvenile), and purple (adolescent); controls are shown in grey. All testing was conducted in adulthood following transient developmental primary afferent activation.

Article Snippet: Male and female TRPV1 Cre mice (B6.129-Trpv1tm1(cre)Bbm/J, stock #017769, Jackson Laboratory) were used for all remaining experiments.

Techniques: Activation Assay, MANN-WHITNEY, Expressing

Journal: bioRxiv

Article Title: Discrete and sequential critical periods organise the development of task-specific sensorimotor circuits in mice

doi: 10.1101/2025.09.18.676788

Figure Lengend Snippet: Lasting gross motor coordination deficits after chronic primary afferent activation in the juvenile period. (a) Schematic of CatWalk behavioural assay. (a-b) Representative CatWalk step pattern sequences from adults following neonatal (left; P8-12), juvenile (middle; P13-17), or adolescent (right; P18-22) afferent activation. Solid bars represent stance phase. RH: right hindlimb; RF: right forelimb; LF: left forelimb; LH: left hindlimb. (c) Schematic of hind paw in stance phase. (d) Quantification of stance phase duration across three runs. Average stance phase duration was significantly increased in the ipsilateral hind paw of the juvenile group (middle; F 1,46 = 9.468, P < 0.05; Šídák’s test * P < 0.05), but unchanged in neonatal (left) or adolescent (right) groups (both n . s ., two-way ANOVA). (e) Schematic of hind paw in swing phase. (f) Quantification of swing phase duration across three runs. Swing phase duration was similarly altered only in the juvenile group (middle; F 1,46 = 4.741, P < 0.05), with no changes in neonatal (left) or adolescent (right) groups (both n . s ., two-way ANOVA). (g) Schematic of initial dual stance duration. (h) Quantification of initial dual stance duration across three runs. Initial stance was selectively increased in the juvenile group (middle; F 1,46 = 4.258, P < 0.05) but unaffected in neonatal (left) or adolescent (right) groups (both n . s ., two-way ANOVA). (i) Schematic of run duration. (j) Quantification of run duration across three runs. Average run duration was unchanged across all groups (all n . s . unpaired t-tests). Group sizes: neonatal, n= 7 ctrl, 8 hM3Dq; juvenile, n = 6 ctrl, 9 hM3Dq; adolescent, n = 7 ctrl, 11 hM3Dq. TRPV1 Cre mice expressing hM3Dq are shown in blue (neonatal), green (juvenile), and purple (adolescent); controls are shown in grey. All testing was conducted in adulthood following transient developmental primary afferent activation. Grey shaded areas indicate values contralateral hindlimb values.

Article Snippet: Male and female TRPV1 Cre mice (B6.129-Trpv1tm1(cre)Bbm/J, stock #017769, Jackson Laboratory) were used for all remaining experiments.

Techniques: Activation Assay, Expressing

Journal: bioRxiv

Article Title: Discrete and sequential critical periods organise the development of task-specific sensorimotor circuits in mice

doi: 10.1101/2025.09.18.676788

Figure Lengend Snippet: Lasting skilled locomotor impairments after adolescent afferent activation. (a) Schematic of beamwalk behavioural assay. (b) Representative stick figure diagrams showing three complete hindlimb step cycles (swing and stance) for adults following neonatal (left; P8-12), juvenile (middle; P13-17), or adolescent (right; P18-22) afferent activation. Arrows point to loss of swing phase fluidity during stepping. (c) Schematic of knee-ankle-paw (KAP) angle. (d) Spider plot of KAP angle over three consecutive steps. KAP angle was altered only in the adolescent group (right; F 1,60 = 7.790, P = 0.01; interaction F 3,60 = 3.210, P = 0.05), with reductions concentrated between 50-70° (Šídák’s test, * P < 0.05). (e) Schematic of hip-knee-ankle (HKA) angle. (f) Spider plot of HKA angle over three consecutive steps. HKA angle was significantly reduced in the adolescent group (right; F 1,75 = 5.054, P < 0.05; interaction F 4,75 = 2.613, P < 0.05), with post hoc analysis showing a selective decrease in the 100-120° range (Šídák’s test, ** P < 0.01). No significant changes were observed in neonatal (left) or juvenile (middle) groups (all n . s ., two-way ANOVA). Group sizes: neonatal, n = 7 ctrl, 8 hM3Dq; juvenile, n = 6 ctrl, 9 hM3Dq; adolescent, n = 7 ctrl, 11 hM3Dq. TRPV1 Cre mice expressing hM3Dq are shown in blue (neonatal), green (juvenile), and purple (adolescent); controls are shown in grey. All testing was conducted in adulthood following transient developmental activation.

Article Snippet: Male and female TRPV1 Cre mice (B6.129-Trpv1tm1(cre)Bbm/J, stock #017769, Jackson Laboratory) were used for all remaining experiments.

Techniques: Activation Assay, Expressing

Journal: bioRxiv

Article Title: Discrete and sequential critical periods organise the development of task-specific sensorimotor circuits in mice

doi: 10.1101/2025.09.18.676788

Figure Lengend Snippet: Adult dorsal horn neuronal responses and interneuron populations following early-life afferent manipulation. (a) Schematic of Neuropixels probe insertion into the medial dorsal horn, with confocal image of the ipsilateral hemisection showing DiI stain from the probe track and DAPI counterstain for grey matter visualization. (b) Example spinal MUA response to five consecutive brush stimulations of the ipsilateral hind paw, shown as raster plot (left) and peri-stimulus time histogram (right; PSTH). (c-d) Violin plots showing mean z-scores (0-1 s post-stimulus window) of MUA recorded across probe depth bins (0-100 μm, 100-200 μm, 200-300 μm, 300-400 μm, 400-500 μm) in neonatal (c; P8-12) and juvenile (d; P13-17) groups. No significant differences were observed between control and hM3Dq mice in either group (all n . s ., Mann-Whitney tests). (e-h) Representative images of PV (cyan) and PKCγ (magenta) expression in the ipsilateral dorsal horn of neonatal and juvenile groups. (i) Schematic of localisation of spinal lamina II PV + interneurons used for quantification. (j) Quantification of PV + interneurons in lamina II. PV + interneuron counts were significantly reduced in lamina II of neonatally stimulated mice (left; P < 0.05, unpaired t-test) but not in juvenile groups (right; n . s ., Mann-Whitney tests). (k) Schematic of localisation of spinal lamina II PKCγ + interneurons used for quantification. (l) Quantification of PKCγ + interneurons in lamina II. PKCγ + interneuronal counts were unchanged by early life afferent input (all n . s ., Mann-Whitney tests). Group sizes: neonatal, n = 7-10 ctrl, 7-9 hM3Dq; juvenile, n = 5-8 ctrl, 3-4 hM3Dq. TRPV1 Cre mice expressing hM3Dq are shown in blue (neonatal) and green (juvenile); controls are shown in grey. All extracellular recordings and immunohistochemical analyses were conducted in adulthood following transient developmental primary afferent activation. Scale bar: 200 μm.

Article Snippet: Male and female TRPV1 Cre mice (B6.129-Trpv1tm1(cre)Bbm/J, stock #017769, Jackson Laboratory) were used for all remaining experiments.

Techniques: Staining, Control, MANN-WHITNEY, Expressing, Immunohistochemical staining, Activation Assay