Activating Striatal Parvalbumin Interneurons to Alleviate Chemotherapy-Induced Muscle Atrophy

Abstract

Background: Cisplatin is a widely used chemotherapeutic agent for treating solid tumours. Still, it induces severe side effects, including muscle atrophy. Understanding the mechanisms of cisplatin-induced muscle loss and exploring potential therapeutic strategies are essential. Parvalbumin (PV) interneurons in the striatum play a crucial role in motor control, and recent studies suggest that their activation may alleviate motor deficits. This study investigates the effects of chemogenetic activation of PV interneurons on cisplatin-induced muscle atrophy and motor dysfunction in mice.

Methods: Wild-type C57BL/6 mice and transgenic hM3Dq mice were used in this study. Cisplatin (3 mg/kg) was administered intraperitoneally for 7 days to induce muscle atrophy. Mice were then treated with clozapine-n-oxide (CNO) to activate PV interneurons. Muscle strength and endurance were assessed using grip strength measurements, the inverted grid test and the wire hang test. Neuromuscular junction (NMJ) integrity was examined via histological analysis. Exercise intervention was also included, using a treadmill with a 15° incline for 60 min at varying speeds during seven consecutively days.

Results: Cisplatin treatment significantly reduced body weight (p < 0.001), grip strength (forelimb strength: p < 0.001, four-limb strength: p < 0.001), endurance (inverted grid test: p = 0.047, wire hang test: p = 0.014) and NMJ integrity (partially innervated NMJs: p = 0.0383). PV interneuron activation with CNO improved spontaneous motor activity in cisplatin-treated mice, as evidenced by a significant increase in total travel distance (p = 0.049) in the open-field test. Histological analysis showed a reduced ratio of partially innervated NMJs in the PV-cre group compared to the control virus group (p = 0.0441). Muscle strength also improved significantly, with forelimb grip strength increased (p < 0.001) and four-limb grip strength increased (p = 0.018). Muscle wet-weight ratios were significantly higher in the PV-cre group (quadriceps: p = 0.030). Exercise intervention significantly improved grip strength (forelimb: p < 0.001, four-limb: p = 0.002), muscle endurance (four-limb hang test: p = 0.048) and muscle weight (quadriceps: p = 0.015, gastrocnemius: p = 0.022), with an increase in muscle fibre cross-sectional area (p = 0.0018).

Conclusion: Activation of PV interneurons significantly alleviates cisplatin-induced motor deficits and muscle atrophy by improving spontaneous motor activity, NMJ integrity and muscle function. It has a similar effect to short-term exercise and may offer a promising therapeutic strategy for mitigating chemotherapy-induced muscle atrophy.

Keywords: cisplatin; muscle atrophy; parvalbumin interneurons; striatum.

FIGURE 1

Effects of cisplatin on muscle atrophy. (a) Reduced body weight ratio (measured weight/initial weight) following cisplatin treatment. (b) Forelimb strength and (c) hindlimb strength were assessed using a grip strength meter, measured in grams before and after cisplatin injection. (d) The forelimb function and (e) hindlimb function were evaluated by measuring the forelimb hang time in seconds before and post‐injection. Data are presented as Mean ± SEM (n = 6). CON: control group; CIS: cisplatin‐treated group.

FIGURE 2

Impact of striatal PV neuron intervention on motor and emotional states in cisplatin‐treated mice. (a) Movement trajectories following activation of striatal PV interneurons. (b) Spontaneous motor activity is quantified by total travel distance (cm) within a fixed period. (c) Representative images of NMJs in the TA muscle. The muscle fibres were stained whole mount with α‐BTX (red) to label AChR clusters and NF/synapsin‐1 (green) to label nerve terminals. Scale bar, 50 μm. (d) Quantification of NMJs in (c), including the ratio of fragmented receptors, partially innervated NMJs and denervated NMJs in each 20 × field. CONV group, n = 105 NMJs from three mice; PV‐cre group, n = 135 NMJs from three mice. Data are presented as Mean ± SEM (n = 6). CONV: control virus injection; PV‐cre: PV‐cre virus injection.

FIGURE 3

Chemogenetic activation of striatal PV interneurons on cisplatin‐induced muscle atrophy in vivo. (a) Schematic of the striatal interneuron intervention protocol. (b) Body weight ratio (measured weight/ initial weight) following chemogenetic activation in cisplatin‐treated mice. (c) Forelimb grip strength and (d) hindlimb grip strength were assessed before and 7 days after chemogentic activation. (e) Forelimb function and (f) hindlimb function evaluated by forelimb hang time. Data are presented as Mean ± SEM (n = 6). CONV: control virus injection; PV‐cre: PV‐cre virus injection.

FIGURE 4

Changes in muscle mass and muscle fibre cross‐sectional area in cisplatin‐injected mice after chemogenetic activation. (a) Representative images of muscles from each group. (b–d) Muscle weight of the quadriceps (b), gastrocnemius (c) and tibialis anterior (d) were normalized to body weight. (e) Representative HE‐stained images of the quadriceps muscle (scale bar: 100 μm). (f) The cross‐sectional area of quadriceps muscle fibres was quantified using ImageJ software. Data are presented as Mean ± SEM (n = 4). CONV: control virus injection; PV‐cre: PVcre virus injection.

FIGURE 5

Effects of exercise on cisplatin‐induced muscle atrophy in vivo. (a) Schematic of the treadmill exercise intervention protocol. (b) Body weight ratio (measured weight/ initial weight) following exercise intervention in cisplatin‐treated mice. (c) Forelimb grip strength and (d) hindlimb grip strength assessed before and 7 days after exercise intervention. (e) Forelimb function and (f) hindlimb function were assessed by forelimb hang time. Data are presented as Mean ± SEM (n = 6). CISC: cisplatin‐treated sedentary control group; CISE: cisplatin‐treated exercise intervention group.

FIGURE 6

Effects of short‐term exercise on muscle mass and muscle fibre cross‐sectional area in cisplatin‐injected mice. (a) Representative images of muscles from each group. (b–d) Muscle weights of the quadriceps (b), gastrocnemius (c) and tibialis anterior (d) muscles normalized to body weight. (e) Representative HE‐stained images of the quadriceps muscle (scale bar: 100 μm). (f) The cross‐sectional area of quadriceps muscle fibres was quantified using ImageJ software. Data are presented as Mean ± SEM (n = 5, a). CISC: cisplatin‐treated sedentary control group; CISE: cisplatin‐treated exercise intervention group.