Improved methods for electroacupuncture and electromyographic recordings in normal and parkinsonian rhesus monkeys

Abstract

Although acupuncture has been widely and routinely used in healthcare in the USA, its use has been based more on empirical observation than on scientific knowledge. Therefore, there is a great need for better understanding the underlying mechanism(s) of action. A great body of evidence supports that nonhuman primates are a candidate for studying human diseases. However, the use of nonhuman primates in neurophysiological, neuroimaging and neurochemical studies is extremely challenging, especially under fully conscious, alert conditions. In the present study, we developed a protocol for safely performing acupuncture, electroacupuncture (EA) and electromyography (EMG) in both normal nonhuman primates and animals with parkinsonian-like symptoms. Four normal and four hemiparkinsonian middle-aged rhesus monkeys were extensively trained, behaviorally monitored, and received both EA and EMG for several months. The results demonstrated that (1) all rhesus monkeys used in the study could be trained for procedures including EA and EMG; (2) all animals tolerated the procedures involving needle/electrode insertion; (3) EA procedures used in the study did not adversely alter the animal's locomotor activities; rather, MPTP-treated animals showed a significant improvement in movement speed; and (4) EMG detected significant differences in muscle activity between the arms with and without MPTP-induced rigidity. Our results support that rhesus monkeys can be used as an experimental animal model to study EA and that EMG has the potential to be used to objectively assess the effects of antiparkinsonian therapies. The results also indicate that animals, especially those with parkinsonian-like symptoms, could benefit from long-term EA stimulations.

Figure 1

Custom acrylic restraint chair. The newly designed vertical chair was used to hold the animals during EA and EMG sessions. As seen in panel A, it has an overall width of 25 cm, height of 69 cm and depth of 28 cm. A rhesus macaque comfortably sitting in the restraint chair is shown in panel B. A collar, inserted into the collar track, is used to safely anchor the animal in the chair. This chair is designed with arm restraints to prevent unnecessary movement with a tray table to serve food items to the animal, and rods for sitting and foot rest, which can be adjusted based on the size of each individual animal, to provide added comfort while sitting in the chair during a training or treatment session. A tray to catch excretion is placed in the bottom of the chair to ensure the utmost comfort for the animal.

Figure 2

Insertion of acupuncture needles. Panel A shows an sterile acupuncture needle being inserted in the acupoint of ZUSANLI (ST36) of a rhesus macaque. Panel B shows the ZUSANLI (ST36) acupoint being stimulated with an acupuncture needle in the same animal. The image in panel B was modified from http://www.itmonline.org/arts/zusanli.htm.

Figure 3

EthoVision analysis of locomotor activity for normal and MPTP-lesioned animals from pre-recorded DVDs. No differences in distance traveled inside the video-cage were found in both normal and MPTP-lesioned animals between pre- and post EA treatment (panel A) during the 60-min recording period. In contrast, a greater than 3-fold increase in movement speed was seen in the MPTP-lesioned animals but not in normal animals (panel B). The movement speed of the animals with parkinsonian-like symptoms measured post EA was virtually the same as that of normal animals. *P ≤ 0.05; pre vs. post EA in MPTP-treated animals.

Figure 4

EMG spectra analysis for normal and MPTP-lesioned rhesus macaques. No differences in EMG were seen in the four normal animals between the right and left upper limbs (panel A). For the MPTP-lesioned animals, the data indicates that movements on the MPTP-lesioned side (left) were significantly slower and required more muscle activity (panel B). Apomorphine (0.15mg/kg) administration significantly improved upper limb rigidity on the MPTP-affected side of the body in all four hemiparkinsonian animals (panel C). *P ≤ 0.05; MPTP-lesioned (left side) versus unlesioned (right side).

Figure 5

EMG studies in MPTP-treated monkeys. As seen in panel A, the electrodes were attached to the animal’s biceps brachia on both the left and right arms. A representative comparison of EMG spectra between the MPTP-lesioned (panel B) and unlesioned (panel C) sides of one hemiparkinsonian animal is shown pre- and post-apomorphine (APO) administration. As seen in panel B, the pattern of EMG on the MPTP-lesioned side (lower left panel in Panel B) was virtually identical to that seen on the MPTP-unlesioned side (lower right panel in Panel C) after apomorphine (0.15mg/kg) administration.