Different effect of locomotor exercise on the homogenate concentration of amino acids and monoamines in the rostral and caudal lumbar segments of the spinal cord in the rat

Abstract

Study design: The effect of long-term (4 weeks) moderate locomotor exercise on segmental distribution of glutamate (Glu), aspartate, gamma-aminobutyric acid, glycine (Gly), serotonin and noradrenaline in the spinal cord of adult rats was investigated. Objectives: In light of the data showing modulation of some neurotransmitters in the lowlumbar segments of the rat due to physical exercise, our aim was to establish how segmentally specific is this effect with respect to neuroactive amino acids and monoamines. Setting: Laboratory of Reinnervation Processes, Department of Neurophysiology, Nencki Institute of Experimental Biology, Warsaw, Poland. Methods: Amino acids and monoamines content was measured by means of HPLC in the whole tissue homogenate of the spinal cord in nonexercised and exercised rats. Results: Glu and Gly homogenate concentration was the highest among all tested compounds. There was an intersegmental rostro-caudal gradient of concentration of neuroactive amino acids and monoamines, progressing caudally. Exercise modified this gradient exerting opposite effect on their concentration of amino acids and monoamines in the rostral and caudal lumbar segments. Conclusion: Locomotor exercise leads to neurochemical remodeling of the spinal cord, which is differently manifested in the rostral and caudal lumbar segments of the spinal cord.

Overexpression of BDNF Increases Excitability of the Lumbar Spinal Network and Leads to Robust Early Locomotor Recovery in Completely Spinalized Rats

“…Tissue extraction and HPLC were performed as described by Skup and co-authors [47]. Briefly, 5 weeks after transection, the rats were decapitated, immediately after that the corps were cooled with dry ice, and spinal cords were removed from the vertebral columns and divided into mid- and caudal thoracic (Th), rostral lumbar (L1–2) and caudal lumbar (L3–5) segments.…”

“…We took into account the functional and biochemical differences among lumbar segments in the adult rat, where greater capacity to induce the locomotor pattern is attributed to the rostral (L1–2) than to the caudal lumbar segments (L3–6), where the motoneurons innervating the majority of hindlimb muscles are located (for review see [44]–[47]). …”

Adaptations in Glutamate and Glycine Content within the Lumbar Spinal Cord Are Associated with the Generation of Novel Gait Patterns in Rats following Neonatal Spinal Cord Transection

“…Assuming glutamate receptor expression was unchanged after spinal cord transection (Krenz and Weaver, 1998), the abnormally-high levels of glutamate were consistent with the development of an enhanced glutamatergic drive. It is interesting to note that in intact rats, treadmill training did not raise HPLC-measured glutamate levels in the lumbar spinal cord (Skup et al, 2007). Thus it appeared that spinally transected animals primarily relied on glutamatergic excitation to drive the CPG whereas normal animals utilized pathways involving multiple neurotransmitter systems.…”

“…For the Trained rats, the terminal experiment occurred within 2 hours after the completion of the last training (Skup et al, 2007). This time frame was chosen to avoid acute effects due to training on amino acid levels (Walwyn et al, 1999).…”

“…We used high-performance liquid chromatography (HPLC) to analyze glutamate and glycine levels within the lumbar spinal cord. HPLC provides a sensitive measurement of the concentration of neurochemicals within nervous tissue and has been used to measure exercise-induced changes in glutamate and glycine levels in the lumbar spinal cord of intact rats (Skup et al, 2007). We also performed immunohistochemical analyses of the glutamate and glycine vesicular transporters, VGLUT1 and GLYT2.…”