Bioelectric Activity of the Spinal Cord Interneurons in Experimental Menopause in Female Rats

Background/Aims: Current therapies for spinal cord injury (SCI) have limited efficacy, and identifying a therapeutic target is a pressing need. Sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2 (SERCA2) plays an important role in regulating calcium homeostasis, which has been shown to inhibit apoptosis. Exendin-4 has been shown to inhibit the apoptosis of nerve cells in SCI, which can also improve SERCA2 expression. In this study, we sought to determine whether exendin-4 plays a protective role in a rat model of SCI via SERCA2. Methods: To investigate the effects of exendin-4 on SCI, a rat model of SCI was induced by a modified version of Allen’s method. Spinal cord tissue sections from rats and western blot analysis were used to examine SERCA2 expression after treatment with the long-acting glucagon-like peptide 1 receptor exendin-4 or the SERCA2 antagonist 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CE). Locomotor function was evaluated using the Basso Beattie Bresnahan locomotor rating scale and slanting board test. Results: Cell apoptosis was increased with CE treatment and decreased with exendin-4 treatment. Upregulation of SERCA2 in female rats with SCI resulted in an improvement of motor function scores and histological changes. Conclusion: These findings suggest that exendin-4 plays a protective role in a rat model of SCI through SERCA2 via inhibition of apoptosis. Existing drugs targeting SERCA2 may be an effective therapeutic strategy for the treatment of SCI.

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Activation of the external urethral sphincter central pattern generator by a 5-HT1A receptor agonist in rats with chronic spinal cord injury

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00142.2006 ◽

2007 ◽

Vol 292 (4) ◽

pp. R1699-R1706 ◽

Cited By ~ 42

Author(s):

Paul C. Dolber ◽

Baojun Gu ◽

Xiaoyang Zhang ◽

Matthew O. Fraser ◽

Karl B. Thor ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Receptor Agonist ◽

Bladder Capacity ◽

Female Rats ◽

Residual Volume ◽

Urethral Sphincter ◽

External Urethral Sphincter ◽

Chronic Spinal Cord Injury ◽

Cord Injury

We recently demonstrated that treatment with the 5-HT1A/7 receptor agonist [(R)-(+)-8-hydroxy-2-di-n-propylamino]tetralin (8-OH-DPAT) increases bladder capacity in chloralose-anesthetized female cats with chronic spinal cord injury. In the current study, we investigated the effects of 8-OH-DPAT on bladder capacity and external urethral sphincter (EUS) activity in urethane-anesthetized female rats (initial body mass 175–200 g) with chronic spinal cord injury (transsection at T10). Cystometric study took place 8–12 wk posttranssection. Intravesical pressure was monitored in urethane-anesthetized rats with a transvesical catheter, and EUS activity was assessed electromyographically. Spinal cord injury disrupts phasic activity of the EUS, resulting in decreased voiding efficiency and increased residual volume. 8-OH-DPAT induced a dose-dependent decrease in bladder capacity (the opposite of its effect in chronic spinal cord-injured cats) with an increase in micturition volume and decrease in residual volume resulting from improvement in voiding efficiency. The unexpected improvement in voiding efficiency can be explained by the 8-OH-DPAT-induced emergence of phasic EUS relaxation. Phasic EUS relaxation was also altered by 8-OH-DPAT in spinally intact rats, whereas the 5-HT1A receptor antagonist N-tert-butyl-3-[4-(2-methoxyphenyl)-piperazin-1-yl]-2-phenylpropanamide (WAY-100635), on its own, was without effect. It remains to be determined when phasic relaxation is restored after spinal cord injury, and indeed whether it is ever truly lost or is only temporarily separated from excitatory input.

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