Diabetes affects the expression of GABA and potassium chloride cotransporter in the spinal cord: A study in streptozotocin diabetic rats

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Carla Morgado (Author) FMUP; Filipa Pinto-Ribeiro (Author) Other; Isaura Tavares (Author) FMUP

Journal

Title: Neuroscience Letters

Vol. 438

Pages: 102-106

ISSN: 0304-3940

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 39 Citations

Scopus - 43 Citations

Pubmed / Medline

Scientific classification

FOS: Medical and Health sciences > Other medical sciences

CORDIS: Health sciences > Neuroscience > Neurobiology

Other information

Authenticus ID: P-003-YHW

DOI: 10.1016/j.neulet.2008.04.032

Abstract (EN): Painful diabetic neuropathy is associated to hyperexcitability, and spontaneous hyperactivity of spinal cord neurons. The underlying pathophysiological mechanisms are not clear. Increases in excitartory neurotransmission at the spinal cord, involving glutamate and SP, seem to account for the abnormal neuronal activity, but inhibitory influences were never evaluated. This study aims to analyse the expression of GABA, its synthesizing enzyme glutamic acid decarboxylase (GAD) and the potassium chloride cotransporter (KCC2), in the spinal dorsal horn of streptozotocin (STZ)-induced diabetic rats. Four weeks after saline or STZ (60 mg/kg) injection, animals were sacrificed and the spinal segments L2-L3 were removed and immunoreacted for GABA, GAD and KCC2, or processed for western blotting for KCC2. Densitometric quantification was performed in the superficial dorsal horn (laminae I, II and III) of immunoreacted sections and in the immunoblots. STZ rats presented a significant increase of GABA expression in laminae II and III when compared with control animals, while no differences were detected in GAD expression. A significant decrease in KCC2 expression was detected by immunohistochemistry in laminae I and II, which was confirmed by immunoblotting. Increased GABA levels, along with decrease in KCC2 expression, may underlie the abnormal neuronal activity detected in the spinal cord of diabetic rats. Reduction in KCC2 expression was shown to lead to increases in intracellular chloride concentration and, in such condition, GABA binding to GABA(A) receptor induces membrane depolarization, provoking neuronal excitation rather than inhibition. Based on these findings, we propose that a loss of GABA-mediated inhibitory tone at the spinal cord may result in neuronal hyperexcitability and spontaneous hyperactivity during diabetes.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 5