Changes in BDNF Protein Levels during Inflammation Induced by Carrageenan in Male Rat

Several studies have described the effects of brain-derived neurotrophic factor (BDNF) during tissue injury or inflammation. BDNF expression levels in the nervous system are altered in a number of pain models including peripheral inflammation، injury and neuropathic pain paradigms. Immune cell are considered as the source of circulating BDNF. Opioid receptors participate in the function of immune cells. The aim of this study was to investigate the alteration of BDNF during carrageenan-induced inflammation and morphine anti-inflammatory effects.

Inflammation was induced by 0. 05 ml of 3% W/V solution of lambda carrageenan in saline injected into the plantar surface of the right hind paw. Edema of the injected paw was measured during the 6 h period after the carrageenan injection. Moreover، to assess the anti-inflammatory effect of morphine، morphine hydrochloride (7mg/kg) was injected 30 minutes prior to the carrageenan. BDNF levels in serum were determined by ELISA.

Four hours after the injection of carrageenan، the volume of the paw was significantly higher than the non-inflamed paw. Pretreatment with morphine، produced a significant decrease in the carrageenan-induced swelling. Naloxone evoked development of the carrageenan inflammation at 2 hours. Administration of carrageenan elicited a significant increase in BDNF serum levels.

It seems that the inflammatory effects of the carrageenan are mediated in part by BDNF. Such association is not attributable to the anti-inflammatory effects of morphine.