TY - JOUR
T1 - Opioid receptor activation
T2 - Suppression of ischemia/reperfusion-induced production of TNF-α in the retina
AU - Husain, Shahid
AU - Liou, Gregory I
AU - Crosson, Craig E.
PY - 2011/4
Y1 - 2011/4
N2 - PURPOSE. The detrimental role of TNF-α in ischemia-induced tissue damage is known. The authors study examined whether opioid receptor activation alters TNF-α levels in the postischemic retina. METHODS. Retinal ischemia was induced by raising the intraocular pressure above systolic blood pressure (155-160 mm Hg) for 45 minutes. Rats were pretreated with the opioid receptor agonist morphine (1 mg/kg; intraperitoneally) before injury. Selected animals were pretreated with the opioid antagonist naloxone (3 mg/kg; intraperitoneally). Human optic nerve head (ONH) astrocytes and rat microglial cells were treated with morphine (0.1-1 μM) for 24 hours and then treated with 10 μg/mL or 30 ng/mL lipopolysaccharide (LPS), respectively. TNF-α was measured by ELISA. Opioid receptor subtypes in astrocytes and microglia were determined by Western blot analysis. RESULTS. There was a time-dependent increase in TNF-α production; the maximum production occurred at 4 hours after ischemia and localized to the inner retinal regions. Ischemiainduced TNF-α production was significantly inhibited by morphine. In astrocytes and microglia, LPS triggered a robust increase in the release of TNF-α, which was significantly inhibited (P < 0.05) by morphine. Naloxone reversed the morphineinduced suppression of TNF-α production in vivo and in vitro. Both ONH astrocytes and microglial cells expressed δ-, κ-, and μ-opioid receptor subtypes. CONCLUSIONS. These data provide evidence that the production of TNF-α after ischemia/reperfusion injury is an early event and that opioid receptor activation reduces the production of TNF-α. Immunohistochemistry data and in vitro studies provide evidence that ONH astrocytes and microglial cells are the primary sources for the TNF-α production under ischemic/inflammatory conditions. Activation of one or more opioid receptors can reduce ischemic/reperfusion injury by the suppression of TNF-α production.
AB - PURPOSE. The detrimental role of TNF-α in ischemia-induced tissue damage is known. The authors study examined whether opioid receptor activation alters TNF-α levels in the postischemic retina. METHODS. Retinal ischemia was induced by raising the intraocular pressure above systolic blood pressure (155-160 mm Hg) for 45 minutes. Rats were pretreated with the opioid receptor agonist morphine (1 mg/kg; intraperitoneally) before injury. Selected animals were pretreated with the opioid antagonist naloxone (3 mg/kg; intraperitoneally). Human optic nerve head (ONH) astrocytes and rat microglial cells were treated with morphine (0.1-1 μM) for 24 hours and then treated with 10 μg/mL or 30 ng/mL lipopolysaccharide (LPS), respectively. TNF-α was measured by ELISA. Opioid receptor subtypes in astrocytes and microglia were determined by Western blot analysis. RESULTS. There was a time-dependent increase in TNF-α production; the maximum production occurred at 4 hours after ischemia and localized to the inner retinal regions. Ischemiainduced TNF-α production was significantly inhibited by morphine. In astrocytes and microglia, LPS triggered a robust increase in the release of TNF-α, which was significantly inhibited (P < 0.05) by morphine. Naloxone reversed the morphineinduced suppression of TNF-α production in vivo and in vitro. Both ONH astrocytes and microglial cells expressed δ-, κ-, and μ-opioid receptor subtypes. CONCLUSIONS. These data provide evidence that the production of TNF-α after ischemia/reperfusion injury is an early event and that opioid receptor activation reduces the production of TNF-α. Immunohistochemistry data and in vitro studies provide evidence that ONH astrocytes and microglial cells are the primary sources for the TNF-α production under ischemic/inflammatory conditions. Activation of one or more opioid receptors can reduce ischemic/reperfusion injury by the suppression of TNF-α production.
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U2 - 10.1167/iovs.10-5629
DO - 10.1167/iovs.10-5629
M3 - Article
C2 - 21282567
AN - SCOPUS:79956052517
SN - 0146-0404
VL - 52
SP - 2577
EP - 2583
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 5
ER -