Introduction: Sodium butyrate (NaB) is a histone deacetylase (HDAC) inhibitor exhibiting anti-inflammatory and neuroprotective effects in a rat ischemic model of a myocardial ischemia as well as stroke. Although clinical evidence shows that older women are at higher risk for stroke occurrence and greater stroke severity, no studies have evaluated the effectiveness of NaB either in females or in older animals.
Methods: To determine the effects of NaB on stroke in older females, acyclic middle-aged Sprague-Dawley female rats (10-12 months old, constant diestrus) were subject to middle cerebral artery occlusion (MCAo) by intracerebral injection of recombinant endothelin-1. Rats were treated with NaB (300 mg/kg, i.p.) at 6h and 30h following ET-1 injection. Animals were tested for sensory motor performance pre and post stroke. Subsequently, rats were sacrificed at the early (2d) or late (5d) acute phase after MCAo. Serum and tissue samples were collected for biochemical analyses.
Results: NaB treatment reduced infarct volume and ameliorated stroke-induced sensory motor impairment in middle-aged female rats post MCAo. At the early acute phase, NaB treatment decreased brain lipid peroxides, and reduced serum levels of GFAP, a marker of blood brain barrier permeability. NaB also reduced expression of the inflammatory cytokine IL-1beta in circulation and IL-18 in the ischemic hemisphere. At the late acute phase, NaB treatment further suppressed MCAo-induced increase of IL-1beta, IL-17A, and IL-18 in brain lysates (cortex and striatum) from the ischemic hemisphere, and decreased ischemia-induced upregulation of IL-1beta and IL-18 in circulation, indicating a potent anti-inflammatory effect of the HDAC inhibitor. Moreover, NaB treatment also increased expression of IGF-1, a known neuroprotectant, in peripheral tissues including serum, liver, and spleen.
Conclusions: These data provide the first evidence that delayed (> 6h) NaB treatment post-stroke is neuroprotective in older female rats. Importantly, these data also show that in addition to its well-known anti-inflammatory actions, NaB may exert a biphasic effect after stroke, operating initially to reduce oxidative stress in the brain, and later, elevating IGF-1 expression in peripheral tissues.