Nicotinamide treatment reduces behavioral impairments and provides cortical protection after fluid percussion injury in the rat

The effects of nicotinamide on apoptosis and blood-brain barrier breakdown following traumatic brain injury

Nicotinamide has been shown to protect against many of the pathophysiological factors associated with both ischemic and traumatic brain injuries. The present study evaluated the neuroprotective effect of nicotinamide on the breakdown of the blood-brain barrier (BBB) and apoptosis expression following traumatic brain injury (TBI). Animals were prepared with a unilateral cortical contusion injury (CCI). Fifteen minutes following injury the animals received either nicotinamide (500 mg/kg, ip) or 0.9% saline. The animals were perfused at 5, 24, and 72 h post-injury. BBB integrity was assessed by endogenous rat IgG immunoreactivity. Recent studies have shown that IgG immunoreactivity is a reliable measure of BBB integrity. The results indicated that IgG immunoreactivity was greatest at 5 h and declined at 24 h after injury. Nicotinamide significantly reduced IgG expression at every time point following injury. Apoptosis was examined using the TUNEL method. The results indicated that TUNEL immunoreactivity peaked at 24 h. TUNEL(+) cells were classified morphologically as nonapoptotic (Type I) or apoptotic (Type II) to verify that the neuroprotective effects of nicotinamide occur by inhibiting apoptosis or necrosis. Administration of nicotinamide significantly reduced the expression of all TUNEL(+) cells in the tissue surrounding the lesion cavity. Specifically there was a significant reduction in the number of Type I, Type II, and Total TUNEL(+) cells in the nicotinamide-treated animals. In addition, nicotinamide reduced lesion cavity expansion 72 h following CCI. These findings suggest that nicotinamide reduces BBB breach and neuronal cell loss acutely following injury and that these reductions may account for the beneficial behavioral effects seen in previous studies.

Nicotinamide reduces acute cortical neuronal death and edema in the traumatically injured brain

Previous studies have shown that administration of nicotinamide (Vitamin B(3)) in animal models of traumatic brain injury (TBI) and ischemia significantly reduced the size of infarction or injury and improved functional recovery. The present study evaluated the ability of nicotinamide to provide acute neuroprotection and edema reduction following TBI. Groups of rats were assigned to nicotinamide (500mg/kg) or saline (1.0ml/kg) treatment conditions and received contusion injuries or sham surgeries. Drug treatment was administered 15min following injury. Brains were harvested 24h later and either processed for histology or water content. Frozen sections were stained with the degenerating neuron stain (Fluoro-Jade B) (FJ) and cell counts were performed at the site of injury. Additional brains were processed for water content (a measure of injury-induced edema). Results of this study showed that administration of nicotinamide following TBI significantly reduced the number of FJ(+) neurons in the injured cortex compared to saline-treated animals. Examination of the water content of the brains also revealed that administration of nicotinamide significantly attenuated the amount of water compared to saline-treated animals in the injured cortex. These results indicate that nicotinamide administration significantly reduced neuronal death and attenuated cerebral edema following injury. The current findings suggest that nicotinamide significantly modulates acute pathophysiological processes following injury and that this may account for its beneficial effects on recovery of function following injury.