Kristian Doyle

Here we provide a standardized protocol for performing distal middle cerebral artery occlusion (DMCAO) in mice. DMCAO is a method of inducing permanent focal ischemia that is commonly used as a rodent stroke model. To perform DMCAO a temporal craniotomy is performed, and the middle cerebral artery (MCA) is permanently ligated at a point downstream of the lenticulostriate branches. The size of the lesion produced by this surgery is strain dependent. In C57BL/6J mice, DMCAO produces an infarct predominantly restricted to the barrel region of the somatosensory cortex, but in BALB/cJ mice, DMCAO generates a much larger lesion that incorporates more of the somatosensory cortex and part of the M1 region of the motor cortex. The larger lesion produced by DMCAO in BALB/cJ mice produces a clearer sensorimotor deficit, which is useful for investigating recovery from stroke. We also describe how to modify DMCAO in C57BL/6J mice with the application of hypoxia to generate a lesion and sensorimotor deficit that are similar in size to those produced by DMCAO alone in BALB/cJ mice. This is extremely useful for stroke experiments that require a robust sensorimotor deficit in transgenic mice created on a C57BL/6J background.

Mild hypothermia confers profound neuroprotection in ischemia. We recently discovered 2 natural derivatives of thyroxine, 3-iodothyronamine (T(1)AM) and thyronamine (T(0)AM), that when administered to rodents lower body temperature for several hours without induction of a compensatory homeostatic response. We tested whether T(1)AM- and T(0)AM-induced hypothermia protects against brain injury from experimental stroke.

The present study was conducted to test predictions of the oxidative stress theory of aging assessing reactive oxygen species production and oxidative stress resistance in cultured fibroblasts from 13 primate species ranging in body size from 0.25 to 120 kg and in longevity from 20 to 90 years. We assessed both basal and stress-induced reactive oxygen species production in fibroblasts from five great apes (human, chimpanzee, bonobo, gorilla, and orangutan), four Old World monkeys (baboon, rhesus and crested black macaques, and patas monkey), three New World monkeys (common marmoset, red-bellied tamarin, and woolly monkey), and one lemur (ring-tailed lemur). Measurements of cellular MitoSox fluorescence, an indicator of mitochondrial superoxide (O2(·-)) generation, showed an inverse correlation between longevity and steady state or metabolic stress-induced mitochondrial O2(·-) production, but this correlation was lost when the effects of body mass were removed, and the data were analyzed using phylogenetically independent contrasts. Fibroblasts from longer-lived primate species also exhibited superior resistance to H(2)O(2)-induced apoptotic cell death than cells from shorter-living primates. After correction for body mass and lack of phylogenetic independence, this correlation, although still discernible, fell short of significance by regression analysis. Thus, increased longevity in this sample of primates is not causally associated with low cellular reactive oxygen species generation, but further studies are warranted to test the association between increased cellular resistance to oxidative stressor and primate longevity.