Large area fractional laser treatment of mouse skin increases energy expenditure.

Fractional laser (FL) treatment is a common dermatologic procedure that generates arrays of microscopic treatment zones separated by intact tissue, promoting fast wound healing. Using a mouse model, we introduced a large area fractional laser treatment (LAFLT) method to study metabolic effects. Using two laser modalities, ablative FL (AFL) and non-ablative FL (NAFL), and exposing different percentages of mice's total body surface area (TBSA), we followed changes in metabolic parameters in real time using metabolic cages. Additionally, body composition, markers of inflammation, neurohormonal signaling, and browning of adipocytes were investigated. LAFLT, especially in high TBSA groups, had specific metabolic effects such as significantly increased average daily energy expenditure, increased fat mass loss, systemic browning of adipocytes, and inflammatory states, without compromising other organs. The ability of LAFLT to stimulate metabolism in a controlled way could develop into a promising therapeutic treatment to induce positive metabolic changes that replace or augment systemic drugs.

Assessing the impact of aging and blood pressure on dermal microvasculature by reactive hyperemia optical coherence tomography angiography.

Visualization and quantification of the skin microvasculature are important for studying the health of the human microcirculation. We correlated structural and pathophysiological changes of the dermal capillary-level microvasculature with age and blood pressure by using the reactive hyperemia optical coherence tomography angiography (RH-OCT-A) technique and evaluated both conventional OCT-A and the RH-OCT-A method as non-invasive imaging alternatives to histopathology. This observational pilot study acquired OCT-A and RH-OCT-A images of the dermal microvasculature of 13 young and 12 old healthy Caucasian female subjects. Two skin biopsies were collected per subject for histological analysis. The dermal microvasculature in OCT-A, RH-OCT-A, and histological images were automatically quantified and significant indications of vessel rarefaction in both old subjects and subjects with high blood pressure were observed by RH-OCT-A and histopathology. We showed that an increase in dermal microvasculature perfusion in response to reactive hyperemia was significantly lower in high blood pressure subjects compared to normal blood pressure subjects (117% vs. 229%). These results demonstrate that RH-OCT-A imaging holds functional information of the microvasculature with respect to physiological factors such as age and blood pressure that may help to monitor early disease progression and assess overall vascular health. Additionally, our results suggest that RH-OCT-A images may serve as a non-invasive alternative to histopathology for vascular analysis.

Improved tools for the Brainbow toolbox.

In the transgenic multicolor labeling strategy called 'Brainbow', Cre-loxP recombination is used to create a stochastic choice of expression among fluorescent proteins, resulting in the indelible marking of mouse neurons with multiple distinct colors. This method has been adapted to non-neuronal cells in mice and to neurons in fish and flies, but its full potential has yet to be realized in the mouse brain. Here we present several lines of mice that overcome limitations of the initial lines, and we report an adaptation of the method for use in adeno-associated viral vectors. We also provide technical advice about how best to image Brainbow-expressing tissue.

Improved tools for the Brainbow toolbox.

In the transgenic multicolor labeling strategy called 'Brainbow', Cre-loxP recombination is used to create a stochastic choice of expression among fluorescent proteins, resulting in the indelible marking of mouse neurons with multiple distinct colors. This method has been adapted to non-neuronal cells in mice and to neurons in fish and flies, but its full potential has yet to be realized in the mouse brain. Here we present several lines of mice that overcome limitations of the initial lines, and we report an adaptation of the method for use in adeno-associated viral vectors. We also provide technical advice about how best to image Brainbow-expressing tissue.

Integrating retinoic acid signaling with brain function.

The vitamin A derivative retinoic acid (RA) regulates the transcription of about a 6th of the human genome. Compelling evidence indicates a role of RA in cognitive activities, but its integration with the molecular mechanisms of higher brain functions is not known. Here we describe the properties of RA signaling in the mouse, which point to unknown means through which RA actions are modified and reinforced at selected brain sites. The locations of RA signaling for the developing dorsal forebrain undergo slow, gradual changes over the life cycle except for two brief periods of accelerated shifts, which coincide with periods of enhanced developmental vulnerability. In the functional cerebral cortex, RA signaling delineates regions with immature, plastic neuronal characteristics, within which the expression of hundreds of genes is differentially regulated. Many of these are involved in neuronal ligand-receptor interactions and signaling cascades for activity dependent gene expression. We propose that RA functions in the brain by contributing topographical information and life cycle changes to combinatorial transcriptional mechanisms and that in the postnatal cortex RA signaling designates domains of modifiable neuronal circuitry.

Defects in tangential neuronal migration of pontine nuclei neurons in the Largemyd mouse are associated with stalled migration in the ventrolateral hindbrain.

The LARGE gene encodes a putative glycosyltransferase that is required for normal glycosylation of dystroglycan, and defects in LARGE can cause abnormal neuronal migration in congenital muscular dystrophy (CMD). Previous studies have focused on radial migration, which is disrupted at least in part due to breaks in the basal lamina. Through analysis of precerebellar nuclei development in the Large(myd) mouse hindbrain, we show that tangential migration of a subgroup of hindbrain neurons may also be disrupted. Within the precerebellar nuclei, the pontine nuclei (PN) are severely disrupted, whereas the inferior olive (IO), external cuneate nuclei (ECN) and lateral reticular nuclei (LRN) appear unaffected. Large and dystroglycan are widely expressed in the hindbrain, including in the pontine neurons migrating in the anterior extramural migratory stream (AES). BrdU labeling and immunohistochemical studies suggest normal numbers of neurons begin their journey towards the ventral midline in the AES in the Large(myd) mouse. However, migration stalls and PN neurons fail to reach the midline, surviving as ectopic clusters of cells located under the pial surface dorsally and laterally to where they normally would finish their migration near the ventral midline. Stalling of PN neurons at this location is also observed in other migration disorders in mice. These observations suggest that glycan-dependent dystroglycan interactions are required for PN neurons to correctly respond to signals at this important migrational checkpoint.

Retinoic acid delineates the topography of neuronal plasticity in postnatal cerebral cortex.

Retinoic acid is well recognized to promote neuronal differentiation in the embryonic nervous system, but how it influences the postnatal cerebral cortex remains largely unknown. The domain of highest retinoic acid actions in the cortex of the mouse constricts postnatally to a narrow band that includes the dorsal visual stream and the attentional and executive networks. This band of cortex, which is distinguished by the retinoic acid-synthesizing enzyme RALDH3, exhibits signs of delayed maturation and enhanced plasticity compared to the surrounding cortex, as indicated by suppression of parvalbumin, neurofilament, cytochrome oxidase and perineuronal net maturation, and persistence of the embryonic, polysialated form of the neural cell-adhesion molecule PSA-NCAM. During the first postnatal week, the RALDH3-expressing territory translocates in the caudal cortex from the medial limbic lobe to the adjacent neocortex. This topographical shift requires the neurotrophin NT-3 because in mice lacking neuronal NT-3 the RALDH3 enzyme maintains its early postnatal pattern up to adulthood. In the NT-3-null mutants, expression of the markers, whose topography colocalizes with RALDH3 in the normal cortex, matches the abnormal RALDH3 pattern. This indicates that the uneven retinoic acid distribution serves a role in patterning the maturation and to some extent function of the normal postnatal cerebral cortex.

Retinoids, eye development, and maturation of visual function.

Vitamin A is known to be critical for the beginning of eye development as well as for photoreception in the functional retina. Hardly anything, however, is known about whether retinoic acid (RA)-regulated gene expression also plays a role in the long intervening period, during which the neurobiological retinal structure takes shape. The eye contains a highly intricate architecture of RA-synthesizing (RALDH) and degrading (CYP26) enzymes. Whereas the RALDHs are integrated in the early molecular mechanisms through which the dorso-ventral retina organization is established, the CYP26 enzymes are not necessary for this process and no molecular targets that match their retinal expression pattern have yet been identified. In this article we describe that CYP26 expression in the mouse is most distinctive during later stages of retina formation. Throughout development CYP26A1 degrades RA in a horizontal region that extends across the retina, but during later embryonic and postnatal retina maturation this function is reinforced by another enzyme, CYP26C1. RA applications at this stage do not affect the RALDHs but cause differential changes in CYP26 expression: Cyp26a1 is up-regulated, but more rapidly by 9-cis than all-trans RA, Cyp26c1 is down-regulated, and Cyp26b1, which is undetectable in the normal mouse retina, is strongly activated in retinal ganglion cells. The dynamic regulation in RA-difference patterns by the CYP26 enzymes may set up spatial constellations for expression of genes involved in formation of retinal specializations for higher acuity vision, which are known to form over a prolonged period late in retina development.

A retinoic-acid critical period in the early postnatal mouse brain.

BACKGROUND: A normal supply of vitamin A, which regulates gene expression through its active form retinoic acid, is required by many organs; both excess and deficiency can be teratogenic. Very little is known about the role of retinoic acid in maturation of the mammalian forebrain. METHODS: As retinoic acid cannot be visualized directly, we mapped its actions in the forebrain with indirect morphologic methods and by applying retinoic acid overdoses to early postnatal mice. RESULTS: During this time, the morphologic indicators of retinoic acid actions are localized mainly in the limbic system and they undergo rapid changes. Retinoic acid overdoses can cause lasting behavioral abnormalities that point to disrupted limbic functions. In the anterior cingulate cortex, inhibitory interneurons are affected, and in the hippocampus, primarily the dentate gyrus is abnormal. CONCLUSIONS: Retinoic acid is involved in functional maturation of limbic regions of the forebrain with a critical stage early postnatally in mice, when their brains are particularly vulnerable to vitamin A perturbations. This developmental time in mice compares with the second trimester of gestation in humans, a stage when in genetically predisposed individuals the corresponding brain regions are known to pass through a period of increased susceptibility to environmental disturbances.

CYP26A1 and CYP26C1 cooperate in degrading retinoic acid within the equatorial retina during later eye development.

In the embryonic mouse retina, retinoic acid (RA) is unevenly distributed along the dorsoventral axis: RA-rich zones in dorsal and ventral retina are separated by a horizontal RA-poor stripe that contains the RA-inactivating enzyme CYP26A1. To explore the developmental role of this arrangement, we studied formation of the retina and its projections in Cyp26a1 null-mutant mice. Expression of several dorsoventral markers was not affected, indicating that CYP26A1 is not required for establishing the dorsoventral retina axis. Analysis of the mutation on a RA-reporter mouse background confirmed, as expected, that the RA-poor stripe was missing in the retina and its projections at the time when the optic axons first grow over the diencephalon. A day later, however, a gap appeared both in retina and retinofugal projections. As explanation, we found that CYP26C1, another RA-degrading enzyme, had emerged centrally in a narrower domain within the RA-poor stripe. While RA applications increased retinal Cyp26a1 expression, they slightly reduced Cyp26c1. These observations indicate that the two enzymes function independently. The safeguard of the RA-poor stripe by two distinct enzymes during later development points to a role in maturation of a significant functional feature like an area of higher visual acuity that develops at its location.

Activation of endogenous neural stem cells in experimental intracerebral hemorrhagic rat brains.

BACKGROUND: Many researchers suggest that adult mammalian central nervous system (CNS) is incapable of completing self-repair or regeneration. And there are accumulating lines of evidence which suggest that endogenous neural stem cells (NSCs) are activated in many pathological conditions, including stroke in the past decades, which might partly account for rehabilitation afterwards. In this study, we investigated whether there was endogenous neural stem cell activation in intracerebral hemorrhagic (ICH) rat brains. METHODS: After ICH induction by stereotactical injection of collagenase type VII into globus pallidus, 5-Bromo-2 Deoxyuridine (BrdU) was administered intraperitoneally to label newborn cells. Immunohistochemical method was used to detect Nestin, a marker for neural stem cells, and BrdU. RESULTS: Nestin-positive or BrdU-Labeled cells were predominantly located at 2 sites: basal ganglion around hemotoma, ependyma and nearby subventricular zone (SVZ). No positive cells for the 2 markers were found in the 2 sites of normal control group and sham group, as well as in non-leisioned parenchyma, both hippocampi and olfactory bulbs in the 4 groups. Nestin+ cells presented 4 types of morphology, and BrdU+ nucleus were polymorphologic. Positive cell counting around hemotoma showed that at day 2, Nestin+ cells were seen around hemotoma in model group, the number of which increased at day 4, day 7 (P <0.01), peaked at day 14 (P <0.05), and reduced significantly by day 28 (P <0.01). CONCLUSION: Endogenous neural stem cells were activated in experimental intracerebral hemorrhagic rat brains.

Retinoic acid signaling in the brain marks formation of optic projections, maturation of the dorsal telencephalon, and function of limbic sites.

As retinoic acid (RA) is known to regulate the expression of many neuronal proteins, it is likely to influence overall development and function of the brain; few particulars, however, are available about its role in neurobiological contexts due mainly to problems in RA detection. To ask whether the function of RA in the rostral brain is concentrated in particular neurobiological systems, we compared sites of RA synthesis and actions, as detected by RA signaling in reporter mice, for embryonic and adult ages. We found that most sites of RA actions in the forebrain do not colocalize with RA synthesis, consistent with a dominant RA supply by diffusion and the circulation. The changing RA patterns distinguish preferentially two complex functional schemes. (1) Within the visual system when the first optic axons grow toward their targets, RA signaling delineates the topographical adjustment of the retinal map, which is encoded in the coordinates of the visual world, to central visual maps, which are formed in the segmental brain coordinates. (2) The second scheme begins early in forebrain morphogenesis as a distinction of the dorsal telencephalon. With progressing development, and in the adult, the RA patterns then focus on widely distributed structures, most of which belong to the limbic system. These are sites in which emotional perception is combined with higher cognitive processes and in which normal function requires ongoing remodeling of synaptic connections, indicating that the developmental role of RA in promotion of neuronal differentiation programs continues in the adult brain for highly flexible neural circuits. J. Comp. Neurol. 470:297-316, 2004.

Retinoic acid synthesis in the postnatal mouse brain marks distinct developmental stages and functional systems.

Retinoic acid (RA) affects development and function of the brain, but little is known about how much is made locally and where it is distributed. To identify RA-sensitive neural processes, we mapped the RA-synthesizing retinaldehyde dehydrogenases (RALDHs) during postnatal brain formation of the mouse. High and stable RALDH expressions mark the basal ganglia, olfactory bulbs, hippocampus and auditory afferents as major sites of RA actions in the functional brain. During the early postnatal period, transient and very high RALDH3 expressions distinguish two developmental events: (i) the colonization of the nucleus accumbens and the olfactory bulbs by neuronal precursors and (ii) the maturation of selected parts of the cerebral cortex. In the cortex, RALDH3 is transiently activated in postmigratory layer II/III neurons during formation of their dendritic arbors and it is transported in their axons across the corpus callosum. RALDH3-expressing cortical regions include most of the limbic lobe, with strongest expression in the anterior cingulate cortex, medial and lateral secondary visual cortices, auditory cortical areas, the secondary motor cortex and some association areas. The transient cortical expression points to a brief RA-critical period during differentiation of the cortical network that serves in the coordination of sensory-motor activity with emotional and recently learned information.

[Effects of nao-yi-an granule on the expression of heme oxygenase-1 in brains of intracerebral hemorrhagic rats].

OBJECTIVE: To investigate the effects of the traditional Chinese medicine complex nao-yi-an granule(NYA) on the expression of heme oxygenase-1(HO-1) in the brains of intracerebral hemorrhagic (ICH) rats. METHODS: After inducing ICH rat models with collagenase VII, we used the immunohistochemical method and HO-1 immunoreactive cell count to observe the HO-1 expression. RESULTS: Following ICH, the expression of HO-1 in the rat brains was observed at 12 h, peaking at 2 d and persisting until 7 d; and NYA could increase the expression at 24 h obviously. CONCLUSION: Expression of HO-1 increases following ICH,; upregulation of HO-1 expression may be one of the neuroprotective mechanisms of NYA.