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Subacute intranasal administration of tissue plasminogen activator increases functional recovery and axonal remodeling after stroke in rats.

ABSTRACT: As a thrombolytic agent, application of recombinant tissue plasminogen activator (tPA) to ischemic stroke is limited by the narrow time window and side effects on brain edema and hemorrhage. This study examined whether tPA, administered by intranasal delivery directly targeting the brain and spinal cord, provides therapeutic benefit during the subacute phase after stroke. Adult male Wistar rats were subjected to permanent right middle cerebral artery occlusion (MCAo). Animals were treated intranasally with saline, 60 ?g or 600 ?g recombinant human tPA at 7 and 14days after MCAo (n=8/group), respectively. An adhesive-removal test and a foot-fault test were used to monitor functional recovery. Biotinylated dextran amine (BDA) was injected into the left motor cortex to anterogradely label the corticorubral tract (CRT) and the corticospinal tract (CST). Naive rats (n=6) were employed as normal control. Animals were euthanized 8 weeks after stroke. Compared with saline treated animals, significant functional improvements were evident in rats treated with 600 ?g tPA (p<0.05), but not in 60 ?g tPA treated rats. Furthermore, 600 ?g tPA treatment significantly enhanced both CRT and CST sprouting originating from the contralesional cortex into the denervated side of the red nucleus and cervical gray matter compared with control group (p<0.01), respectively. The behavioral outcomes were highly correlated with CRT and CST axonal remodeling. Our data suggest that delayed tPA intranasal treatment provides therapeutic benefits for neurological recovery after stroke by, at least in part, promoting neuronal remodeling in the brain and spinal cord.

SUBMITTER: Liu Z

PROVIDER: S-EPMC3259280 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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Subacute intranasal administration of tissue plasminogen activator increases functional recovery and axonal remodeling after stroke in rats.

Liu Zhongwu Z Li Yi Y Zhang Li L Xin Hongqi H Cui Yisheng Y Hanson Leah R LR Frey William H WH Chopp Michael M

Neurobiology of disease 20111115 2

As a thrombolytic agent, application of recombinant tissue plasminogen activator (tPA) to ischemic stroke is limited by the narrow time window and side effects on brain edema and hemorrhage. This study examined whether tPA, administered by intranasal delivery directly targeting the brain and spinal cord, provides therapeutic benefit during the subacute phase after stroke. Adult male Wistar rats were subjected to permanent right middle cerebral artery occlusion (MCAo). Animals were treated intran ...[more]

PMID: 22115941

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Project description:We previously reported that intranasal insulin protects substantia nigra dopaminergic neurons against 6-hydroxydopamine neurotoxicity in rats. This study aimed to assess insulin pharmacokinetics in the rat brain following intranasal application. Recombinant human insulin (rh-Ins) or phosphate buffer solution was administered to both nostrils of rats. Animals were sacrificed at 15 minutes, 1, 2, and 6 hours to determine insulin levels in different brain regions by an ultrasensitive, human-specific enzyme-linked immunosorbent assay kit. For fluorescence tracing study, rats were administered with intranasal florescence-tagged insulin (Alex546-Ins), and brains were fixed at 10 and 30 minutes to prepare sagittal sections. rh-Ins was detected in all brain regions examined except the cerebral cortex. The highest levels were detected in the brainstem, followed by the cerebellum, substantia nigra/ventral tegmental area, olfactory bulb, striatum, hippocampus, and thalamus/hypothalamus. Insulin levels reached a peak at 15 minutes and then declined gradually overtime, but remained significantly higher than baseline levels at 6 hours in most regions. Consistently, widespread Alex546-Ins-binding cells were detected in the brain at 10 and 30 minutes, with the olfactory bulb and brainstem showing the highest while the cerebral cortex showing lowest fluorescence signals. Double-immunostaining showed that Alex546-Ins-bindings were primarily co-localized with neuronal nuclei-positive neurons. In the subtantia nigra, phospho-Akt was found to be activated in a subset of Alex546-Ins and tyrosine hydroxylase double-labeled cells, suggesting activation of the Akt/PI3K pathway in these dopaminergic neurons. Data from this study suggest that intranasal insulin could effectively reach deep brain structures including the nigrostriatal pathways, where it binds to dopaminergic neurons and activates intracellular cell survival signaling. This study was approved by the Institutional Animal Care Committee at the University of Mississippi Medical Center (protocol 1333A) on June 29, 2015.

Dataset Information

Subacute intranasal administration of tissue plasminogen activator increases functional recovery and axonal remodeling after stroke in rats.

Publications

Subacute intranasal administration of tissue plasminogen activator increases functional recovery and axonal remodeling after stroke in rats.

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