Stereotaxic Surgical Targeting of the Nonhuman Primate Caudate and Putamen: Gene Therapy for Huntington's Disease.

Stereotaxic surgery is an invaluable tool to deliver a variety of gene therapy constructs to the nonhuman primate caudate and putamen in preclinical studies for the genetic, neurodegenerative disorder, Huntington's disease (HD). Here we describe in detail how to perform this technique beginning with a pre-surgical magnetic resonance imaging scan to determine surgical coordinates followed by the stereotaxic surgical injection technique. In addition, we include methodology of a full necropsy including brain and peripheral tissue removal and a standard immunohistochemical technique to visualize the injected gene therapy agent.

Intrajugular vein delivery of AAV9-RNAi prevents neuropathological changes and weight loss in Huntington's disease mice.

Huntington's disease (HD) is a fatal neurological disorder caused by a CAG repeat expansion in the HTT gene, which encodes a mutant huntingtin protein (mHTT). The mutation confers a toxic gain of function on huntingtin, leading to widespread neurodegeneration and inclusion formation in many brain regions. Although the hallmark symptom of HD is hyperkinesia stemming from striatal degeneration, several other brain regions are affected which cause psychiatric, cognitive, and metabolic symptoms. Additionally, mHTT expression in peripheral tissue is associated with skeletal muscle atrophy, cardiac failure, weight loss, and diabetes. We, and others, have demonstrated a prevention of motor symptoms in HD mice following direct striatal injection of adeno-associated viral vector (AAV) serotype 1 encoding an RNA interference (RNAi) construct targeting mutant HTT mRNA (mHTT). Here, we expand these efforts and demonstrate that an intrajugular vein injection of AAV serotype 9 (AAV9) expressing a mutant HTT-specific RNAi construct significantly reduced mHTT expression in multiple brain regions and peripheral tissues affected in HD. Correspondingly, this approach prevented atrophy and inclusion formation in key brain regions as well as the severe weight loss germane to HD transgenic mice. These results demonstrate that systemic delivery of AAV9-RNAi may provide more widespread clinical benefit for patients suffering from HD.

Peptide YY(3-36) inhibits morning, but not evening, food intake and decreases body weight in rhesus macaques.

Peptide YY(3-36) [PYY(3-36)] is a hormone that is released after meal ingestion that is currently being investigated for the treatment of obesity; however, there are conflicting reports of the effects of PYY(3-36) on energy balance in rodent models. To shed light on this controversy, we studied the effect of PYY(3-36) on food intake and body weight in a nonhuman primate. Intravenous PYY(3-36) infusions before a morning meal transiently suppressed the rate of food intake but did not suppress the evening meal or 24-h intake. Twice-daily or continuous intravenous PYY(3-36) infusions to supraphysiological levels (levels that exceeded normal physiological levels) again suppressed the rate of feeding for the morning but not the evening meal. Twice-daily intravenous PYY(3-36) infusions for 2 weeks significantly decreased body weight in all test animals (average weight loss 1.9%) without changing insulin response to glucose infusion. These results show that endogenous PYY(3-36) may alter morning but not evening meal intake, and supraphysiological doses are required for effective suppression of food intake.