Fetal antisense oligonucleotide therapy for congenital deafness and vestibular dysfunction.

Disabling hearing loss impacts ∼466 million individuals worldwide with 34 million children affected. Gene and pharmacotherapeutic strategies to rescue auditory function in mouse models of human deafness are most effective when administered before hearing onset, after which therapeutic efficacy is significantly diminished or lost. We hypothesize that preemptive correction of a mutation in the fetal inner ear prior to maturation of the sensory epithelium will optimally restore sensory function. We previously demonstrated that transuterine microinjection of a splice-switching antisense oligonucleotide (ASO) into the amniotic cavity immediately surrounding the embryo on embryonic day 13-13.5 (E13-13.5) corrected pre-mRNA splicing in the juvenile Usher syndrome type 1c (Ush1c) mouse mutant. Here, we show that this strategy only marginally rescues hearing and partially rescues vestibular function. To improve therapeutic outcomes, we microinjected ASO directly into the E12.5 inner ear. A single intra-otic dose of ASO corrects harmonin RNA splicing, restores harmonin protein expression in sensory hair cell bundles, prevents hair cell loss, improves hearing sensitivity, and ameliorates vestibular dysfunction. Improvements in auditory and vestibular function were sustained well into adulthood. Our results demonstrate that an ASO pharmacotherapeutic administered to a developing organ system in utero preemptively corrects pre-mRNA splicing to abrogate the disease phenotype.

Elevated ghrelin alters the behavioral effects of perinatal acetaminophen exposure in rats.

A growing body of evidence links prenatal and early postnatal acetaminophen (APAP) exposure to atypical development of brain and behavior. In adult rodents, APAP is known to produce oxidative stress and lower anxiety-related behavior following acute exposure. In models of early-life exposure, APAP has also been shown to alter anxiety-related and other behaviors. Since the neuropeptide ghrelin has been recently shown to reduce oxidative stress markers and act as a neuroprotectant, we hypothesized that exposure to ghrelin prior to exposure to APAP would mitigate the behavioral effects of APAP exposure. On postnatal day 7, pups were administered doses of either APAP (51.97 mg/kg), ghrelin (1 mg/kg/ml), ghrelin + APAP, or vehicle only. As adults, anxiety-related behavior was assessed in the open field and elevated plus maze. Behavior differed based upon treatment condition. In rats unexposed to ghrelin, APAP treatment resulted in increased exploration (i.e., reduced anxiety) in the open field relative to controls. Rats co-administered APAP and ghrelin did not differ from vehicle-only controls. No significant effects of APAP or interactions between APAP and ghrelin exposures were observed in the elevated plus maze. These results are the first to demonstrate that ghrelin can mitigate the effects of perinatal APAP exposure in rats.

Mesolimbic exendin-4 attenuates reward salience evoked by neuropeptide Y and ghrelin.

In the present study, we investigated the effects of the glucagon-like peptide-1 (GLP-1) agonist exendin-4 (Ex-4) on the stimulatory action of neuropeptide Y (NPY) and ghrelin. These effects were examined in relation to operant responding for palatable food or voluntary ethanol intake in a two-bottle limited access paradigm. Male Sprague Dawley rats, each with ventral tegmental area (VTA) unilateral guide cannulae, were used. Ex-4 was paired with either NPY, ghrelin, or combined NPY and ghrelin treatment. Our results indicated that while NPY and ghrelin reliably stimulated operant responding for sucrose pellets and increased ethanol intake, Ex-4 suppressed intake and, most importantly, significantly reduced the effects of NPY and ghrelin. Overall, this work provides compelling evidence that VTA GLP-1, NPY, and ghrelin systems interact within the brain to modulate reward salience.