ß3 Adrenoceptor Agonism Prevents Hyperoxia-Induced Colonic Alterations.

Oxygen level is a key regulator of organogenesis and its modification in postnatal life alters the maturation process of organs, including the intestine, which do not completely develop in utero. The ß3-adrenoreceptor (ß3-AR) is expressed in the colon and has an oxygen-dependent regulatory mechanism. This study shows the effects of the ß3-AR agonist BRL37344 in a neonatal model of hyperoxia-driven colonic injury. For the first 14 days after birth, Sprague-Dawley rat pups were exposed to ambient oxygen levels (21%) or hyperoxia (85%) and treated daily with BRL37344 at 1, 3, 6 mg/kg or untreated. At the end of day 14, proximal colon samples were collected for analysis. Hyperoxia deeply influences the proximal colon development by reducing ß3-AR-expressing cells (27%), colonic length (26%) and mucin production (47%), and altering the neuronal chemical coding in the myenteric plexus without changes in the neuron number. The administration of BRL37344 at 3 mg/kg, but not at 1 mg/kg, significantly prevented these alterations. Conversely, it was ineffective in preventing hyperoxia-induced body weight loss. BRL37344 at 6 mg/kg was toxic. These findings pave the way for ß3-AR pharmacological targeting as a therapeutic option for diseases caused by hyperoxia-impaired development, typical prematurity disorders.

Central retinal artery occlusion in a young child affected by COVID-19: a first case report.

BACKGROUND: Central retinal artery occlusion (CRAO) is an ophthalmic emergency, and its etiology is generally ascribed to vessel occlusion by a thrombus or embolus, eventually due to a hypercoagulable state. CRAO occurrence is described even in the pediatric population, but its incidence is very rare. SARS-CoV-2 infection has a multitude of presentations, and almost any organ may be involved including the ocular district. Cases of CRAO in patients affected by COVID-19 are reported in the literature in the adult population, but not in the pediatric one. CASE PRESENTATION: We describe the case of a six-year-old otherwise healthy girl, who presented a sudden and complete bilateral vision loss after a one-day fever. All the clinical, ophthalmological, laboratory and instrumental investigations led to the diagnosis of a right CRAO and the suspicion of a contralateral posterior optic nerve affection. These manifestations could not be ascribed to any etiological condition apart from the documented ongoing mild SARS-CoV-2 infection. Treatment with anticoagulants and steroids was tried but the visual outcome was poor during the one-month hospitalization and at the last follow-up. CONCLUSIONS: To the best of our knowledge, this is the first report of CRAO in the course of SARS-CoV-2 infection in the pediatric age. In our review of the literature, we found few cases of CRAO in adults with COVID-19; we highlighted differences in anamnestic, clinical, and interventional aspects and therefore we tried to summarize the state of the art on this topic to facilitate further studies. Even if rare, the prognosis of CRAO is poor and the thrombolytic treatment could be effective only if rapidly administered, so the disease suspicion should be high in a patient with sudden vision loss, also in pediatric age.

Effect of Beta 3 Adrenoreceptor Modulation on Patency of the Ductus Arteriosus.

ß3-adrenoreceptor (ß3-AR), a G-protein coupled receptor, has peculiar regulatory properties in response to oxygen and widespread localization. ß3-AR is expressed in the most frequent neoplasms, also occurring in pregnant women, and its blockade reduces tumor growth, indicating ß3-AR-blockers as a promising alternative to antineoplastic drugs during pregnancy. However, ß3-AR involvement in prenatal morphogenesis and the consequences of its blockade for the fetus remain unknown. In this study, after the demonstrated expression of ß3-AR in endothelial and smooth muscle cells of ductus arteriosus (DA), C57BL/6 pregnant mice were acutely treated at 18.5 of gestational day (GD) with indomethacin or with the selective ß3-AR antagonist SR59230A, or chronically exposed to SR59230A from 15.5 to 18.5 GD. Six hours after the last treatment, fetuses were collected. Furthermore, newborn mice were treated straight after birth with BRL37344, a ß3-AR agonist, and sacrificed after 7 h. SR59230A, at the doses demonstrated effective in reducing cancer progression (10 and 20 mg/kg) in acute and chronic mode, did not induce fetal DA constriction and did not impair the DA ability to close after birth, whereas at the highest dose (40 mg/kg), it was shown to cause DA constriction and preterm-delivery. BRL37344 administered immediately after birth did not alter the physiological DA closure.