Growth Hormone Effects on Hypoxia-Induced Neuroinflammation in the Developing Cerebellum

The central nervous system is highly vulnerable to oxygen deprivation during the neonatal period, leading to long-term neurological damage. Growth hormone (GH) has shown neuroprotective and neuroregenerative effects in response to hypoxic injury. This study investigated GH effects on cell survival, inflammatory, and glial activation markers in the developing cerebellum, as well as its impact on motor coordination and anxiety-like behaviors in adulthood following neonatal hypoxia. Global hypoxia was induced in postnatal day 2 Wistar rats (8% O₂, 2 h), followed by subcutaneous GH treatment (0.1 mg/kg/d) for five days. Neonatal hypoxia triggered a sustained inflammatory response in the developing cerebellum, with increased expression of TLR-4, IL-1β, TNF-α, IL-6, COX-2, iNOS, and pNF-κB, persistent gliosis, myelin disruption, and Purkinje cell loss, leading to impaired adult behavior. GH exhibited a biphasic effect-initially proinflammatory, then anti-inflammatory-ultimately downregulating proinflammatory markers and activating prosurvival pathways (pStat5, pErk1/2, pAkt, Bcl-2, TNF-R2, IGF-1). GH also reduced microglial (Iba-1) and astrocytic (GFAP) hypertrophy, restored MBP and β-III tubulin levels, enhanced Purkinje cell survival, and improved motor coordination and anxiety-like behavior in adulthood. These findings demonstrate that GH modulates the cerebellar inflammatory response and supports its therapeutic potential to counteract neuroinflammation and dysfunction following neonatal hypoxic injury.