Water channel changes in astrocytes associated with buprenorphine administration in a rat model of diffuse traumatic brain injury

Traumatic brain injury (TBI) is a significant concern, with millions sustaining a TBI each year. The vast majority are categorized as mild, in which diffuse pathologies are the hallmark and multiple cell types are affected, including astrocytes. Buprenorphine (bup), a semi-synthetic opioid, is a common human and veterinary analgesic. Previous studies from our group showed that a single dose of slow-release bup administered acutely following TBI alters astrocyte morphology at 1 day and 4 weeks post-injury in a region-specific manner. The current study expands on these findings by examining how four major astrocyte-associated proteins, GFAP, SWELL1/LRRC8A, TRPM4, and AQP4, are affected by such a dose of bup. Adult male rats received either sham or TBI via a central fluid percussion injury model, followed by saline or bup 15 min following injury. Protein quantification at 1 day and 4 weeks post-injury revealed region- and time-dependent effects of acute bup administration. Specifically, bup reduced hippocampal GFAP, increased cortical TRPM4, and elevated thalamic AQP4 and SWELL1 at 4 weeks following TBI. Taken together, these findings indicate that a single post-injury dose of bup can alter major astrocytic protein expression beyond the acute phase in a region- and time-dependent manner.