Age-dependent increase in Thy-1 protein in the rat supraoptic nucleus

Jason M Askvig; Talia S Dalzell; Nadia Toumeh; Phillip T Kuball; Sara T Whiteman; Erik W Bye; Marissa J Andersen; Michael G McCarthy; Riley E Irmen; Sydney H Bexell; Molly M Benolken; Brooke L Maruska; Shelby E Nordmann

doi:10.1016/j.heliyon.2020.e03501

Age-dependent increase in Thy-1 protein in the rat supraoptic nucleus

Heliyon. 2020 Mar 9;6(3):e03501. doi: 10.1016/j.heliyon.2020.e03501. eCollection 2020 Mar.

Affiliation

¹ Department of Biology, Concordia College, Moorhead, MN, 56562, USA.

Abstract

Mature mammalian CNS neurons often do not recover successfully following injury. To this point, unilateral lesion of the hypothalamo-neurohypophysial tract results in collateral sprouting from uninjured axons of the supraoptic nucleus (SON) in 35-day-old but not in 125-day-old rats. Thus, it appears that there are age-related changes within the SON that preclude the older rat from recovering following axotomy. We hypothesize that the intrinsic capacity for axon reorganization may depend, in part, on age-related alterations in cell adhesion molecules that allow normal astrocyte-neuron interactions in the SON. In support of our hypothesis, numerous reports have shown that Thy-1 is increased in neurons at the cessation of axon outgrowth. Therefore, we compared protein levels of Thy-1 and the Thy-1 interacting integrin subunits, alpha-v (α_v), beta-3 (ß₃), and beta-5 (ß₅), in 35- and 125-day-old SON using western blot analysis. Our results demonstrated that there was significantly more Thy-1 protein in the 125-day-old SON compared to 35-day-old SON, but no change in the protein levels of the integrin subunits. Furthermore, we localized Thy-1-, α_v integrin-, ß₃ integrin-, and ß₅ integrin-immunoreactivity to both neurons and astrocytes in the SON. Altogether, our results suggest that the observed increase in Thy-1 protein levels in the SON with age may contribute to an environment that prevents collateral axonal sprouting in the SON of the 125-day-old rat.

Keywords: Cell biology; Cell death; Dual-label fluorescence; Magnocellular neurosecretory system; Membrane; Nervous system; Neural lobe; Neuronal death; Neuroscience; Western blot; ß3 integrin; ß5 integrin; αv integrin.