Beta2-adrenergic receptor agonists reduce proliferation but not protein synthesis of periodontal fibroblasts stimulated with platelet-derived growth factor-BB

OBJECTIVE Catecholamines released from β-adrenergic neurons upon stress can interfere with periodontal regeneration. The cellular mechanisms, however, are unclear. Here, we assessed the effect of catecholamines on proliferation of periodontal fibroblasts. METHODS Fibroblasts from the gingiva and the periodontal ligament were exposed to agonists of the β-adrenergic receptors; isoproterenol (ISO, non-selective β-adrenergic agonist), salbutamol (SAL, selective β2-adrenergic receptor agonist) and BRL 37344 (BRL selective β3-receptor agonist). Proliferation was stimulated with platelet-derived growth factor-BB (PDGF-BB). Pharmacological inhibitors and gene expression analysis further revealed β-adrenergic signalling. RESULTS Gingiva and periodontal ligament fibroblast express the β2-adrenergic receptor. ISO and SAL but not BRL decreased proliferation of fibroblasts in the presence of PDGF-BB. The inhibitory effect of β-adrenergic signalling on proliferation but not protein synthesis in response to PDGF-BB was reduced by propranolol, a non-selective β-adrenergic antagonist. CONCLUSIONS These results suggest that β2-receptor agonists can reduce the mitogenic response of periodontal fibroblasts. These data add to the compelling concept that blocking of β2-receptor signalling can support tissue maintenance and regeneration.

Ein Forschungsreisender als Notbehelf: Hermann von Wissmann und der erste Überseeeinsatz des Deutschen Reichs (1889-1891)

When the German government faced for the first time an irregular war in German East Africa in 1888, it realised that it did not have the necessary means for such a conflict. Hermann Wissmann, an explorer, was therefore given the mandate to form and lead a force of mercenaries that was bound to him personally on the basis of contracts. Although Wissmann was successful in crushing the disturbances, the government of the Reich refused to give him a leading administrative position in the new formed protectorate subordinate directly to the Kaiser. It feared that the entrepreneur of violence, which had up to then been backed up, would not accept the regulations of colonial rule that should be implemented. Soon, however, it became clear that due to entrenched local views on sovereignty and legitimacy it would be difficult to transfer the western European concept of the monopoly of the state on violence to Africa.