Immunohistochemical localization of β1-adrenergic receptors in the liver of male and female F344 rat

Abstract

The distribution of beta(1)-adrenergic receptors in the liver of Fischer 344 (F344) rat has been examined by an immunohistochemical method. The study was carried out on formalin-fixed and paraffin-embedded livers from young adult, middle-aged, and old female and male F344 rats. An antibody specific for the beta(1)-adrenoreceptor subtype was used. A positive reaction was found in the liver parenchyma of female and male rats from all age groups. Within the liver lobule, a clear zonation is observed, with the beta(1)-adrenoreceptor positivity most evident in pericentral zone hepatocytes and a gradual fading of the immunostaining from pericentral to periportal zone hepatocytes, which may be completely negative. Immunoreactivity is localized on the cell membrane and on the membrane of peripheral cytoplasmic vesicles, and is mostly confined to the cell side facing vascular space. The intensity of immunostaining seems to be slightly higher in the 6- and 10-month-old female rats as compared to the matched male rats and to the senescent female rats. No age-related changes in the intensity of immunostaining are appreciable in male rats. However, no definite conclusion could be drawn about the existence of gender-related differences or age-related changes in the density of beta(1)-adrenoreceptors. A low density of beta1-adrenoreceptor was observed in the spontaneous preneoplastic lesions of the livers from senescent rats.

Dobutamine Improves Liver Function after Hemorrhagic Shock through Induction of Heme Oxygenase-1

“…Dobutamine pretreatment dose-dependently induced HO-1 in pericentral hepatocytes. The observed zonal expression pattern of HO-1 correlates with the previously described zonal expression pattern of ␤ 1 -adrenoceptors in the liver (30). To avoid the possibility that dobutamine might directly influence hepatocellular function and sinusoidal perfusion by raising cardiac output and liver blood flow, administration of the drug was terminated 30 min before the onset of hemorrhagic shock.…”

α-1 adrenergic receptor agonists modulate ductal secretion of BDL rats via Ca2+- and PKC-dependent stimulation of cAMP

“…Although the adrenergic receptors are preferentially distributed in the basolateral membrane of cholangiocytes, the internalization due to different stimuli (e.g., stress due to handling before anesthesia, which is a powerful stressor) can explain the cytoplasmic staining observed by immunohistochemistry in liver sections. In support of this, studies have shown 37 that the majority of ␤-1 adrenergic receptors is localized on the membrane of peripheral cytoplasmic vesicles as a result of the internalization of surface receptors before killing. The internalization of adrenergic receptors is due to a dramatic rise in plasma catecholamines, which is induced by stress.…”

Innervation of immune cells: Evidence for neuroimmunomodulation in the liver

“…Noradrenalin appears to act via β2 receptors since pretreatment with the specific β2 agonist salbutamol dose‐dependently and significantly reduced plasma levels of ALT, TNF‐α, and IFN‐γ in both GalN/SEB‐ and ConA‐induced experimental hepatitis (Tiegs et al, 1999). β‐adrenergic receptors have been described on T‐cells, macrophages, dendritic cells, and also hepatocytes (Morgan et al, 1983; Elenkov et al, 1995; Ignatowski and Spengler, 1995; Cardani and Zavanella, 2001; Seiffert et al, 2002). In immune cells, β2 stimulation reduces cytokine production, whereas the classical adrenergic effect in hepatocytes is glycogenolysis.…”