Age-Related Changes in the Adrenergic Control of Glycogenolysis in Rat Liver: The Significance of Changes in Receptor Density

Abstract

25. Raul F, Noriega R, Ngi-Emvo E, Doffoel M, Grenier JF 1983 Lactase activity is under hormonal control in the intestine of adult rat. ABSTRACT. The present study examined the developAbbreviations mental changes in the adrenergic control of glycogenolysis in the rat model. A relatively new P-adrenergic radioligand, '251-iodocyanopindolol (ICP), was examined in binding assays with rat liver plasma membrane (LPM). I C P demonstrated both a higher specificity and a greater affinity for P-adrenergic receptors than any previously available Padrenergic radioligand used to study rat LPM. Utilizing this new ligand it was found that P-adrenergic receptor density decreased from 114 + 4 fmol mg-' in newborn L P M to 1 9 +. 3 fmol mg-' in adult male LPM. In contrast Vol. 19, No. 8. 1985 Prinrcd in U. S.A.CAMP, 3':5'-cyclic adenosine monophosphate GFP, guanosine triphosphate Gpp(NH)p, guanylyl-imidodiphosphate ICP, '251-iodocyanopindolol LPM, liver plasma membrane Kd. dissociation constant a-adrenergic receptor density examined using 3H-prazosin The mechanism of action of epinephrine on liver glycogenoincreased from 161 -c 1 4 fmol mg-' in the newborn to 554 iysis varies depending on a number of factors. In species ' 59 fmo' mg-' in the ma'e' The of ICP such as the guinea pig and rabbit epinephrine-induced glycogendisplacenient assays employing various P-adrenergic olysis is mediated by the @-adrenergic receptor system (1,2) while agonsists and antagonists indicated that ICP binding sites in the adult male rat the system predominates (3, were P2-adrenergic receptors' Both triphosphate 4). In the adult female rat glycogenolysis has recently been shown and its nonhydrolyzable synthetic analog guanylyl-imido-to be under the influence of both a-and P-adrenergic stimuli (4). d i~h O s~h a t e lowered the for ICP Several recent studies have also the impoflance of binding sites similarly in newborn and adult LPM. Thus the age of the experimental animals on the adrenergic control of the of receptor to guanine nucleotide g~ycogeno~ysis~ In these investigations it was demonstrated that protein appeared to be same in both age groups ex-P-adrenergic stimuli resulted in a marked rise in CAMP levels in amined. In isolated hepatocytes glycogen phosphorylase activation was mediated by B2-adrenergic stimi~li in the hepatocytes from juvenile rats but little rise was noted in the hepatocytes from adult male rats. They also showed that glucose and a-adrenergic in the release from the cells occurred following both a-and 0-adrenergic adult male. These results suggest that the change in glycogen phosphorylase activation from P-to predominantly stimuli in the juvenile hepatocytes but only following a-adrenergic stimulation in the adult hepatocytes (5. 6). In another study a-adrenergic mechanisms seen with maturation is related Using cultured fetal hepalocyles and glyto changes in receptor density-(Pediar Res 19:862--868, cogeIlo~ysis were mediated solely by padrenergic (7). 1985However, the results of this study must be questioned since it has r...

Age‐related changes in DNA synthesis stimulated by epinephrine and isoproterenol in primary cultured rat hepatocytes

“…It is well known that the beta-adrenergic receptor stimulates intracellular CAMP formation by G-protein-mediated activation of adenylate cyclase. There are several reports that beta-receptor density and adenylate cyclase activity increase in liver during aging (Bendeck and Noguchi, 1985;Graham et al, 1987;Katz et al, 1987). Recently, several reports have also suggested that G-protein couplinghncoupling to betaadrenergic receptors is impaired during aging and disease (Anwar et al, 1991;Feldman et al, 1984;Montarnat and Davies, 1989).…”

Characterization of prostaglandin‐F 2α‐binding sites on rat hepatocyte plasma membranes

“…The calculated density of the low-affinity binding site is in the same range as the number of copies in each hepatocyte found for other receptors involved in metabolic regulation, e.g. the a,-receptor with about 500 fmol/mg membrane protein [47,43], or the insulin receptor for which receptor numbers of 10000 copies/cell in binding studies [39,40] or 100000 copies/cell in morphometric studies [38] have been reported.…”

Lack of V1 vasopressin receptors in rabbit hepatocytes

“…It should be noted that for the adrenergic agonists clear-cut differences in sensitivity and effectiveness have been reported between young and adult rats [1,2], male and female rats [3], and between different animal species: dog [4] and rabbit [5] hepatocytes display a greater sensitivity to ,-adrenergic agonists than do rat hepatocytes, whereas the liver of rabbit and guinea pig has more ,?than a-receptors [6]. Finally, a complete lack of vasopressin receptors has been reported in the liver of ob/ob mice as compared with their lean controls [7].…”