During pregnancy, the liver undergoes metabolic adjustments directed to fulfil the needs of the mother and the growing fetus. This study was designed to verify whether relaxin, a hormone related to pregnancy, may induce histochemical and ultrastructural modifications of hepatocytes which can be related to metabolic changes. Estrogen-primed female rats were treated with relaxin (10 µg in repository vehicle) for 18 h. Additional male rats were treated with relaxin (10 µg/day in PBS) for 4 days. Appropriate vehicle-treated rats were used as controls. After fasting, the rats were killed and liver fragments were processed for light and electron microscopy and for computer-assisted morphometry of PAS-positive glycogen deposits and acid phosphatase-reactive organelles. In both sexes, the relaxin-treated rats underwent a significant decrease in the amount of glycogen in the hepatocytes as compared with the controls. These changes were accompanied by an increase in smooth endoplasmic reticulum, endocytosis vesicles and lysosomes. These findings show that relaxin promotes glycogen depletion and induces morphological changes of hepatocytes which are consistent with functional activation. It is suggested that relaxin might play an important role in hepatic metabolic adjustments occurring during pregnancy.
Key words:
Hepatocytes - Hormones of Pregnancy - Glycogen - Lysosomes - Ultrastructure
References
-
1
Schwabe C, Büllesbach E E.
Relaxin: structures, functions, promises, and nonevolution.
FASEB J.
1994;
8
1152-1160
-
2
Sherwood O D, Crnekovic V E, Gordon W L, Rutherford J E.
Radioimmunoassay of relaxin throughout pregnancy and during parturition in the rat.
Endocrinology.
1980;
107
691-698
-
3
Eddie L W, Lester A, Bennett G, Bell R J, Geier M, Johnston P D, Niall H D.
Radioimmunoassay of relaxin in pregnancy with an analogue of human relaxin.
Lancet.
1986;
1 (8494)
1344-1346
-
4
Bani D.
Relaxin: a pleiotropic hormone.
Gen Pharmacol.
1997;
28
13-22
-
5
Vasilenko P, Frieden E H, Adams W C.
Effect of purified relaxin on uterine glycogen and protein in the rat.
Proc Soc Exp Biol Med.
1980;
163
245-248
-
6 Vasilenko P, Mahajan D K. Anabolic effects of relaxin in the uterus and cervix of the rat: comparison between insulin, estrogen, and progesterone. In: M Bigazzi, FC Greenwood (eds). Biology of relaxin and its role in the human. Amsterdam:; Excerpta Medica, 1983: 134-136
-
7
Bylander J E, Frieden E H, Adams W C.
Effects of porcine relaxin upon uterine hypertrophy and protein metabolism in mice.
Proc Soc Exp Biol Med.
1987;
185
76-80
-
8
Bianchi S, Bani G, Bigazzi M.
The effects of relaxin on the mouse mammary gland. III - the fat pad.
J Endocrinol Invest.
1986;
9
153-160
-
9
Bani Sacchi T, Bianchi S, Bani G, Bigazzi M.
Ultrastructural studies on white adipocyte differentiation in the mouse mammary gland following estrogen and relaxin.
Acta Anat.
1987;
129
1-9
-
10
Bani G, Bianchi S, Formigli L, Bigazzi M.
Responsiveness of mouse parametrial fat to relaxin.
Acta Anat.
1989;
134
128-132
-
11 Jaffe R B. Integrative maternal-fetal endocrine control systems. In: Yen SSC, Jaffe RB (eds). Reproductive Endocrinology. Physiology, Pathophysiology and Clinical Management, 2nd edn. Philadelphia:; Saunders, 1986: 770-788
-
12 Freinkel N. Metabolic changes in pregnancy. In: Wilson JD, Foster DW (eds). Textbook of Endocrinology, 7th edn. Philadelphia:; WB Saunders, 1985: 438-451
-
13 Stock M K, Metcalfe J. Maternal physiology during gestation. In: Knobil E, Neill JD (eds). The Physiology of Reproduction, 2nd edn. New York:; Raven Press, 1994: 947-983
-
14
Freetly H C, Ferrell C L.
Net flux of glucose, lactate, volatile fatty acids, and nitrogen metabolites across the portal-drained viscera and liver of pregnant ewes.
J Anim Sci.
1998;
76
3133-3145
-
15
Bani G, Bigazzi M, Bani Sacchi T.
Relaxin as a mammotrophic hormone.
Life Sci Adv-Exp Clin Endocrinol.
1991;
10
143-150
-
16
Mercado-Simmen R C, Bryant-Greenwood G D, Greenwood F C.
Relaxin receptor in the rat myometrium: regulation by estrogen and relaxin.
Endocrinology.
1980;
110
220-226
-
17
Sherwood O D, O’Byrne E M.
Purification and characterization of porcine relaxin.
Arch Biochem Biophys.
1974;
60
185-196
-
18
Babcock M B, Cardell R R.
Hepatic glycogen patterns in fasted and fed rats.
Am J Anat.
1974;
140
299-338
-
19
Masini E, Bani D, Bigazzi M, Mannaioni P F, Bani Sacchi T.
Effects of relaxin on mast cells. In vitro and in vivo studies in rats and guinea pigs.
J Clin Invest.
1994;
94
1974-1980
-
20
Bani D, Filipponi F, Magnani L, Houssin D, Romagnoli P.
Morphological changes in rat pancreatic acinar cells induced by long-term treatment with cyclosporine and their reversal after withdrawal.
Transplantation.
1990;
50
830-834
-
21 Novikoff A B, Novikoff P M. Lysosomes. In: Arias IM, Jakoby WB, Popper H, Schachter D, Shafritz DA (eds). The Liver: Biology and Pathobiology, 2nd edn. New York:; Raven Press, 1988: 227-239
-
22 Phillips M J, Poucell S. Cholestasis: surgical pathology, mechanisms and new concepts. In: Farber E, Phillips MJN, Kaufman N (eds). Pathogenesis of liver diseases. IAP Monograph No. 28. Baltimore:; Williams and Wilkins, 1987: 65-94
-
23 La Russo N F. Hepatocyte lysosomes in intracellular digestion and biliary secretion. In: Schultz SG, Forte JG, Rauner BB (eds). Handbook of Physiology. Section 6: The Gastrointestinal System. Volume III, 2nd edn. New York:; Oxford University Press, 1989: 677-691
-
24 Gumucio J J, Chianale J. Liver cell heterogeneity and liver function. In: Arias IM, Jakoby WB, Popper H, Schachter D, Shafritz DA (eds). The Liver. Biology and Pathobiology, 2nd edn. New York:; Raven Press, 1988: 931-947
Prof. Daniele Bani
Dipartimento di Anatomia
Istologia e Medicina Legale
Sezione di Istologia
V. le G. Pieraccini, 6
50139 Firenze
Italy
Email: E-mail:bani@unifi.it.
