Abstract
The action of testosterone on the 45Ca2+ uptake and insulin secretion was studied in short-term experiments using isolated pancreatic islets of Langerhans. Testosterone (1 µM) stimulated 45Ca2+ uptake within 60 seconds of incubation on similar proportion than tolbutamide. Also, the hormone rapidly increased insulin release (34 %; 180 seconds) on the presence of non-stimulatory concentrations of glucose (3 mM). Impermeant testosterone-BSA significantly stimulated the secretion of insulin to a lower percentage (10 %). The action of the hormone is specific - neither 17β-E2 nor progesterone stimulated insulin secretion in the presence of 3 mM glucose. The action of testosterone on insulin secretion was dose-dependent, and at rat plasma physiological concentrations (25 nM), stimulus was 17 % (p < 0.05). In conclusion, in isolated pancreatic islets experiments, physiological concentration of testosterone rapidly stimulate insulin secretion and 45Ca2+ uptake through a membrane bound mechanism.
Key words
Testosterone - insulin release - pancreatic islets -
45Ca2+ uptake
References
-
1
Nadal A, Rovira J M, Laribi O, Leon-Quinto T, Andreu E, Ripoll C, Soria B.
Rapid insulinotropic effect of 17β-estradiol via a plasma membrane receptor.
FASEB J.
1998;
12
1341-1348
-
2
Ropero A B, Fuentes E, Rovira J M, Ripoll C, Soria B, Nadal A.
Non-genomic actions of 17β-estradiol in mouse pancreatic β-cells are mediated by a cGMP-dependent protein kinase.
J Physiol.
1999;
521.2
397-407
-
3
Morimoto S, Fernandez-Mejia C, Romero-Navarro G, Morales-Peza N, Díaz-Sánchez V.
Testosterone effect on insulin content, messenger ribonucleic acid levels, promoter activity, and secretion in the rat.
Endocrinology.
2001;
142
1442-1447
-
4
Sturgess N C, Ashford M L, Cook D L, Hales C N.
The sulphonylurea receptor may be an ATP-sensitive potassium channel.
Lancet.
1985;
2
474-475
-
5
Ashcroft F M, Gribble F M.
ATP-sensitive K+ channels and insulin secretion: their role in health and disease.
Diabetologia.
1999;
42
903-919
-
6
Miranda M J, Liedke P ER, Leite L, Loss E S, Wassermann G F.
Glibenclamide changes membrane potential and stimulates 45Ca2+ uptake and amino acid accumulation in Sertoli cells of immature rats.
Med Sci Res.
1998;
26
703-706
-
7
von Ledebur E ICF, Almeida J P, Loss E S, Wassermann G F.
Rapid effect of testosterone on rat Sertoli cell membrane potential. Relationship with K+ATP channels.
Horm Metab Res.
2002;
34
550-555
-
8
Loss E S, Jacobsen M, Costa Z SM, Jacobus A P, Borelli F, Wassermann G F.
Testosterone modulates K+
ATP channels in Sertoli cell membrane via the PLC-PIP2 pathway.
Horm Metab Res.
2004;
36
519-525
-
9
Wassermann G F, Loss E S.
Testosterone action on the Sertoli cell membrane: a KIR6.x channel related effect.
Curr Pharm Design.
2004;
10
2649-2656
-
10
Lacy P E, Kostianovsky M.
Method for the isolation of intact islets of Langerhans from the rat pancreas.
Diabetes.
1967;
16
35-39
-
11
Metz S A.
Ether-linked lysophospholipids initiate insulin secretion. Lysophospholipids may mediate effects of phospholipase A2 activation on hormone release.
Diabetes.
1986;
35
808-817
-
12
Lernmark A.
The preparation of, and studies on, free cell suspensions from mouse pancreatic islets.
Diabetologia.
1974;
10
431-438
-
13
Barja-Fidalgo C, Guimaraes J A, Carlini C R.
Canatoxin, a plant protein, induces insulin release from isolated pancreatic islets.
Endocrinology.
1991;
128
675-679
-
14
Batra S, Sjogren C.
Effect of estrogen treatment on calcium uptake by the rat uterine smoth muscle.
Life Sci.
1983;
32
315-319
-
15
Bradford M M.
A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding.
Anal Biochem.
1976;
72
248-254
-
16
Lieberherr M, Grosse B.
Androgens increase intracellular calcium concentration and inositol 1,4,5-triphosphate and diacylglycerol formation via pertussis toxin-sensitive G-protein.
J Biol Chem.
1994;
269
7217-7223
-
17
Haffner S M, Shaten J, Stern M P, Smith G D, Kuller L.
Low levels of sex hormone-binding globulin and testosterone predict the development of non-insulin-dependent diabetes mellitus in men.
Am J Epidemiol.
1996;
143
889-897
-
18
Barrett-Connor E, Khaw K T, Yen S SC.
Endogenous sex hormone levels in older adult men with diabetes mellitus.
Am J Epidemiol.
1990;
132
895-901
-
19
Barrett-Connor E.
Lower endogenous androgen levels and dyslipidemia in men with non-insulin-dependent diabetes mellitus.
Ann Intern Med.
1992;
117
807-811
-
20
Abate N, Haffner S M, Garg A, Peshock R M, Grundy S M.
Sex steroid hormones, upper body obesity, and insulin resistance.
J Clin Endocrinol Metab.
2002;
87
4522-4527
-
21
Hakola K, Pierroz D D, Aebi A, Vuagnat B AM, Aubert M L, Huhtaniemi I.
Dose and time relationships of intravenously injected rat recombinant luteinizing hormone and testicular testosterone secretion in the male rat.
Biol Reprod.
1998;
59
338-343
-
22
Bartke A, Dalterio S.
Evidence for episodic secretion of testosterone in laboratory mice.
Steroids.
1995;
26
749-756
-
23
Coquelin A, Desjardins C.
Luteinizing hormone and testosterone secretion in young and old male mice.
Am J Physiol.
1982;
243
E257-E263
G. F. Wassermann
Departamento de Fisiologia · ICBS · UFRGS
Rua Sarmento Leite, 500 · CEP 90050-170 Porto Alegre, RS · Brazil
Phone: +55 (51) 33 16 33 02
Fax: +55 (51) 33 16 33 02
Email: gwass@ufrgs.br
