Prolonged elevation of insulin content in the unicellular tetrahymena after insulin treatment: induction of insulin production or storage?

✍ Scribed by György Csaba; Annamária Gaál; Péter Kovács; György Simon; László Köhidai

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 501 KB
• Volume: 17
• Category: Article
• ISSN: 0263-6484
• DOI: 10.1002/(sici)1099-0844(199909)17:3<165::aid-cbf824>3.0.co;2-w

✦ Synopsis

In the unicellular organism, Tetrahymena, the ®rst encounter with an exogeneously given hormone results in hormonal imprinting. This causes an increase of the binding capacity of receptors and the production of the appropriate hormone in the progeny generations of the treated cell. In the present experiments the quantity (using radioimmunoassay) and localization (using confocal laser scanning microscopy) of the immunologically insulin-like material (hereafter insulin) were studied for 10 days after 4 h or 24 h 10 À6 M insulin treatment (hormonal imprinting). Forty-eight hours after both insulin treatments a high quantity of insulin was present in the cells. This value was also signi®cantly increased after 96 h. After 8 days the dierence to the control was signi®cant only in the 24 h treated group. Confocal microscopy (using antibody to pig insulin) localized insulin in the cell body. The oral ®eld contained extremely high quantities of the endogeneous hormone. Insulin treatment (after 48 and 96 h) caused an elevation of insulin content in general, and speci®c accumulation in the posterior sections of the cell, around the nucleus and in the periphery were observed. Ten days after both treatments only the peripheral region of the cell body and the ciliary row contained more insulin than the control. This means that after insulin treatment the quantity of insulin increases for a lengthy time period which is followed by the expression of insulin in the peripheral region. Insulin contained by Tetrahymena 48 h after imprinting stimulated glucose uptake of rat diaphragm.