Effect of starvation on insulin production and insulin binding in Tetrahymena

Effect of glucose on the insulin production and insulin binding of Tetrahymena

As the unicellular ciliate, Tetrahymena has insulin receptors and produces insulin itself, which can regulate its glucose metabolism and other cell functions, in the present experiments the feed-back, the effect of glucose on the insulin binding and insulin production was studied. The cells were kept partly in tryptone-yeast medium, partly in Losina salt solution. The duration of treatment (in 0.1, 1.0, 10.0 mg/ml glucose) in the binding study was 10 min, in the hormone production study 30 min. FITC-insulin binding was significantly decreased only by 0.1 mg/ml glucose treatment in medium and by 10 mg/ml glucose in salt. The insulin production was significantly lower only in cells treated with 10 mg/ml glucose in medium. The insulin binding in salt was always higher and the insulin production always lower, than in medium. Earlier results demonstrated that the hormonal system (presence of hormones, receptors and signal pathways) of higher ranked animals can be deduced to a unicellular level, however, the feed-back mechanism is not really present here, only the traces can be observed in these protozoa.

Thyrotropin (TSH) regulates triiodothyronine (T3) production in the unicellular Tetrahymena

The aim of the experiments was to study the regulation of triiodothyronine (T3) production in the unicellular Tetrahymena. Untreated and troph-hormone treated specimen were prepared and in different timepoints T3 content was measured and compared by immunocytochemical flow cytometry. 0.1 or 0.001 IU TSH in tryptone-yeast medium stimulated T3 synthesis at 10, 20, 30 min, but does not stimulate after 1 h. The overlapping gonadotropic hormone (GTH) also did it, however only at 10 min. In Losina salt solution (physiological for Tetrahymena) the effect was weaker, however outer amino acid source was not absolutely needed for the production of the hormone. The results show that the TSH regulation of thyroid hormone synthesis (storage, secretion) and troph-hormone overlap can be deduced to a unicellular level. This may allow the hypothesis that the endocrine mechanisms proved at a low level of phylogeny are preserved for the higher ranked organisms.