Abstract
Abstract Effects of cortisol on rat and rabbit lymphoid cells incubated in vitro have been studied. Cells either obtained from cortisol-treated rats or exposed to cortisol in vitro at concentrations of 1 x 10-8 to 1 x 10-5 m showed a diminished degree of incorporation of radioactive precursors into RNA, DNA, and protein. The onset of the effects of cortisol added in vitro was gradual and the effects increased in magnitude with time. Removal of steroid from the cell suspension did not alter the degree of inhibition that already existed. However, with further incubation after removal of steroid there was no further progression or diminution of the inhibitory effect. Cells were not affected when incubated with steroid at 2°. The gradual onset of the effects of cortisol added in vitro was not eliminated by increasing steroid concentration or by varying of several other parameters. In studies with the use of thymocytes with prelabeled RNA, DNA, or protein, incubation with cortisol did not enhance degradation or produce leakage from the cell of the macromolecules. The relative order of sensitivity of lymphoid cells to cortisol added in vitro was as follows: rat thymocytes, rabbit mesenteric node cells, rat mesenteric node cells, and rabbit thymocytes. The steroid inhibitory effects on rabbit node cells also occurred when cells were stimulated in vitro by a thymic fraction containing thymosin, a lymphocytopoietic factor. Thymocytes incubated in vitro after exposure to cortisol in vivo or in vitro exhibited decreased incorporation of precursors into the trichloracetic acid-soluble as well as the trichloracetic acid-insoluble fraction. Medium requirements and the time course for effects on both fractions were the same. Cortisol added in vitro also inhibited α-aminoisobutyric acid and 1-aminocyclopentane-1-carboxylic acid uptake. The data presented indicate a steroid influence on amino acid transport as well as on intracellular accumulation of phosphorylated nucleosides and guanine.
Highlights
Cells incubated with cortisol for periods of 1 to 2+ hours, freed of st,eroid by washing at either 2” or 37”, and transferred to fresh medium showed the same degree of inhibition as that present at the time the steroid was removed
In studies with eortisolJH, washing of thymocytes at 37” as described in Table I was found to remove all detectable cortisol from the cells.[3]
Similar data were obtained when thymocytcs were exposed to cortisol in vivo and removed from the influence of the hormone and incubated in vitro for an additional 3 hours (Table I)
Summary
Effects of cortisol on rat and rabbit lymphoid cells incubated in vitro have been studied. Cells incubated with cortisol for periods of 1 to 2+ hours, freed of st,eroid by washing at either 2” or 37”, and transferred to fresh medium showed the same degree of inhibition as that present at the time the steroid was removed. In studies with eortisolJH, washing of thymocytes at 37” as described in Table I was found to remove all detectable cortisol from the cells.[3] Similar data were obtained when thymocytcs were exposed to cortisol in vivo and removed from the influence of the hormone and incubated in vitro for an additional 3 hours (Table I). After the 30-min eqGlibration period, separate portious of the cell sllspensions were incubated for ali additional period of time in vitro, tither with or withoclt 1 X 10-F M cortisol present, prior to pulse labeling for 1 hour as described above. The incubations in vitro were irrterrllpted at the indicated time points by a washing proccdrlre to remove steroid
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
