Determination of TGF-beta-like activity in the rat cerebrospinal fluid after exhaustive exercise using anti-TGF-beta IgG and the hydra bioassay

We have proposed the participation of transforming growth factor beta (TGF- beta) in fatigue from a study using tentacle ball formation (TBF) of hydra as a bioassay (14). Cerebrospinal fluid (CSF) from sedentary rats (Sed CSF) suppressed the S-methylglutathione (GSM)induced TBF of hydra more strongly than the CSF from fatigued rats (Fatg CSF), but the difference was nullifi ed by the treatment of Fatg CSF with anti-TGF-beta IgG. This suggested that TGF-beta in Fatg CSF participates in the GMS-induced TBF. TGF-beta overcom es the TBF-suppressing effect of corticotropin-releasing factor (CRF) added to the TGF-beta- containing solution. A linear relationship was observed b etween the minimum amount of anti-TGF-beta IgG necessary to nullify the TBF -suppressing effect of CRF and TGF-beta in a wide range of concentration. T his amount of anti-TGF-beta IgG; corresponds to the amount necessary to nul lify the effect of TGF-beta in the solution. By using this relationship, we quantitatively examined the TGF-beta like activity in the Fatg CSF, using the anti-TGF-beta IgG and the hydra bioassay. No TGF-beta activity was dete cted in the Sed CSF, whereas the amount of TGF-beta in the Fatg CSF was 1.3 8 pg/mL. These results also confirm that fatigue is related to an increase in TGF-beta in the brain.