Figure 4.

Expression and activation of G proteins and 5-HT₁ receptor during H. trivolvis development. (A) (Eu)GTPγS binding assay demonstrates 5-HT-iduced activation of G_s, but not G_q protein in membrane preparations of H. trivolvis. Activation of G_q by FMRFamide was used as a positive control. (B) Western blot representing proteins from membrane preparations of H. trivolvis embryos at different developmental stages. The proteins were visualized with the antibodies against the 5-HT₁R, G_i- and G_s-proteins. (C-E) Quantification of protein expression performed by densitometry. Relative amounts of 5-HT₁R (C), G_i-protein (D), and G_s-protein (E) are shown at the stages 19, 23, and 25. Expression of 5-HT₁ receptor and G proteins undergoes changes during H. trivolvis development. Maximal expression of 5-HT₁R and corresponding G_i-protein was obtained at the beginning of metamorphosis (st 23), while G_s-protein was maximally expressed at the premetamorphic stage (st 19) and gradually decreases by the metamorphic stage (st 25). Each value represents the mean ± s.d. (n = 4). A statistically significant difference between values is noted (**, p <0.01, ***, p <0.001).