114
IVAN (4OODRODY
The rnont crit’ical study of this problem has been carried out by
Dodd and Dodd (1966) who prepared an extract from the neural
complexes of about 8000 specimens of Gionu intestinalis which was
assayed for oxytocin, vttsopressin, ADH and MSH. In tctsts for oxytooin
both guineii-pig and nit, utwun proparatioil8 wwe u ~ e d for ri~stty snd
showed that a smooth musclc coiitrltctant is present in the neiiral complex. Assays on guinea-pig uterus suggested an activity equivalent t o
30 I m U of oxytocin, while rat uterus preparations suggested an activity
equivalent to only 0-4 ImU. This might be due to the presence of two
different active substances acting on the different assay preparations.
Furthermore extracts of female gonad, male gonad plus stomach, and
branchial region of the ascidian had it similar action on rat uterus, but
a
b
C
d
e
f
4
FIQ. 31. Tho oxwtencw of IL smo1)th miiwltr aontractibnt in tsho noural complex and
branrhid rogion of (‘iowa illiirtruttrtl hy tbo offoctH of oxtracts on the guinea pig
iitorii*. IL eiitL b, itijoctionx 01‘ 60 lmlJ I’itocin; c, (1 and f, injection of 30 TmU
l’itociii : o, injoction of 44) mg of IUI tjxtrclet of neiiral oomplox; g. injection of 4.0 mg
of ILII oxtract of tho 1)rartehtal HILC. (JCotlrawii frorn Dodd and I h d d , 1966.)
were slightly less potent-approximtttely 50%, 50% and 70% renpectively of the potency of neural complex (Fig. 31). Although a smooth
muscle contractant i8 present in the ascidian neural complex, it i R
probably not oxytocin itself. Dodd and Dodd give the following reasons
for concluding that it is different. (a) The active principle has a much
shorter latent period of action than oxytocin (see Fig. 32). (b) It
survives storago at pH 7 in the cold for several months, and exposure to
air at pH 3.8 at room temperature for a year, procedures which destroy
posterior pituitary activity. (c) I t is resistant to boiling with caustic
soda and incubation with sodium thioglycollate at concentrations which
destroy posttxior pituitary oxytocin. (d) It, is resistant to ultraviolet
light.
It seems therefore that the active principle in ascidian neural complex and causing smooth muscle contraction is different from oxytocin
IVAN (4OODRODY
The rnont crit’ical study of this problem has been carried out by
Dodd and Dodd (1966) who prepared an extract from the neural
complexes of about 8000 specimens of Gionu intestinalis which was
assayed for oxytocin, vttsopressin, ADH and MSH. In tctsts for oxytooin
both guineii-pig and nit, utwun proparatioil8 wwe u ~ e d for ri~stty snd
showed that a smooth musclc coiitrltctant is present in the neiiral complex. Assays on guinea-pig uterus suggested an activity equivalent t o
30 I m U of oxytocin, while rat uterus preparations suggested an activity
equivalent to only 0-4 ImU. This might be due to the presence of two
different active substances acting on the different assay preparations.
Furthermore extracts of female gonad, male gonad plus stomach, and
branchial region of the ascidian had it similar action on rat uterus, but
a
b
C
d
e
f
4
FIQ. 31. Tho oxwtencw of IL smo1)th miiwltr aontractibnt in tsho noural complex and
branrhid rogion of (‘iowa illiirtruttrtl hy tbo offoctH of oxtracts on the guinea pig
iitorii*. IL eiitL b, itijoctionx 01‘ 60 lmlJ I’itocin; c, (1 and f, injection of 30 TmU
l’itociii : o, injoction of 44) mg of IUI tjxtrclet of neiiral oomplox; g. injection of 4.0 mg
of ILII oxtract of tho 1)rartehtal HILC. (JCotlrawii frorn Dodd and I h d d , 1966.)
were slightly less potent-approximtttely 50%, 50% and 70% renpectively of the potency of neural complex (Fig. 31). Although a smooth
muscle contractant i8 present in the ascidian neural complex, it i R
probably not oxytocin itself. Dodd and Dodd give the following reasons
for concluding that it is different. (a) The active principle has a much
shorter latent period of action than oxytocin (see Fig. 32). (b) It
survives storago at pH 7 in the cold for several months, and exposure to
air at pH 3.8 at room temperature for a year, procedures which destroy
posterior pituitary activity. (c) I t is resistant to boiling with caustic
soda and incubation with sodium thioglycollate at concentrations which
destroy posttxior pituitary oxytocin. (d) It, is resistant to ultraviolet
light.
It seems therefore that the active principle in ascidian neural complex and causing smooth muscle contraction is different from oxytocin