Table 6.9 Ma ximal w ate r uptake by amphibians in jected w ith v arious neurohypophy sial
hormones. ( From data colle cted by MOREL and JARD, 1968)
Maximal w ater
retention g/100 g
initial BW
Hormone
Anu ra
X enopus laevis
0
Pitres sin, Pitocin
Arginine-vasotocin
Neobatrachus
10
Oxytocin
Leptodactylus
16
Pitressin , Pitocin
Discoglossus pictus
19
Arg inine-vasotocin
Pelobates cultripes
13
Arginine-vasotocin
Rana clamitans
14
Pirocin) Pitressin
Rana pipiens
14-19
Pi tocin ) Pi tressin
18
Pituitrin
Rana esculenta
12-24
Pitocin) Pitressin
AVT) AVP ) O xy )LVP
20
Arg inin e-va sotoc in
R ana temporaria
28
Pi tocin ) P itressin
Bufo bu]»
AVP ) AVT ) Oxy)LVP
18
Arg inin e-va sotoci n
40
Pirressin) Pito cin
Bufo caren s
22
Pirressin) Pitocin
Bufo regularis
22
P itressin j P itoc in
45
P itu itrin
Bufo americanus
45
Pir ressin) Pitocin
H yla hyla
53
Arginine-vasotocin
Urodela
N ecturus maculosus
4
Pituitrin
2
Arginine-vasotocin
Ambystoma tigrinum
6-8
Ar ginine-vasotocin
Triturus alpe stris
8
Arginine-vasotocin
Triturus cristatus
10
Arginine-vasotocin
Salamandra maculosa
10
Argin ine-vasotocin
or toad would onl y represent about 10% or the total quantity stored in the neuroh ypophysis. Such information strongly suggests that this peptide may have a
physiological role in influencing the water metabolism of some amphibians, but
does not show this un equi vocally .
Neurohypophysectomy has yielded some conflicting results about the role of
th e neurohypophysis. Removal of the neurohyp ophysial tissue is a difficult operation and the simpl est way of doing it is to remove the entire pituitary .
Thi s procedure also results in th~ loss of a num ber of adeno hypo ph ysial
hormones. A loss of th ese can result (in Rana pipiens) in an increa sed osmot ic per194