TY - JOUR
T1 - Osmoregulatory effects of hypophysectomy and homologous prolactin replacement in hybrid striped bass.
AU - Jackson, Leslie F
AU - McCormick, Stephen D
AU - Madsen, Steffen S
AU - Swanson, Penny
AU - Sullivan, Craig V
PY - 2005/2/1
Y1 - 2005/2/1
N2 - The effects of ovine prolactin (oPRL) and striped bass prolactin (sbPRL; Morone saxatilis) on plasma osmolality, electrolyte balance, and gill Na+,K+-ATPase activity were investigated in hypophysectomized (Hx), freshwater (FW)-acclimated, hybrid striped bass (M. saxatilis x Morone chrysops). They were kept in dilute (isoosmotic) seawater for about 10 days after surgery. Seven days after transfer to FW, Hx fish had lower plasma osmolality and lower levels of Na+, Cl-, and Ca2+ than sham-operated and intact fish. Fish were injected four times with oPRL (1, 5, or 20 microg/g body mass), sbPRL (10 or 100 ng/g), or hormone vehicle (0.9% NaCl) at 48-h intervals (days 0, 2, 4, and 6) in FW and then sampled for blood plasma 24 h after the fourth injection (day 7). In Hx fish, oPRL (5 and 20 microg/g) and sbPRL (10 and 100 ng/g) were effective in maintaining plasma osmolality and levels of Na+, Cl-, and Ca2+ above values seen in saline-injected controls. Hypophysectomy did not affect branchial Na+,K+-ATPase activity, but enzyme activity was significantly reduced in Hx fish receiving oPRL (20 mug/g) or sbPRL (10 or 100 ng/g). These results indicate that PRL acts to maintain plasma osmotic and ionic balance in FW-adapted hybrid striped bass, and that this may involve downregulation of branchial Na+,K+-ATPase activity.
AB - The effects of ovine prolactin (oPRL) and striped bass prolactin (sbPRL; Morone saxatilis) on plasma osmolality, electrolyte balance, and gill Na+,K+-ATPase activity were investigated in hypophysectomized (Hx), freshwater (FW)-acclimated, hybrid striped bass (M. saxatilis x Morone chrysops). They were kept in dilute (isoosmotic) seawater for about 10 days after surgery. Seven days after transfer to FW, Hx fish had lower plasma osmolality and lower levels of Na+, Cl-, and Ca2+ than sham-operated and intact fish. Fish were injected four times with oPRL (1, 5, or 20 microg/g body mass), sbPRL (10 or 100 ng/g), or hormone vehicle (0.9% NaCl) at 48-h intervals (days 0, 2, 4, and 6) in FW and then sampled for blood plasma 24 h after the fourth injection (day 7). In Hx fish, oPRL (5 and 20 microg/g) and sbPRL (10 and 100 ng/g) were effective in maintaining plasma osmolality and levels of Na+, Cl-, and Ca2+ above values seen in saline-injected controls. Hypophysectomy did not affect branchial Na+,K+-ATPase activity, but enzyme activity was significantly reduced in Hx fish receiving oPRL (20 mug/g) or sbPRL (10 or 100 ng/g). These results indicate that PRL acts to maintain plasma osmotic and ionic balance in FW-adapted hybrid striped bass, and that this may involve downregulation of branchial Na+,K+-ATPase activity.
KW - Bass
KW - Hypophysectomy
KW - Prolactin
KW - Gill
KW - Electrolytes
KW - Water-Electrolyte Balance
KW - Osmoregulation
U2 - 10.1016/j.cbpc.2004.10.004
DO - 10.1016/j.cbpc.2004.10.004
M3 - Journal article
C2 - 15649768
SN - 1096-4959
VL - 140
SP - 211
EP - 218
JO - Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology
JF - Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology
IS - 2
ER -