Plasma prolactin levels during smolting in Atlantic salmon, Salmo salar

Abstract

To obtain more information on a possible involvement of prolactin during Parr-smolt transformation of Atlantic salmon, Salmo salar, parr and smolt populations of the same age were sampled from February to June. A clear separation of the two populations was observed according to their size and gill (Na+-K+ ) -ATPase activity. Comparison of plasma prolactin (PRL) levels between these two populations indicated a significant decrease from May to early July in smolts whereas, in Parr, a steady increase was observed. Die1 variations in plasma PRL levels at three different dates were also studied in fish undergoing smolting. Sampling fish over a 24-h period on 11 March, 5 May and 15 July did not indicate the presence of a die1 rhythm in PRL release. These data support the hypothesis that the PRL decrease is associated with smolting in Atlantic salmon and that such a decrease cannot be explained by a change in die1 rhythm of plasma PRL levels.

Melatonin and osmoregulation in fish: A focus on Atlantic salmon Salmo salar smoltification

“…11 Conversely, PRL promotes ion uptake and is inhibitory to salt secretion. 58,59 PRL, the levels of which are low during the smoltification process, 55,60 inhibits GH-and cortisol-induced elevations of gill NKA transcription and activity, probably by decreasing the capacity of the gills to respond to IGF-I.…”

Melatonin and osmoregulation in fish: A focus on Atlantic salmon Salmo salar smoltification

“…11 Conversely, PRL promotes ion uptake and is inhibitory to salt secretion. 58,59 PRL, the levels of which are low during the smoltification process, 55,60 inhibits GH-and cortisol-induced elevations of gill NKA transcription and activity, probably by decreasing the capacity of the gills to respond to IGF-I.…”

Morphological skin colour changes in teleosts

“…In fish, PRL is primarily involved in freshwater osmoregulation by promoting the development of freshwater chloride cells and inhibiting the formation of seawater chloride cells (McCormick 2001). Its gene expression, synthesis and secretion are often recognized to be stimulated by low environmental osmolality (Prunet and Boeuf 1989; Kaneko and Hirano 1993; Taniyama et al. 1999; Power 2005; Sakamoto et al.…”

“…In fish, PRL is primarily involved in freshwater osmoregulation by promoting the development of freshwater chloride cells and inhibiting the formation of seawater chloride cells (McCormick 2001). Its gene expression, synthesis and secretion are often recognized to be stimulated by low environmental osmolality (Prunet and Boeuf 1989;Kaneko and Hirano 1993;Taniyama et al 1999;Power 2005;Sakamoto et al 2005). However, in sockeye salmon, gill ATPase activity and chloride cell number decreased during the spawning migration before freshwater entry and in maturing fish held in seawater, thus ahead of any osmotic cue (Shrimpton et al 2005), which might have occurred from interactions of PRL with the BPG axis.…”

Osmoregulatory ability and stress responses during freshwater adaptation of black porgy (Acanthopagrus schlegeli) treated with exogenous prolactin

“…Hyperosmoregulatory role of PRL has been studied in several teleosts. Plasma PRL level was found to decrease in many salmonids when they were transferred from FW to seawater (SW) (Prunet & Boeuf 1989;Young, Bjornsson, Prunet, Lin & Bern 1989;Yada, Takahashi & Hirano 1991), however, tilapia (Oreochromis mossambicus) showed increased levels of plasma PRL when transferred from SW to FW (Yada, Hirano & Grau 1994;Shepherd, Sakamoto, Hyodo, Ball, Nishioka, Bern & Grau 1999). In gilthead seabream (Sparus aurata) PRL-secreting cells had significantly increased after transfer from SW to FW (Mancera, Perez-Figares & Fernandez-Llebrez 1993).…”

Melatonin and osmoregulation in fish: A focus on Atlantic salmon Salmo salar smoltification

“…11 Conversely, PRL promotes ion uptake and is inhibitory to salt secretion. 58,59 PRL, the levels of which are low during the smoltification process, 55,60 inhibits GH-and cortisol-induced elevations of gill NKA transcription and activity, probably by decreasing the capacity of the gills to respond to IGF-I.…”

Morphological skin colour changes in teleosts

“…In fish, PRL is primarily involved in freshwater osmoregulation by promoting the development of freshwater chloride cells and inhibiting the formation of seawater chloride cells (McCormick 2001). Its gene expression, synthesis and secretion are often recognized to be stimulated by low environmental osmolality (Prunet and Boeuf 1989; Kaneko and Hirano 1993; Taniyama et al. 1999; Power 2005; Sakamoto et al.…”

“…In fish, PRL is primarily involved in freshwater osmoregulation by promoting the development of freshwater chloride cells and inhibiting the formation of seawater chloride cells (McCormick 2001). Its gene expression, synthesis and secretion are often recognized to be stimulated by low environmental osmolality (Prunet and Boeuf 1989;Kaneko and Hirano 1993;Taniyama et al 1999;Power 2005;Sakamoto et al 2005). However, in sockeye salmon, gill ATPase activity and chloride cell number decreased during the spawning migration before freshwater entry and in maturing fish held in seawater, thus ahead of any osmotic cue (Shrimpton et al 2005), which might have occurred from interactions of PRL with the BPG axis.…”

Osmoregulatory ability and stress responses during freshwater adaptation of black porgy (Acanthopagrus schlegeli) treated with exogenous prolactin

“…Hyperosmoregulatory role of PRL has been studied in several teleosts. Plasma PRL level was found to decrease in many salmonids when they were transferred from FW to seawater (SW) (Prunet & Boeuf 1989;Young, Bjornsson, Prunet, Lin & Bern 1989;Yada, Takahashi & Hirano 1991), however, tilapia (Oreochromis mossambicus) showed increased levels of plasma PRL when transferred from SW to FW (Yada, Hirano & Grau 1994;Shepherd, Sakamoto, Hyodo, Ball, Nishioka, Bern & Grau 1999). In gilthead seabream (Sparus aurata) PRL-secreting cells had significantly increased after transfer from SW to FW (Mancera, Perez-Figares & Fernandez-Llebrez 1993).…”

Melatonin and osmoregulation in fish: A focus on Atlantic salmon Salmo salar smoltification

“…11 Conversely, PRL promotes ion uptake and is inhibitory to salt secretion. 58,59 PRL, the levels of which are low during the smoltification process, 55,60 inhibits GH-and cortisol-induced elevations of gill NKA transcription and activity, probably by decreasing the capacity of the gills to respond to IGF-I.…”

Morphological skin colour changes in teleosts

“…In fish, PRL is primarily involved in freshwater osmoregulation by promoting the development of freshwater chloride cells and inhibiting the formation of seawater chloride cells (McCormick 2001). Its gene expression, synthesis and secretion are often recognized to be stimulated by low environmental osmolality (Prunet and Boeuf 1989; Kaneko and Hirano 1993; Taniyama et al. 1999; Power 2005; Sakamoto et al.…”

“…In fish, PRL is primarily involved in freshwater osmoregulation by promoting the development of freshwater chloride cells and inhibiting the formation of seawater chloride cells (McCormick 2001). Its gene expression, synthesis and secretion are often recognized to be stimulated by low environmental osmolality (Prunet and Boeuf 1989;Kaneko and Hirano 1993;Taniyama et al 1999;Power 2005;Sakamoto et al 2005). However, in sockeye salmon, gill ATPase activity and chloride cell number decreased during the spawning migration before freshwater entry and in maturing fish held in seawater, thus ahead of any osmotic cue (Shrimpton et al 2005), which might have occurred from interactions of PRL with the BPG axis.…”

Osmoregulatory ability and stress responses during freshwater adaptation of black porgy (Acanthopagrus schlegeli) treated with exogenous prolactin

“…Hyperosmoregulatory role of PRL has been studied in several teleosts. Plasma PRL level was found to decrease in many salmonids when they were transferred from FW to seawater (SW) (Prunet & Boeuf 1989;Young, Bjornsson, Prunet, Lin & Bern 1989;Yada, Takahashi & Hirano 1991), however, tilapia (Oreochromis mossambicus) showed increased levels of plasma PRL when transferred from SW to FW (Yada, Hirano & Grau 1994;Shepherd, Sakamoto, Hyodo, Ball, Nishioka, Bern & Grau 1999). In gilthead seabream (Sparus aurata) PRL-secreting cells had significantly increased after transfer from SW to FW (Mancera, Perez-Figares & Fernandez-Llebrez 1993).…”