Seasonal changes in plasma retinol-binding holoprotein concentration in japanese quail (Conturnix coturnix japonica)

Abstract

I. Seasonal changes in retinol-binding holoprotein (holoRBP) concentration in plasma of groups of male and female Japanese quail (Coturnir corurnix juponicu) were examined over 18 months. 2.In Expts I and z the birds were maintained under natural lighting conditions and in Expt 3 under artificial-light photoperiods corresponding to the changing daylength at 56" N latitude. All groups were at 18-20" and received Superlayers' (Rank Hovis McDougall) pellet diet.3. The mean plasma holoRBP concentration in all groups changed in an annual cycle with minimal values in September-October and maximal values in February-April, when daylength or light photoperiod increased to more than 10 h.4. The group mean values in the female cycle change 2-to 3-fold from 5~1 0 0 pg/ml in late summer to 220-280pg/ml in the spring, whereas in the male the range is only 1'3-1'5 times, from 140-170 to 186250 ,ug/ml. 5.In the female the rate of egg laying was maximal in April-May and lowest in November-December.6. The spring increase in plasma holoRBP reflects the increased vitamin A requirement of birds for reproduction and it is presumably under hormonal control. The wider amplitude in the female cycle compared with the male probably arises from the additional demand for the transfer of vitamin A into the eggs and hence the need for a higher initial secretion rate from the female liver to meet it.Retinol-binding protein (RBP) is the specific carrier protein for vitamin A in plasma. It is necessary for the distribution of the vitamin to target tissues such as the eye, epithelial tissues and the gonads. Retinol is bound to the protein (approximately 21000 daltons) in a I : I complex in the human (Kanai et al. 1968) and in all other animal species so far examined including the chick (Abe et al. 1975). This material is called holoRBP to distinguish it from the uncomplexed or unsaturated apoRBP. It has been established previously that the absence of vitamin A for completion of the synthesis of the bimolecular complex in the liver inhibits the release of the protein into the bloodstream by as much as 70 % (Muto et al. 1972). Alternatively, deficiency of good-quality protein in the diet of an otherwise vitamin A-replete subject reduces the pool of some essential amino acids for protein biosynthesis in the liver and lowers the plasma RBP concentration by as much as 3 0~ below control values (Muhilal & Glover, 1974). Thus the plasma level of RBP can change as a consequence of nutritional deficiencies. However, in the normal seasonal breeding animal like the sheep, replete with vitamin A and protein, the concentration of holoRBP undergoes annual cyclic changes from a minimum of 25 pg/ml in the summer to a maximum of ~oopg/ml plasma in the autumn and then gradually regresses in the spring to the summer value (Glover et al. 1976).The autumnal surge in RBP concentration occurs in both sexes with decreasing daylength which has also long been known (Yeats, 1949) to effect changes in the sexual development of sheep. This relationship between RBP concentra...

Effect of Artificial Photoperiods on Plasma Thyroxine-Binding Prealbumin and Retinol-Binding Protein in Japanese Quail

“…Similarly, the onset of egg laying and cloacal gland development were also delayed by the equivalent of 2 months of solar-dial clock time. The mean maximum mid-summer levels of holoRBP were lower than those observed in birds on the annual cycle (Heaf & Glover, 1979;Glover et al 1980) and in males the expected peak in mid-summer was reduced to a level which was only just significant. Nevertheless, the changes in RBP and TBPA over the cycle were sufficient to produce a marked effect on the ratio of the two proteins as illustrated in Fig.…”

“…In this connection, it was interesting to note that in Japanese quail, where the variations in TBPA and holoRBP were studied over 1 -5 annual cycles (El-Sayed et al 1980;Glover et al 1980), that egg laying commenced in late February in the first cycle whereas in the second cycle it did not occur until late March. Both these events followed the times which the molar ratio of TBPA : RBP changed to 1-0 by approximately the same delay of 10-12 days in each cycle, indicating a closer link between gonadal development (for egg laying) and TBPA : holoRBP ratio than between a particular photoperiod alone.…”

“…The concentrations of these carrier proteins in plasma influence the rates at which their respective ligands are delivered to the various target tissues. It has been demonstrated that the concentration of RBP increases in the plasma of Japanese quail in the spring and declines in the late summer in response to the changing photoperiod during the annual cycle (Heaf & Glover, 1979;Glover, Heaf & Large, 1980). Thus an increased supply of vitamin A is made available for growth of the male and female reproductive tissues and for egg laying in the female.…”

Circannual Changes in Plasma Concentrations of Immunoreactive Retinol-Binding Protein and Luteinizing Hormone in Male and Female Japanese Quail

“…In domestic fowl, reproduction continues normally up to the point of egg-laying but the embryo fails to develop beyond day 2 unless vitamin A derivatives, of which the most potent is retinol, are injected into the eggs before incubation (Thompson, Howell, Pitt & McLaughlin, 1969). More recently it has been shown that the concentration of plasma retinol-binding holoprotein (holoRBP, protein with retinol bound) undergoes a seasonal increase in autumn in sheep (Glover, Jay, Kershaw & Reilly, 1976) and in spring in Japanese quail (Coturnix coturnix japónica; Glover & Large, 1977;Glover, Large & Heaf, 1980). In both species a two-to threefold rise in plasma holoRBP concentration has been observed at the beginning ofthe sexually active part of the annual cycle of gonadal growth and regression, followed by a steep fall about 2 months later.…”

Synthesis, analysis and characterization of deuterated analogues of vitamin A

“…Plasma RBP levels, and therefore retlnol concentrations, are known to increase with increased levels of steroid sex-hormones as found In the natural cycles of females of several species. Including humans (22)(23)(24)(25)(26). This mechanism Is proposed to operate through Increased hepatic synthesis of RBP and subsequent mobilization (26).…”