Cellular basis for elevated prolactin secretion during incubation behavior in Bantam chickens: analysis by reverse hemolytic plaque assay

Abstract

Incubation behavior in birds is characterized by elevated serum prolactin (PRL) levels. The objective of this study was to determine the cellular basis for increased PRL secretion. Incubation behavior of Bantam hens was induced by allowing the hens to accumulate their eggs. In experiment 1, hens were allowed to accumulate their eggs in floor pens for 0, 2, 12, or 24 days (Day 0, Day 2, Day 12, and Day 24 hens, respectively). Anterior pituitaries were dissociated into individual cells with trypsin, and the resulting cells were then subjected to reverse hemolytic plaque assays for PRL. The percentage of PRL-secreting cells and serum PRL levels were higher in Day 24 hens than in the other groups (p < 0.05; n = 3 separate trials). In experiment 2, hens were allowed to accumulate their eggs for 2, 14, 18, or 24 days (Day 2, Day 14, Day 18, and Day 24 hens, respectively). The percentage of PRL-secreting cells and levels of serum PRL were greater in Day 18 and Day 24 hens than in Day 2 hens (p < 0.05; n = 4). Results from Day 14 hens were intermediate and different (p < 0.05) from those from both Day 2 and Day 18 groups. Data indicate that an increase in the proportion of PRL secretors occurred between 14 and 18 days after hens began to accumulate their eggs. The area of plaques formed by lactotrophs from Day 14 and Day 18 hens was also increased (p < 0.05). In experiment 3, hens were allowed to accumulate their eggs for 0 and 24 days (Day 0 and Day 24 hens, respectively). Their anterior pituitaries were dissected into cephalic, middle, and caudal regions, and the percentage of PRL cells were analyzed in each region separately. The percentage of PRL secretors was increased (p < 0.05) in Day 24 compared to Day 0 hens in both the cephalic and middle regions of the anterior pituitary but not in the caudal portion. We conclude that increased PRL secretion during incubation behavior involves the recruitment of additional pituitary cells into the PRL-secreting population and an increase in the capacity of these cells to secrete hormone (p < 0.05). Furthermore, this increase in PRL-secreting cells is localized to the cephalic and middle regions of the anterior pituitary.

Expression Profile of Prolactin Gene in White Leghorn Layer and Control Broiler

“…expression investigations on chicken, comparisons with pertinent studies are done in order to connect the current findings. The current results may be similar to those of Rangneker et al (1978) and Lopez et al (1996) who explained that during incubation, granules and cells in the cephalic lobe grow, which raises prolactin levels in the blood. Prolactin levels decreased after antiprolactin or neutralization treatments performed by Parvez et al (2017), and Dawod et al (2021), who also concluded that prolactin levels are high during the incubation period.…”

Changes in Pituitary Somatotroph and Lactotroph Distribution in Laying and Incubating Turkey Hens

“…Lactotroph hypertrophy suggests that there is an increase in PRL secretory capacity which also would contribute to the hyperprolactinemia. The proportion of PRL secretors were increased in the cephalic and middle region of the anterior pituitary of incubating bantam hens (Lopez et al, 1996). The lactotrophic recruitment and hypertrophy in incubating hens observed in this study would partly explain the greater pituitary PRL content and PRL mRNA abundance in incubating turkey hens (Wong et al, 1992) compared with that of laying hens.…”

Identification of Mammosomatotrophs in the Turkey Hen Pituitary: Increased Abundance during Hyperprolactinemia*

“…Results from our earlier studies as well as those of others (1) suggest that there is recruitment of PRL-producing cells in the pituitaries of vertebrate animals under certain physiological conditions. The hyperprolactinemia in incubating bantam chicken hens has been associated with an increase in pituitary PRL secretors (28). Similarly, PRL-containing cells were increased in the pregnant human pituitary, with a concomitant decrease in GHcontaining cells (29).…”