The Possible Role of Prolactin in the Regulation of Nesting Behaviour and the Secretion of Luteinizing Hormone in Broody Bantams

Abstract

The time spent each day on the nest and the rate of formation of the brood patch before the onset of incubation were measured in bantams (Gallus domesticus) and related to changes in the concentrations of plasma LH and prolactin. The hens spent progressively more time on the nest in the 5 days before the onset of incubation so that by the first day of incubation they were spending more than 90% of their time in this way. The concentration of plasma prolactin increased while that of LH fell on successive days before the onset of incubation: the increase in plasma prolactin preceded the fall in plasma LH by 2 days. The formation of the brood patch closely followed the increase in the concentration of plasma prolactin. In four out of five bantams the increase in nesting behavior was preceded by an increase in the secretion of prolactin. An injection of chicken prolactin antiserum into bantams incubating eggs resulted in a significant (P less than 0.05) increase in the plasma concentration of LH. The observations suggest that, in the bantam, the onset of incubation is initiated by an increase in the secretion of prolactin which also suppresses the secretion of LH.

Endocronological and behavioural effects of p-chlorophenylalanine (PCPA) oral administration to broody turkey hens (Meleagris gallopavo)

“…Subsequently, by the end of the trial, the differences between the plasma prolactin concentrations of these birds and those of the photorefractory hens were no longer significant (P > 0.05) (Burke et al, 1981;Proudman and Opel, 1981;Lea et al, 1981;Bacon et al, 1983;Zadworny, 1985 . The data presented in Tables I and II do not support this hypothesis since the change in feed and water intake that followed the disruption of broodiness occured when plasma prolactin was at lower levels.…”

The Role of Prolactin in the Regulation of Clutch Size and Onset of Incubation Behavior in the American Kestrel

“…The onset of incubation in species producing clutch sizes of more than two eggs is generally associated with increased plasma prolactin (Lea, Dods, Sharp, and Chadwick, 1981;Goldsmith, 1983;El Halawani, Fehhrer, Hargis, and Porter, 1988;Buntin, 1996;Sharp, 1997b). Immunization against prolactin or the prolac-tin-releasing-factor vasoactive intestinal peptide (Sharp, Dawson, and Lea, 1998) inhibits incubation (Crisó stomo, Guémené, Garreau-Mills, and Zadworny, 1997;Sharp, 1997a;Crisó stomo, Guémené, Garreau-Mills, Morvan, and Zadworny, 1998).…”

“…Treatment of females with exogenous prolactin induces incubation if it is preceded by nesting behavior, which is dependent on increased plasma progesterone and estradiol 17-␤ (El Halawani, Silsby, Behnke, and Fehrer, 1986;Sharp, 1997b). Thus, the transformation of nesting behavior to incubation behavior seems largely regulated by rising plasma prolactin levels during and immediately following laying (Lea et al, 1981).…”

“…Cessation of egg laying is associated with increased concentrations of plasma prolactin (Etches, Garbutt, and Middleton, 1979;Burke and Dennison, 1980;Lea et al, 1981;Bluhm, Phillips, and Burke, 1983;Hall and Goldsmith, 1983;Silverin and Goldsmith, 1983), and in turkeys and domestic fowl (Sharp, Macnamee, Sterling, Lea, and Pedersen, 1988), administration of exogenous prolactin suppresses plasma gonadotropins necessary for egg production. However, there is additional evidence that the suppression of gonadotropin secretion in incubating birds also involves a mechanism independent of increased prolactin secretion (Sharp et al, 1988;Lea and Sharp, 1989;Sharp, Sterling, Talbot, and Huskisson, 1989;Lea, Richard-Yris, and Sharp, 1996).…”

Specific Binding of Vasoactive Intestinal Peptide Receptor in Cephalic and Caudal Lobes of Anterior Pituitary of Incubating and Laying Hens and Roosters.

“…The specific binding in the cephalic lobe of the incubating hens was also greater than that in the same lobe of the laying hens. Since VIP stimulates the secretion of prolactin (SHARP et al, 1989;EL HALAWANI et al, 1990;TALBOT et al, 1991), the greater binding in the cephalic lobe in the incubating hens may be concerned in the incubation behavior of the hens expressed by an increased secretion of prolactin (SHARP et al, 1979;BEDRAK et al, 1981;LEA et al, 1981LEA et al, , 1982 by the action of VIP through its receptor bindings. The specific binding in the cephalic lobe of the laying hens was greater than that in the same lobe of the roosters.…”