The response of the pituitary gland to luteinizing hormone-releasing hormone in broody bantams.
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Animals↗
Biomedical subjects
R W Lea
Publications and source records attributed to R W Lea.
Lack of a relationship between concentrations of plasma luteinising hormone, thyroxine and prolactin at nine week's of age and subsequent egg production in the domestic hen.
1. The concentrations of plasma luteinising hormone (LH), thyroxine and prolactin were measured in about 200 birds from each of two homogenous strains of White Leghorn hens at 9 weeks of age and related to subsequent egg production. 2. Within each strain, no relationships were found in individual birds between the concentrations of the plasma hormones and subsequent egg production after 90, 180 and 270 d of laying. 3. Single measurements of plasma LH, thyroxine or prolactin before the onset of lay do not appear to be useful criteria for the selection of egg-laying strains.
Animals↗
Concentrations of plasma luteinising hormone, prolactin, progesterone and androgens during the ovulatory cycle of the turkey.
1. Changes in the concentrations of plasma luteinising hormone (LH), prolactin, androgen and progesterone were measured during the ovulatory cycle of the turkey. 2. Single pre-ovulatory peaks of plasma LH, androgen an progesterone were observed which took 8, 8 and 12 h respectively, to increase and return to base-line values. The concentration of plasma prolactin tended to be elevated between 6 h before and 6 h after the LH peak with the maximum values occurring after the peak. 3. The changes in the concentrations of plasma LH and progesterone were 3- and 7-fold respectively while 2-fold changes were observed in the concentrations of plasma androgen and prolactin. 4. The pre-ovulatory concentration of plasma progesterone and prolactin began to decrease 4 and 6 h respectively, after the pre-ovulatory peak of LH. 5. Ovulation and oviposition occurred 6 to 8 h and 36.10 +/- 0.57 h (SEM) (n = 11) respectively after the pre-ovulatory peak of LH. 6. In birds kept on 14 h light/d, pre-ovulatory peaks of LH were initiated only during a 10 to 11-h period starting within 2 h after the onset of darkness. 7. A comparison between these data and those from the fowl suggest that the egg is retained in the turkey's oviduct for about 3 to 4 h longer than in the fowl.
Androgens↗
The possible role of prolactin in the regulation of nesting behaviour and the secretion of luteinizing hormone in broody bantams.
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.
Animals↗
Effect of prolactin, in vivo and in vitro, upon heterophil phagocytic function in the ring dove (Streptopelia risoria).
The purpose of this study was to investigate the effects of prolactin, both in vitro and in vivo, upon heterophil phagocytic activity of the ring dove, Streptopelia risoria. In vitro incubation of heterophils with either 0.1 or 100 micrograms/mL of ovine prolactin for 2 h-significantly increased both latex bead phagocytosis and Nitroblue tetrazolium (NBT) reduction, an index of phagocytic metabolic activity. Ring doves given antigen demonstrated an increase in latex bead phagocytosis and NBT reduction. The greatest increase in both of these parameters was observed in those birds which possessed elevated plasma prolactin concentrations, either through exogenous administration or naturally through being in the later stages of incubation. These results suggest that during the incubation period of the avian breeding cycle there is an increase in phagocytic activity which is a direct consequence of the elevation shown by these birds in the concentration of plasma prolactin.
Animals↗
Mitogenic effect of naturally occurring elevated plasma prolactin on ring dove lymphocytes.
3H-thymidine incorporation into isolated ring dove lymphocytes in vitro was used as a measure of lymphocyte proliferation. Lymphocytes taken from doves with increased plasma concentrations of prolactin demonstrated significantly increased 3H-thymidine incorporation. In vitro incubation with mitogens significantly increased incorporation of 3H-thymidine into lymphocytes from non-breeding doves. However, similar treatment of lymphocytes taken from doves which had elevated levels of plasma prolactin failed to induce any further increase in the stimulation index. Antigen caused a significant increase in 3H-thymidine incorporation in non-breeding doves. Antigen administration also led to the production of specific antibodies. The titre of specific anti-human red blood cell (HRBC) agglutinins was greatest in those birds which also had elevated levels of plasma prolactin, reaching significance in the group of incubating doves with naturally occurring increased concentrations of plasma prolactin. The results presented here may be relevant to our understanding of the role of hormones such as prolactin on lymphocyte activation.
Analysis of Variance↗