Chicken Luteinizing Hormone Research Articles

Two Avian Luteinizing Hormone Radioimmunoassay Procedures Compared by Measurement of Changes During the Ovulatory Cycle of Turkey and Broiler hens

Two radioimmunoassay (RIA) procedures for measuring avian luteinizing hormone (LH) were compared using divided aliquots of plasma samples collected during the ovulatory cycles of turkey and broiler breeder hens in three separate experiments. The RIA systems compared were the homologous turkey LH assay of Wentworth et al. (1976) and the homologous chicken LH assay of Follett et al. (1972). Both assays provided the same assessment of circulating LH changes. The preovulatory surge of LH was observed 6 hr before ovulation in turkeys and 4 hr before ovulation in chickens. In addition, both assays detected an increase in chicken LH after ovulation, followed by a gradual decline prior to the next preovulatory surge. The correlation between RIA were highly significant (P<.001) in each experiment.The crossreaction of purified ostrich LH, FSH, and TSH and of the α and β subunits of turkey LH was assessed in each assay system. Ostrich LH, FSH, and TSH crossreacted in the chicken LH assay in a dose-related manner: ostrich LH showed the highest activity. Only ostrich TSH produced a response in the turkey assay that was dose related. The α subunit, but not the β subunit, of turkey LH was quite potent in the chicken LH RIA, but neither subunit competed as well as the native hormone in the turkey RIA. Thus, the two LH antisera recognize different portions of the LH molecule. The chicken antiserum apparently recognizes a site on the α subunit that may be at least partially masked in the FSH and TSH molecules. The turkey antiserum recognizes a site on the native LH molecule that is altered when the subunits are separated.

Synthesis and biological activity of [D-Trp 6] chicken luteinizing hormone-releasing hormone

An agonist of chicken hypothalamic luteinizing hormone-releasing hormone (cLH-RH). [D-Trp 6] cLH-RH, was synthesized and tested for luteinizing hormone (LH)-releasing activity using dispersed chicken anterior pituitary cells, as well as for binding to rat anterior pituitary membrane receptors. cLH-RH and mammalian LH-RH (mLH-RH) gave identical dose-response curves in stimulating chicken LH release ( ED 50=1.6 and 1.8×10 −9 M respectively) and similar estimates of potency. The [D-Trp 6] analogs of cLH-RH and mLH-RH stimulated LH release at lower doses ( ED 50=7.0 and ∼7.0×10 −11 M respectively) and were approximately 20-fold more potent. In contrast to the activity in the chicken bioassay, cLH-RH bound to rat anterior pituitary membrane receptors with a much lower affinity than did mLH-RH and had a relative potency of 2%. [D-Trp 6] cLH-RH was approximately 100-fold more potent than cLH-RH in the rat receptor assay while [D-Trp 6] mLH-RH was 28-fold more active than mLH-RH. These data demonstrate that substitution of Gly 6 of LH-RH with D-Trp enhances the LH release from chicken pituitary cells to a similar extent to that observed in mammals, and indicate that the approaches used to produce active LH-RH analogs in mammals are likely to be applicable to birds.

Effects of Single or Combined Injections of Antiserum against Partially Purified Chicken Luteinizing Hormone (CM2), Indomethacin and Arginine Vasotocin on Oviposition in Laying Hens

Effects of Single or Combined Injections of Antiserum against Partially Purified Chicken Luteinizing Hormone (CM2), Indomethacin and Arginine Vasotocin on Oviposition in Laying Hens

Effects of mammalian and avian gonadotropins on in vitro progesterone production by avian ovarian granulosa cells

Chicken ovarian granulosa cells were incubated in vitro following their preparation by collagenase treatment. The secretion of progesterone by the cell suspension was increased (between 2.3- and 3.8-fold) by the addition of either avian or mammalian luteinizing hormone (LH). The effectiveness of chicken gonadotropin fractions in stimulating progesterone release agrees well with their known LH contents. The addition of an antiserum against avian LH, to the incubation, blocked the effect of chicken LH on progesterone release. Mammalian FSH induced small (20 to 70%) increases in progesterone secretion.

Isolation and characterization of luteinizing hormone and follicle-stimulating hormone from pituitary glands of the turkey ( Meleagris gallopavo)

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were purified from the pituitary glands of the turkey ( Meleagris gallopavo). These hormones were characterized biochemically and biologically and compared with chicken gonadotropins prepared in several independent laboratories. Amino acid and carbohydrate analyses demonstrated homology between turkey and other species of gonadotropin. The turkey LH purified here had significantly higher carbohydrate content than a previous preparation of turkey LH. Immunological studies further confirmed that the turkey FSH and LH were distinct from one another and that each was homologous to the respective gonadotropin from other vertebrates; the immunopotencies of the turkey hormones were similar to those from chickens. A variety of bioassays and radioreceptor assays (RRAs) confirmed the biological activity of the two turkey gonadotropins and revealed that the turkey LH was distinct from that of the chicken. As expected, the two types of turkey hormones were approximately equipotent in total gonadotropin bioassays (frog spermiation and 32P uptake by chick testes), and only the turkey LH was active in the rat Leydig cell assay and in RRA for LH in mammals. However, the turkey LH was also highly potent in several assays considered to be relatively FSH specific, including the Anolis lizard assay and several RRA systems using mammalian, turtle and avian gonadal receptors with 125I-labeled human FSH as tracer. Turkey and chicken FSH are similar in the RRAs, but the turkey LH was consistently more potent than either avian FSH in competing for FSH-binding sites. Chicken LH had relatively low activity by comparison. It is suggested that the evolution of the structure of active sites in turkey LH has involved convergence on those of the FSH molecule.

The endocrine control by luteinizing hormone of testosterone secretion from the testis of the Japanese quail

Injections of chicken or ovine luteinizing hormone (LH) into sexually mature male Japanese quail greatly increased plasma levels of testosterone. Maximal responses were obtained within 15 min of an iv injection and between 1 and 2 hr following sc or im injections. Saline treatment had no effect on plasma testosterone. In chronically castrated quail LH was not effective in altering androgen levels. The responses to LH were dose related, significant increases being obtained following sc injections of 5 μg of chicken LH (fraction AE1) or 10 μg of ovine LH (NIH-LH-S19). Chicken LH (AE1) was appropriately 1.8 times as potent as NIH-LH-S19. Ovine FSH (NIH-FSH-S10) stimulated testosterone release in very large doses (1 mg) but was at least 100 times less active than LH-S19. An iv injection of an antiserum raised against chicken LH into mature male quail caused a rapid decrease in plasma testosterone levels. Treatment with FSH-S-10 for up to 1 week failed to facilitate the subsequent response to an injection of LH. The responsiveness of the testis to exogenous LH was tested at various times during a photoinduced gonadal growth cycle. Sexually immature quail showed only a marginal response to an sc injection of 20 μg of NIH-LH-S19. A marked increase in responsiveness occurred after 6 long days. This coincides with the time when plasma testosterone levels increase naturally after transfer to long daylengths and with the period when Leydig cell maturation becomes complete. These in vivo results add further weight to the belief that, in birds, or at least in the quail, peripheral androgens are controlled by pituitary LH and that FSH plays no significant role in the acute release of testosterone from the mature testis.

In vivo effects of an antiserum to partially purified chicken luteinizing hormone (CM2) in laying hens

An injection of an antiserum raised against partially purified chicken LH (fraction CM2) in laying hens resulted in a cessation of laying for about 5 days and caused extensive atresia of the ovary. Ovulation was blocked before there were macroscopic signs of follicular atresia. Since the antiserum contained antibodies against TSH and possibly FSH, these effects may not have been entirely due to the inhibition of LH activity.

Effects of chicken and ovine luteinizing hormone on androgen release and cyclic AMP production by isolated cells from the quail testis

Cellular suspensions were prepared from mature quail testes using collagenase. Approximately 30% of the cells could be identified as Leydig cells. The addition of chicken or ovine luteinizing hormone (LH) greatly increased androgen (testosterone plus any dihydrotestosterone_ release and log-linear responses were obtained. The minimally effective doses of chicken LH (AE 1) and ovine LH (NIH LH-S18) were about 2 and 4 ng, respectively. An antiserum to chicken LH blocked the effects of chicken but not of ovine LH. LH had no effect on the low levels of testosterone released by isolated seminiferous tubules. The action of LH was potentiated 1.5- to 3-fold in the presence of phosphodiesterase inhibitors such as 1-methyl-3-isobutyl xanthine or theophylline. Cyclic AMP stimulated testosterone release and a dose-response curve was established for dosages between 2.5 and 60 m M per tube. Chicken LH increased cyclic AMP formation in the isolated interstitial cells within 5 min of adding a large dose; the first signs of enhanced testosterone release were not detectable until 30 min had elapsed. A dose-response relationship existed between chicken LH and cyclic AMP formation although the minimally effective dose was 125 ng. Cycloheximide inhibited LH-induced testosterone release but not the rise in intracellular cyclic AMP formation. Actinomycin D reduced both the testosterone and cyclic AMP responses to LH.

The half-life of luteinizing hormone in the circulation of domestic fowl and Japanese quail.

The rate of disappearance of luteinizing hormone (LH) from the circulation is an important parameter in studying the dynamics of the hormone and in interpreting the significance of both circulating and pituitary hormonal levels. This rate is most frequently expressed in terms of the half-life of LH in the circulation (see Parlow, 1968). The estimation of the half-life of circulating LH in birds has been made feasible by the availability of purified chicken gonadotrophins (Stockell Hartree & Cunningham, 1969; Scanes & Follett, 1972), together with a radioimmunoassay for avian LH (Follett, Scanes & Cunningham, 1972). The half-life of LH in the domestic fowl was determined by following the dis-appearance of either unlabelled LH or 125I-labelled LH from the circulation of the bird. In the case of the labelled hormone, a chicken LH fraction of high ovarian ascorbic acid depleting activity and low thyrotrophin content (fraction AEI, Scanes & Follett,

Cross-reaction in a chicken LH radioimmunoassay with plasma and pituitary extracts from various species

A radioimmunoassay for chicken luteinizing hormone (LH) was used to investigate possible cross-reactions with plasmas and pituitary extracts from a range of vertebrates. Dose-response curves parallel with that for chicken LH were found with the ten bird species tested and with pituitary extracts from three reptiles. Mammalian gonadotrophins showed little or no cross-reaction in the assay. Results with lower vertebrate material were more varied. The results are discussed in terms of the usefulness of the assay in avian reproductive endocrinology.

A RADIOIMMUNOASSAY FOR AVIAN LUTEINIZING HORMONE

SUMMARY A radioimmunoassay for avian luteinizing hormone (LH) is described, using antisera raised against chicken pituitary gonadotrophins of varying degrees of purity, and purified chicken LH for radio-iodination. A postprecipitation double antibody method was developed with a sensitivity to 30–60 pg of purified chicken LH. The specificity of the method was investigated. Fractions of follicle-stimulating hormone with high biological activity showed little immunological activity, whilst all the fractions of LH tested showed strong immunological potency. Human, ovine and bovine LH showed virtually no cross-reaction. The method measures immunoreactive LH in 25–200 μl plasma from chickens and quail. The plasma levels correlate well with known physiological processes, being absent in hypophysectomized birds and low in sexually immature quail. When testicular growth begins in quail the level rises eightfold; castration increases it still further while the level is lowered by testosterone. Manipulation of the pituitary-thyroid system in quail did not significantly affect the level of plasma activity. Estimates of activity are independent of either the antiserum or the iodinated preparation of LH used in the assay. The antisera used all blocked gonadotrophic activity in vivo.

The influence of chicken luteinizing hormone on radioactive phosphorus uptake and incorporation into pullet ovarian RNA, DNA, protein, phospholipid and acid-soluble fractions (chicken LH effects on the ovary)

1. 1. A comparative response in stimulation of 32P uptake was made in 1- to 3-day-old pullets; 2.5 μg of chicken luteinizing hormone (LH) produced a 187 per cent increase in uptake over the controls, while an equivalent amount of bovine LH had no effect on 32P uptake. 2. 2. The stimulative effect of chicken LH on ovarian 32P uptake reached a maximum 30 min following the injection of the hormone. 3. 3. Increased 32P activity was noted in all chemical fractions 30 min following LH treatment. However, a significant increase in activity of the RNA fraction was detected within 15 min after treatment.

Purification of chicken pituitary follicle-stimulating hormone and luteinizing hormone.

SUMMARY Separation and partial purification of chicken pituitary follicle-stimulating hormone (FSH) and luteinizing hormone (LH) has been obtained by methods which were effective in the purification of the corresponding human and horse hormones. Increases in chicken LH activity were observed after chromatography on DEAE-cellulose and on Amberlite IRC-50 suggesting removal of an LH inhibitor. The biological potencies of chicken FSH and LH preparations when assayed in mammals were very much lower than those of the corresponding mammalian fractions on a weight basis. A weak immunological cross-reaction between chicken and human pituitary LH was used to estimate LH in chicken pituitary fractions and the results were compared with bioassays of the same fractions.