ABSENCE OF AN IMMUNOLOGICALLY DISTINCT FOLLICLE-STIMULATING HORMONE RELEASING FACTOR IN RAT STALK MEDIAN EMINENCE EXTRACTS

1976 ◽  
Vol 68 (1) ◽  
pp. 89-94 ◽  
Author(s):  
M. SHAHMANESH ◽  
S. L. JEFFCOATE
Keyword(s):  
Median Eminence ◽  
Male Rats ◽  
Rabbit Serum ◽  
Normal Rabbit Serum ◽  
Pituitary Tissue ◽  
Rat Pituitary ◽  
Pre Treatment ◽  
Lh Rh ◽  
Dose Levels

SUMMARY Rat stalk median eminence (SME) extract was incubated with various quantities of an antiserum raised against synthetic luteinizing hormone releasing hormone (LH-RH) and the resulting material was used at two or more dose levels to stimulate release of LH and FSH from anterior pituitary tissue, obtained from male rats, incubated in vitro. The resulting dose–response lines were used to obtain the LH- and FSH-releasing potency of the material, expressed as a percentage of SME extract pre-incubated with normal rabbit serum. Treatment with various doses of antiserum reduced LH-releasing and FSH-releasing potencies to a similar extent. Stalk median eminence extract and synthetic LH-RH were incubated with antiserum and directly compared in the same experiment in vitro. The changes in LH and FSH release caused by pre-treatment with antibody were similar for SME extract and synthetic LH-RH. In a final experiment, SME extract was passed through a column of Sepharose 2B particles to which was coupled anti-LH-RH antibody. The resulting material, when mixed with synthetic LH-RH and used to stimulate rat pituitary tissue in vitro caused a similar increase in the LH- and FSH-releasing potencies of the synthetic decapeptide. It is concluded that rat SME extract contains a single releasing factor for LH and FSH immunologically indistinguishable from synthetic LH-RH.

Effect of pre-treatment of long-term ovariectomized rats with anti-LRH on the response of the pituitary gland in vitro to the analogue of LRH D-ser-(tBu)6-des-gly10-ethylamide-LRH (Buserelin®)

1983 ◽  
Vol 104 (3) ◽  
pp. 272-278 ◽  
Author(s):  
G. P. van Rees ◽  
J. A. M. J. van Dieten ◽  
J. de Koning ◽  
A. F. P. M. de Goey
Keyword(s):  
Pituitary Gland ◽  
Ovariectomized Rats ◽  
Rabbit Serum ◽  
Normal Rabbit Serum ◽  
Basal Release ◽  
Pituitary Glands ◽  
Lh Release ◽  
Pre Treatment

Abstract. Ovariectomized rats were injected iv with an antiserum against LRH or normal rabbit serum. AntiLRH caused a decrease of plasma LH and FSH. After 24 or 48 h, the rats were decapitated and the pituitary glands incubated in the presence of an analogue of LRH which reacts minimally with anti-LRH (Buserelin). Pretreatment with anti-LRH caused an increased response of pituitary LH release to Buserelin. Similar results were obtained with regard to FSH. In this case, however, basal release of FSH was lowered by pre-treatment with antiLRH. Pituitary LH and FSH contents were not affected by anti-LRH, but synthesis of LH and FSH in vitro was smaller than in control glands obtained from rats pretreated with normal rabbit serum.

NEGATIVE FEEDBACK OF SECRETION OF FOLLICLE-STIMULATING HORMONE BY THE PITUITARY GLAND OF DEVELOPING MALE RATS

1980 ◽  
Vol 87 (3) ◽  
pp. 401-407 ◽  
Author(s):  
A. R. SHETH ◽  
GEETA R. VANAGE ◽  
A. Y. VAZE ◽  
A. N. THAKUR
Keyword(s):  
Binding Capacity ◽  
Rabbit Antiserum ◽  
Male Rats ◽  
Rabbit Serum ◽  
Normal Rabbit Serum ◽  
Human Seminal Plasma ◽  
In Vitro Binding ◽  
Vitro Binding ◽  
Age Dependent

Rabbit antiserum to human seminal plasma inhibin (hSPI) was administered subcutaneously to developing male rats of 5, 10, 14, 17 and 24 days of age and the size of the endogenous FSH rise in serum was measured. The FSH levels were threefold higher on day 9 and 1·5-fold higher on days 14 and 18 when compared with levels in control rats treated with normal rabbit serum. Furthermore, the in-vitro binding capacity of pituitary plasma membrane to 125I-labelled hSPI declined with increase in age of the rats. Thus, the results of the present study suggest that the sensitivity of the testicular inhibin–FSH feedback relationship is related to age-dependent changes in pituitary binding of inhibin.

NEUTRALIZATION OF ACTIVITY OF CIRCULATING GONADOTROPHIC HORMONES BY ANTISERUM TO RAT PITUITARY

1963 ◽  
Vol 25 (4) ◽  
pp. 451-456 ◽  
Author(s):  
A. N. CONTOPOULOS ◽  
T. HAYASHIDA
Keyword(s):  
Serum Proteins ◽  
Follicular Development ◽  
Inhibitory Effect ◽  
Female Rats ◽  
Male Rats ◽  
Rabbit Serum ◽  
Normal Rabbit Serum ◽  
Hormone Activity ◽  
Immature Female ◽  
Rat Pituitary

SUMMARY Antiserum prepared by the immunization of rabbits, with homogenates of rat anterior pituitary gland according to a procedure previously outlined, was absorbed with homologous serum proteins and tissues to remove various non-specific antibodies. Varying levels of plasma from gonadectomized male rats, containing high levels of gonadotrophic hormone activity, were injected into hypophysectomized, immature female rats. The simultaneous injection of antiserum resulted in complete neutralization of gonadotrophic hormone as judged by the inhibition of ovarian and uterine weight responses and the extent of follicular development in the ovaries of the rats used for the bioassay. The degree of inhibition was dependent upon the relative amount of antiserum employed. Normal rabbit serum did not have any inhibitory effect. No detectable non-specific or toxic effects were noted in the animals injected with antiserum.

IMMATURE RAT PITUITARY GLANDS IN VITRO: AGE- AND SEX-RELATED CHANGES IN LUTEINIZING HORMONE RELEASING HORMONE-STIMULATED GONADOTROPHIN RELEASE

1977 ◽  
Vol 73 (2) ◽  
pp. 309-319 ◽  
Author(s):  
J. DULLAART
Keyword(s):  
Male Rats ◽  
Steady Increase ◽  
Releasing Hormone ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Lh Release ◽  
The One ◽  
Lh Rh ◽  
Lh Releasing Hormone

SUMMARY Pituitary glands from immature female and male rats aged between 5 and 30 days were incubated in vitro and the effect of LH releasing hormone (RH) on the release of LH and FSH was studied. Pituitary gonadotrophin contents were also measured. Gonadotrophin release showed changes with age as well as sex differences: after LH-RH stimulation the female pattern of release of LH and FSH (expressed per mg pituitary tissue) showed a peak at day 15; the male pattern of LH release was characterized by a steady increase with age, whereas FSH release stayed more or less constant from day 10 onwards. In both sexes the LH:FSH ratio increased with age, both in pituitary gonadotrophin content and in the mixture of gonadotrophins released. It is discussed, that the prepubertal development of pituitary gonadotrophic function might be determined on the one hand by rather autonomous growth processes (more or less similar in female and male hypophyses) and on the other hand by modulating influences of sex steroid hormones, which are different in female and male animals.

Release of bioactive ACTH by perifused human placenta at early and late gestation

1993 ◽  
Vol 136 (2) ◽  
pp. 345-353 ◽  
Author(s):  
B. J. Waddell ◽  
P. J. Burton
Keyword(s):  
Human Placenta ◽  
Late Gestation ◽  
Rabbit Serum ◽  
Maximal Response ◽  
Normal Rabbit Serum ◽  
Apparent Difference ◽  
Adrenocortical Cells ◽  
Adult Rats ◽  
Constant Rate

ABSTRACT This study assessed whether bioactive ACTH is released by the human placenta during perifusion in vitro at early and late gestation. Human placental villous fragments from early (8–12 weeks) and late (38–40 weeks) gestation were perifused at a constant rate for 6·5 h. To assess ACTH-like bioactivity released by this tissue, the perifusion effluent was redirected through adjacent chambers containing freshly dispersed adrenocortical cells obtained from adult rats. Baseline secretion of corticosterone by these adrenocortical cells averaged 95±26 (s.e.m.) fmol/min, and this increased at least fivefold (P <0·01, two-way ANOVA) in response to placental effluent at early and late gestation. The magnitude of this increase, expressed as a percentage of the maximal response to a subsequent stimulus with ACTH(1–24), was similar for placentas obtained at early (41 ± 12% of maximal response) and late (42 ± 17%) gestation. Immunoreactive (I)-ACTH was readily detectable in placental effluent from all preparations (5·5±2·3 fmol/min per g tissue), and there was no apparent difference with stage of gestation. To determine whether all of the ACTH-like bioactivity released by the placenta was attributable to I-ACTH, a second series of placental/adrenal perifusions was conducted. In these, I-ACTH was selectively removed from placental effluent by immunoneutralization, and the residual bioactivity measured. Immunoneutralization involved preincubation of placental effluent with ACTH antiserum (1:100), and preincubation with normal rabbit serum (NRS) served as a control. Preincubation with ACTH antiserum, but not with NRS, resulted in a marked reduction in ACTH-like bioactivity present in placental effluent at both early (P <0·01, paired t-test) and late (P <0·05) gestation. This inhibition was significantly more effective (P <0·05, unpaired t-test) at early than at late gestation. Overall, these data establish that the human placenta can release bioactive ACTH-like activity at both early and late gestation, and that much, but not all, of this bioactivity is directly attributable to I-ACTH. These findings clearly demonstrate a potential role for placental ACTH in directly influencing the maternal and/or fetal hypothalamic-pituitary-adrenal axes during human pregnancy. Journal of Endocrinology (1993) 136, 345–353

Partial purification of antigens collected during in vitro cultivation of the larval stages of Taenia pisiformis

Parasitology ◽  
1976 ◽  
Vol 72 (3) ◽  
pp. 269-279 ◽  
Author(s):  
M. D. Rickard ◽  
J. C. Katiyar
Keyword(s):  
Protective Immunity ◽  
Culture Medium ◽  
Serum Proteins ◽  
Skin Tests ◽  
Rabbit Serum ◽  
Partial Purification ◽  
In Vitro Cultivation ◽  
Normal Rabbit Serum ◽  
Skin Reactions

SummaryLarvae of Taenia pisiformis were cultured in vitro in medium containing 2·5, 5 or 20% (v/v) of normal rabbit serum (NRS). Greatest development occurred in 20% NRS, and the potency of antigens collected in medium from each culture tested by intradermal (i/d) skin tests in infected rabbits paralleled the in vitro growth rate of larvae. ‘Culture’ antigens from 5% NRS stimulated good immunity in rabbits to a challenge infection with T. pisiformis eggs, although they were poorly reactive in skin tests.T. pisiformis larvae were also cultured in 10% (v/v) of nitrates of serum reduced to one-half of its volume by passage through 300 000 MW cut oif (XM300F) or 100000 MW cut off (XM100F) ultrafiltration membranes. Larvae cultured using XM300F had growth rates comparable with those cultured in 20% NRS, and the antigens released into the culture medium had equal potency in i/d tests and in stimulating protective immunity in rabbits. Larvae did not develop in XM100F orproduce skin-reactive or protective antigens.Crude ‘culture’ antigen from cultures in 20% NRS was separated into 4 fractions by nitration on Sephadex G200. All of these fractions gave i/d skin reactions in infected rabbits. Fraction 3 (F3) was the most active, but was shown by acrylamide gel electrophoresis and immunoelectrophoresis to be highly contaminated with rabbit serum proteins. F3 was separated into fractions on DEAE-Sephadex A50, and the third fraction from this was as active as the original culture medium in i/d skin tests, but had only 5% of the original protein concentration. Electrophoresis demonstrated few serum contaminants, and 2 indistinct protein bands that were not present in a similar fraction of NRS.Neither Sephadex G200 F3 nor DEAE-Sephadex F3 stimulated protective immunity in rabbits, suggesting that antigens stimulating immunity against the establishment of T. pisiformis in rabbits and those provoking cell-mediated immune reactions may be different.

BIOSYNTHESIS OF GONADOTROPHINS BY RAT PITUITARIES IN VITRO

1975 ◽  
Vol 66 (3) ◽  
pp. 369-374 ◽  
Author(s):  
MRIDULA CHOWDHURY ◽  
EMIL STEINBERGER
Keyword(s):  
Comparative Study ◽  
Anterior Pituitary ◽  
Male Rats ◽  
Leucine Incorporation ◽  
Experimental Conditions ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Endogenous Proteases ◽  
Pituitary Homogenate

SUMMARY A method has been developed for studying biosynthesis of FSH in the rat pituitary in vitro. Anterior pituitary glands were incubated with [3H]leucine; a specific and sensitive immunoprecipitation technique was used to isolate FSH from the pituitary homogenate. Total FSH content of the samples was measured by a double-antibody radioimmunoassay technique. Using this technique, a comparative study of LH and FSH synthesis in the same pituitary of adult male rats incubated for various intervals (0·5–6 h) was done. Increased incorporation of [3H]leucine into both LH and FSH with time was noted. The rate and amount of [3H]leucine incorporation into FSH was found to be higher than that into LH, indicating that either the rate of FSH synthesis is higher than that of LH or FSH has more leucine residues than LH. Greater susceptibility of LH to degradation by endogenous proteases during dialysis may also reflect less incorporation of [3H]leucine into LH. This method provides a reliable tool for evaluating FSH synthesis under various experimental conditions.

EFFECT OF ACTINOMYCIN D ON THE PITUITARY RESPONSE TO LH-RH

1976 ◽  
Vol 81 (1) ◽  
pp. 73-81 ◽  
Author(s):  
Jesus A. Vilchez-Martinez ◽  
Akira Arimura ◽  
Andrew V. Schally
Keyword(s):  
Initial Phase ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Male Rats ◽  
Continuous Stimulation ◽  
Immature Male ◽  
Serum Lh ◽  
Pre Treatment ◽  
Lh Rh

ABSTRACT The effect of Actinomycin D (Act D) on the release of LH and FSH induced by LH-RH was investigated in rats. Immature male rats received an iv infusion over a period of 3–4 h or a quick iv injection of synthetic LH-RH. Infusion of LH-RH significantly increased serum LH and FSH levels at 1, 2, 3 and 4 h after the initiation of infusion. Pre-treatment with 100 μg/100 g b. w. Act D failed to affect the rise of serum LH and FSH levels 1 h after the infusion but significantly suppressed the response at 2, 3 and 4 h. The increase in serum LH and FSH levels after a quick injection of LH-RH was unaffected by pre-treatment with Act D whether the antibiotic was injected 1 or 2 h before LH-RH. The results suggest that the initial phase of the pituitary response to LH-RH does not require DNA-dependent RNA synthesis, whereas that in the later period does. RNA synthesis may be necessary only to maintain the increased secretion of both LH and FSH during a continuous stimulation with LH-RH.

INFLUENCE OF STEROID SEX HORMONES ON THE F. S. H.-RELEASE BY RAT HYPOPHYSES IN VITRO

1961 ◽  
Vol 36 (4) ◽  
pp. 485-497 ◽  
Author(s):  
G. P. van Rees
Keyword(s):  
Sex Hormones ◽  
Female Rats ◽  
Male Rats ◽  
Intact Female ◽  
Intact Male ◽  
Incubation Experiments ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Steroid Sex Hormones

ABSTRACT The hypothesis that steroid sex hormones influence pituitary F. S. H. by independent actions on its production and capacity of the gland to release it has been investigated by means of incubation experiments. During incubation, rat pituitary glands released considerable amounts of F. S. H. into the medium. Inactivation of F. S. H. during incubation could not be demonstrated; once (in females) some production of F. S. H. was even observed. The amount of F. S. H. which is released into the medium is influenced by the quantity of F. S. H. stored in the hypophyses. Hypophyses from male rats pretreated with oestradiol released relatively more F. S. H. into the medium than hypophyses from control animals. On the other hand, pretreatment with testosterone caused the pituitary glands to release less F. S. H. into the medium. In agreement with these results, hypophyses from intact male rats released relatively less F. S. H. than hypophyses from intact female rats. These facts support the hypothesis that androgens depress pituitary F. S. H.-secretion by inhibiting the capacity to release it, while oestrogens, which can even promote this property of the pituitary gland, also act by directly inhibiting its production.

scholarly journals IMMUNE RESPONSE OF RABBITS TO INJECTION OF PLASMODIUM KNOWLESI

1939 ◽  
Vol 70 (2) ◽  
pp. 131-139 ◽  
Author(s):  
Monroe D. Eaton ◽  
L. T. Coggeshall
Keyword(s):  
Immune Response ◽  
Plasmodium Knowlesi ◽  
Conclusive Evidence ◽  
Red Cells ◽  
Rabbit Serum ◽  
Normal Rabbit Serum ◽  
Passive Protection ◽  
Normal Monkey ◽  
Protective Antibodies

Specific complement-fixing antibodies are produced in the serum of rabbits in response to injections of living or dead Plasmodium knowlesi. Sera from rabbits receiving injections of either parasitized or normal monkey erythrocytes are parasiticidal in vitro for P. knowlesi. Because absorption of parasiticidal rabbit sera with normal monkey erythrocytes abolishes the parasiticidal effect, it is concluded that the effect is largely due to an antibody to the red cells. Normal rabbit serum is not parasiticidal. Experiments on passive protection in monkey malaria with serum from rabbits which have received intraperitoneal injections of living or dead P. knowlesi yield no conclusive evidence that protective antibodies are formed.

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