Crude Pituitary Extract Research Articles

Sperm characteristics and growth of Rhamdia quelen males fed on rations formulated with vegetable food and different digestible energy levels supplied by soy bean oil / Short Communication Características espermáticas e crescimento de machos Rhamdia quelen alimentados com rações formuladas com alimentos vegetais e diferentes níveis de energia digestível fornecidos pelo óleo de soja

This research was carried out to evaluate the effects of rations formulated with vegetable foods and different levels of digestible energy supplied by soybean oil, on sperm characteristics and growth of Rhamdia quelen males. The fishes were fed on over 255 days with rations containing 350 g crude protein (CP) kg -1 and 2700, 2950, 3200, 3450 and 3700 kcal of digestible energy (DE) kg -1 . A randomized experimental design was used with five treatments and three replicates. A 8 m 2 tank containing six females and three males was an experimental unit. The fishes were weighted fortnightly to correct the feeding rate. All males receipted an intramuscular injection of 2.5 mg of crude pituitary extract (CPE) kg -1 to perform the sperm collection. The sperm characteristics were assessed on fresh sperm immediately after collection. All data were subjected to ANOVA and regression analysis. The growth, sperm volume, sperm concentration, or time of sperm motility were not affected (p < 0.05) by rations. In addition, ration containing 3318.75 kcal of DE kg -1 improved the integrity of sperm membrane, suggesting a theoretical higher sperm survival rate of 98.22%. In conclusion, ration formulated with vegetable foods and different levels of soy bean oil as energy source did not interfere on growth of Rhamdia quelen males. In addition, the diet energy supplied by mainly soy bean oil offered a nutritional condition that improved the sperm quality since males fed on ration with 3318.75 kcal of digestible energy kg -1 has been increased the membrane integrity of sperm cell.

Induced reproduction and early development in dourado, Salminus franciscanus Lima & Britski, 2007 (Pisces: Characiformes).

Our study aimed to establish the response of Salminus franciscanus to hypophysation and describe the main morphological events of its embryonic process. Wild fish were captured in São Francisco River and selected broodstock (females: 66.4 ± 11.1 cm and 4.04 ± 2.32 kg; males: 58.3 ± 10.2 cm and 3.62 ± 1.12 kg) were kept at 26.1 ± 0.6°C for induction of final maturation/gamete release via the hypophysation technique. In females, two doses (0.8 and 5.6 mg/kg body weight) of crude pituitary extract of common carp (Cyprinus carpio) were administered with a 14 h interval. For males, a single dose (2.7 mg/kg body weight) of crude pituitary extract was applied at the same time as the females' second dose. Oocytes and sperm were manually stripped 8 h after a females' second hormonal dose. Fertilization was carried out using the dry method. Eggs were kept in funnel-type 60 L incubators at 24.3 ± 0.3°C and were analyzed and photographed every 10 min. After hormonal induction, 60% of females and 100% of males reacted positively and no broodstock mortality was recorded. The females released an average of 385.2 ± 78.4 g of oocytes and the fertilization rate observed was 50.4 ± 12.3%. The blastopore closure occurred at 7.5 h, somite formation at 12 h and hatching at 20 h post-fertilization. In general, the results of this study improve the understanding of the reproductive biology of dourado and confirm its potential for fish farming in the neotropical region.

Feed Additives in Enhancing Milk Production. A Review

Soil acidity Feed components are merchandise utilized in animal nutrients to enhance the nice of feed and the pleasant of meals from animal origin, or to improve the animals’ overall performance and In Ethiopia, dairy manufacturing relies upon especially on indigenous livestock genetic sources; extra particularly on cattle, goats, camels, and sheep. Therefore, the results of somatotropin at the performance of lactating animals were the problem of a hobby for over 50 years. It becomes, to begin with, confirmed that injections of crude pituitary extract improved milk production in dairy cows. On the opposite hand, four factors may be considered to decide if a feed additive needs to be used: Anticipated reaction, financial go back, available research, and Field responses. But manufacturers are endorsed to significantly evaluate the fee-to-benefit ratio of each feed additive in their management structures. In normally feed additives fall into much different paperwork and can be useful in decreasing consequences of ruminal acidosis, enhancing feed efficiency, a charge of advantage, heat suppression and bloat manage to call a completely few. When nicely utilized in properly-managed surroundings, a lot of these components can improve performance and profitability extensively. This assessment discussed several feed additives used for boosting milk production.

Homoplastic hypophysation of African catfish, Clarias gariepinus

Clarias gariepinus brood stocks (137.0 6.0g) were hypophysised for maturation and ovulation with Clarias crude pituitary extract (CCPE) at 7 mg/kg body weight of female fish. Fertilization was done by mixing egg and mill together in a dry bowl with feather. Physico-chemical parameters of water were maintained at 6.0 +0.2 mg/l (dissolved oxygen), 28.0 +0.5°C (temperature) and 7.2, 0.1 (pH). The latency period recorded for optimal egg was 10-12 hours. While hatching started at 24 hours to 36 hours. The total number of eggs stripped was 618.8 10, the total fertilized was 332.8 x 10', the total fry hatched was 280.6 x 10%. It is concluded that C. gariepinus can be induced with CCPE to reduce the cost of carp pituitary and problem of its procurement due to scarcity.

Initial development of Prochilodus hartii (Pisces: Prochilodontidae) submitted to induced reproduction.

The Prochilodontidae prepare for reproduction in captivity, but neither ovulation nor spawning occurs, thus requiring induced reproduction for breeding and restocking. This study analyzed for the first time the embryogenesis and larval ontogeny of P. hartii submitted to induced reproduction by hypophysation with crude common carp pituitary extract. The extrusion of oocytes and sperm was performed manually and fertilization was done using the dry method. After fertilization, the eggs were kept in incubators at 23°C. A stereomicroscope was used to measure egg diameter and to monitor embryo development. Samples of larvae were collected daily for 7 days for histological and biometric analyses. The recently extruded oocytes, non-hydrated, are spherical, grey, and non-adhesive with a diameter of 1480 ± 39 μm and after hydration, have a diameter of 2860 ± 120 μm. The positive response to hypophysation was 100% for females and 80% for males. Spawning occurred 7 h after the third hormonal dosage. The fertilization rate was 77% at 23°C. Blastopore closure occurred at 6 h 45 min and embryonic development was completed 36 h 10 min after fertilization. After 204 h post fertilization (hpf) the larvae reached a standard length of 6.56 ± 0.14 mm with the yolk sac completely resorbed. In P. hartii, the oral cavity opening occurred 132 hpf. The results of this study provide knowledge to better understand induced reproduction, breeding, and management of P. hartii, a species with a high potential for pisciculture, and which is commercially important in the Jequitinhonha River basin.

Desova induzida de curimatã-pacu submetido a dois protocolos de hipofisação

O objetivo deste trabalho foi comparar dois protocolos de hipofisação, na indução à desova de curimatã-pacu.Testou-se a aplicação de dose única ou duas doses de extrato bruto de hipófise de carpa-comum. Não houve diferença significativa entre os protocolos quanto às taxas de fêmeas que desovaram, fertilização e larvas deformadas. A aplicação de dose única resultou em valores de horas-graus até a extrusão dos ovócitos maiores do que em duas doses. A aplicação de uma única dose representou menor consumode água, energia e tempo. O protocolo da dose única pode ser utilizado como alternativa para a indução à desova de curimatã-pacu.

Genetic effect of growth hormone gene on yearling weight and wool traits in Zel sheep (Brief Report)

Abstract. The growth hormoe (GH) gene is a candidate for growth in sheep, since plays an important role in growth regulation and development (Boyd & Bauman 1989). Most genetic studies on the growth of sheep have concentrated on birth weight, weaning weight and yearling weight (Bathaei & Leroy 1998). Pereira et al. (2005) found significant effect for bovine growth hormone (bGH) genotype on yearling weight. Tambasco et al. (2003) observed a positive association between genotype LV and daily body weight gain from weaning to yearling in Bos Taurs x Bos indicus crosses. Wool traits like greasy fleece weight, clean yield, fiber diameter and its coefficient of variation are very important selection goals in sheep breeding programs, however new traits such as staple strength and staple length are of increasing importance in the wool industry (Forgarty 2006). Initial observations using daily injections of crude pituitary extracts showed that wool growth decreased by 17 % during the second treatment period (Ferguson 1954). Allain et al. (1998) found segregation for coefficient of variation of fiber diameter and staple length on chromosomes 3 and 4 in a composite sheepline (INRA401). Zel sheep is raised in North of Iran. This sheep is a native non-fat tailed breed with small-sized (Saadat-Noori & Siah-Mansoor 1990). The aim of this study was to investigate the relationship between GH genotypes and wool traits and yearling weight using single strand conformation polymorphism (SSCP) method in Zel sheep.

Biology of eggs, embryos and larvae ofRhinelepis aspera(Spix & Agassiz, 1829) (Pisces: Siluriformes)

The black armoured catfish Rhinelepis aspera is an important commercial species found in the São Francisco River (Brazil) that has great potential for pisciculture. This paper presents, for the first time, information on the embryogenesis and larval development of this species. The breeder fish were subjected to spawning induction with crude carp pituitary extract. Eggs were kept in incubators at 24 degrees C and embryogenesis was observed with a stereomicroscope until hatching. Ovary fragments, samples of recently extruded oocytes and larvae were fixed in Bouin's solution and subjected to routine histology techniques. Recently extruded oocytes were also analyzed with a scanning electron microscope (SEM). Females (80%) had a positive response to hypophysation. Oocyte extrusion was performed at 8 h and 30 min after the second hormone injection and the fertilization rate achieved 72.4 +/- 8.8%. Recently extruded oocytes had a mean diameter of 1360.80 +/- 40.87 microm and presented a conspicuous jelly coat covering the zona pellucida. Histochemical reactions indicated the presence of neutral glycoproteins in the yolk globules and in the zona pellucida. These reactions also indicated the presence of neutral glycoproteins and carboxylated acid glycoconjugates in the follicular cells and the jelly coat. These compounds form mucosubstances that can be related to the adhesiveness of the eggs. Under the SEM the oocytes presented a micropyle disc and a thick jelly coat over their surface. The closure of the blastopore occurred 9 h and 40 min after fertilization and embryogenesis was completed at 45 h and 50 min after fertilization, when the embryos were incubated at 24 degrees C. The total absorption of the yolk sac occurred during the fifth day indicating the need for an exogenous food supply. These results provide essential information for the successful breeding and management of the promising R. aspera.

Utilização do espermatócrito para estimar a concentração espermática no sêmen da piabanha (Brycon insignis)

O objetivo deste trabalho foi verificar a viabilidade da utilização do espermatócrito para estimar a concentração espermática do sêmen de piabanha. Os exemplares (n=29) de piabanha Brycon insignis foram hipofisados, sendo posteriormente realizada a coleta de sêmen. O espermatócrito foi determinado utilizando-se micro-centrífuga de tubos capilares. A concentração espermática foi verificada por contagem em câmara de Neubauer, após diluição. A concentração espermática verificada (média±desvio padrão) foi de 24,38 ± 3,84 x 10(9) espermatozóides / mL, e o espermatócrito foi de 16,14±5,20%. A equação de regressão: v = 14,01.10(9) + 0,6428.10(9).X foi significativa (P<0,01) e apresentou R² ajustado = 0,75. Deste modo, é possível estimar a concentração através da determinação do espermatócrito.

Reprodução induzida da piabanha, Brycon insignis (Steindachner, 1876), mantida em cativeiro

Estudos de reprodução induzida da piabanha, Brycon insignis, foram realizados em janeiro-fevereiro/96 e fevereiro/97, utilizando-se exemplares de 3 a 5 anos de idade, mantidos em cativeiro na Estação Experimental da Seção de Hidrobiologia e Aqüicultura, pertencente à CESP (Companhia Energética de São Paulo), localizada na cidade de Paraibuna, SP. As fêmeas selecionadas para indução da reprodução apresentaram ventre abaulado, papila genital saliente e avermelhada e 60% dos ovócitos com núcleo em posição excêntrica. Trinta e três fêmeas foram induzidas à reprodução com dose única de hCG de 5 UI/g (gonadotropina coriônica humana); 17 receberam duas aplicações de extrato bruto de hipófise de carpa, de 0,5 e 5,0 mg/kg, com intervalo de 10 horas entre as aplicações; 18 receberam 0,5 mg/kg de extrato bruto de hipófise de carpa e, após 10 horas, 5 UI/g de hCG; 5 fêmeas receberam dose única de solução salina a 0,9%. Cerca de 10 horas após a última aplicação hormonal, 43 fêmeas responderam positivamente aos tratamentos hormonais liberando óvulos por extrusão. A distribuição de freqüência porcentual dos diâmetros dos ovócitos da amostra inicial apresentou tendência unimodal, com moda em 1250 µm. Entre os hormônios testados, o mais eficiente foi o hCG, em dose única, e o menos eficiente, o de hipófise de carpa, com aplicação de duas doses. Os machos receberam dose única de 3 UI de hCG/g. Cada fêmea liberou, em média, 24.690 óvulos, que, após a fertilização e hidratação, se apresentaram esféricos, demersais e não adesivos, com diâmetro médio de 3785 a 3900 µm, grande espaço perivitelínico e córion resistente. A taxa de fertilização oscilou entre 20 e 96% e a de eclosão, entre 0 e 85%. A temperatura da água foi de 26ºC ± 1ºC.

One-step immunoaffinity purification and partial characterization of hypophyseal growth hormone from the African catfish, Clarias gariepinus (Burchell)

Growth hormone (GH) was purified from African catfish (Clarias gariepinus) pituitary extracts in a single step by use of immunoaffinity chromatography. A monoclonal antibody to chicken GH, which labels the catfish hypophyseal somatotropes in immunocytochemistry, was coupled to CNBr-activated Sepharose, and crude alkaline pituitary extracts were run over the immunoadsorbent. Reversed-phase high-performance liquid chromatography analysis of the eluted material suggested heterogeneity, whereas silver staining upon SDS-polyacrylamide gel electrophoresis showed one single band with an estimated molecular weight between 22,000 and 23,000 Da. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of the same preparation revealed the presence of several components with molecular weights ranging from 20,170 to 20,900 Da. The amino terminus of the protein was homogeneous, and the first 50 residues matched the proposed sequence of GH from two other siluran species (Ictalurus punctatus and Pangasius pangasius), except for one substitution at position 3. These data unequivocally confirm the identity of the purified molecule as suggested by immunochemical evidence. The bioactivity of the GH preparation was demonstrated by the short-term effect of GH on T3 plasma levels in juvenile catfish.

The effect of type and number of fsh injections on superovulation in ewes

One of the major limiting factors in practical exploitation of embryo transfer is the lack of a predictable and reliable supply of embryos on a regular basis. Superovulation requires the stimulation of significantly increased numbers of pre-ovulatory follicles by the administration of gonadotrophins mimicking the effect of follicle stimulating hormone (FSH). Ewes can be effectively superovulated using gonadotrophins given towards the end of a 12 to 14-day progestagen treatment, initiated without reference to the stage of the oestrous cycle (Boland et al., 1983). However, as in cattle (Goulding et al., 1991) there is a large variation in the follicular and ovulatory response in sheep. Although crude horse pituitary extracts will induce superovulation effectively in sheep, the lack of availability means that they are rarely used. The LH content in commercial FSH preparations has been indicated as contributing to some of the variation in the yield of transferable embryos in cattle following superovulation (Murphy et al., 1984). Recent preliminary data from this laboratory indicates that pFSH with a high LH:FSH ratio will induce superovulation in cattle and sheep. However, pFSH is normally given in multiple injections over 3 to 4 days which makes administration difficult. Therefore, an experiment was designed to assess the efficacy of a pFSH preparation with a high LH:FSH ratio to induce superovulation in sheep when given in either 4 or 6 injections. A second experiment compared the use of an ovine and porcine FSH preparation during superovulation in ewes.

Efficacy of human chorionic gonadotropin (hCG) and crude pituitary extract of fish and frog in oocyte maturation and ovulation in African catfish, Clarias gariepinus Burchell, 1822 and Clarias anguillaris L., 1762

Abstract. The African catfish, Clarias gariepinus Burchell and Clarias anguillaris L., were induced to ovulate in aquaria by the administration of human chorionic gonadotropin (hCG) and pituitary extracts of Clarias albopunctatus (Nichols & Lamonte) and frog, Rana elegans. For final maturation and ovulation in both species of Clarias, the total dosage of each hormone was inversely proportional to the initial oocyte diameters of the recipient females. The time of ovulation after the last injection (latent period) was significantly shorter (11–13h) in females with large oocyte diameters (>920μm) than in those whose mean oocyte diameters were less than 920 μm (13–16h) (P < 0·05). The mean dosage of each test hormone required to induce ovulation was lower in females with large oocyte diameters than in those with smaller oocyte diameters (<920μm). The mean percentage hatch did not depend significantly on the nature of the treatment (P > 0μ05) and was about 86%. Clarias albopunclatus and R. elegans, which are economically unimportant and abundant in Anambra River basin, Nigeria, could be used as effective sources of hypophyseal factors in Clarias breeding programmes.

Development of homologous radioimmunoassays for equine growth hormone and equine prolactin and their application to the detection of circulating levels of hormone in horse plasma

Highly purified and well-characterised preparations of equine prolactin and growth hormone from equine pituitary glands were employed to set up highly sensitive and specific homologous radioimmunoassays (RIA) for the measurement of hormone in horse plasma. The limit of sensitivity of the GH RIA was 1.2 ng/ml with mean intra- and inter-assay coefficients of variation (CV) of 6.6 and 10%, respectively. The sensitivity of the equine prolactin (ePRL) RIA was 0.5 ng/ml with mean intra and inter-assay CV of 9.1 and 15.6%, respectively. Dose-response curves of a crude pituitary gland extract and plasma samples collected from a mare and foal were parallel to the standards and the PRL RIA was clinically validated by administration of thyrotropin-releasing hormone (TRH). Plasma samples taken at 15 min intervals over 24 h from lactating mares gave 24 h mean GH values in the range 5.5 to 7.95 ng/ml. Large intermittent elevations of GH activity were detected. The mean 24 h PRL concentrations were between 3.2-10.4 ng/ml in the lactating animals, with higher concentrations earlier in lactation. Long episodic bursts of PRL were detected.

Molecular Biological Studies on Animal Growth Hormones

AbstractThe pituitary growth hormone (GH) from various vertebrate species could be purified from crude pituitary extracts by a single‐step HPLC using a reverse‐phase C18 column. The same procedure was also useful for peptide mapping of proteins. Pharmacokinetic analysis of porcine GH revealed that it circulated in plasma with a half‐life of 2 h and that most injected GH was confined to blood and probably lymph, with a total body clearance of porcine GH around 8 ± 3 mL h−1 kg−1. Several GH have been sequenced by using cloning of their cDNA. The comparative analysis of these cDNA reveals the conserved structural characteristics for all vertebrate GH: 1. There are 2 disulfide bonds in the single polypeptide chain of the GH molecule which are supposedly necessary to maintain the native conformation of the hormone. 2. The invariant residues are predominantly located within the α‐helices which are also necessary to maintain the structural integrity but may not be required for species specificity. 3. The putative signal peptides of various GH deduced from the cDNA sequences show the general consensus pattern of hydrophobicity but exhibit no obvious sequence homology. These characteristics are in agreement with other signal peptides of most secretory proteins. A high‐level expression of porcine GH in E. coli was achieved by using some combination of promoter and transcriptional terminator. The expressed 22‐kDa GH was immunoreactive to the specific GH antibody and showed expected partial N‐terminal amino‐acid sequence.

Purification of tilapia thyrotropin from a crude pituitary homogenate by immunoaffinity chromatography using a matrix of antibodies against porcine follicle-stimulating hormone

An immunoadsorbent matrix using antibodies against porcine follicle-stimulating hormone (pFSH), a high heterothyrotropic stimulant in tilapia, was used to purify tilapia thyrotropic hormone (t-TSH) from crude pituitary extracts. A homologous bioassay monitored TSH bioactivity during the purification. Thyroid hormones (thyroxine, T 4; triiodothyronine, T 3; and reverse triiodothyronine, rT 3) and testosterone were measured in vivo in Tilapia nilotica. TSH activity eluted as one major peak at pH 2.8 using a PBS-glycine buffer. The TSH fraction increased plasma T 4 and plasma rT 3. The potency of tTSH was comparable to that of pituitary extract or its Con A II fraction; however, pFSH was a stronger thyroid stimulant. tTSH had no effect on plasma T 3 levels and was free of gonadotropic activity, as indicated by its failure to alter plasma testosterone concentrations. Chromatographic and electrophoretic analyses demonstrated a high degree of purity. Like other vertebrate TSHs, the tTSH appeared to have a subunit structure with a possible microgeneity in one subunit.

Production of monoclonal antibodies against the N-terminal glycopeptide of porcine pro-opiomelanocortin: their use for solid-phase radioimmunoassay, western blotting, and immunogold cytochemistry

We have prepared two monoclonal antibodies for the N-terminal glycopeptide of pro-opiomelanocortin 1-77 (N-POMC(1-77)) purified from porcine pituitaries. Antibody 1-244 recognizes an epitope located within the gamma 3-melanotropin (gamma 3-MSH or POMC(51-77)) sequence, whereas antibody 2-197 binds specifically to a determinant in the 1-49 region of N-POMC. These monoclonal antibodies were used to construct a two-site solid-phase radioimmunoassay that can detect as little as 50 pg of N-POMC(1-77). The assay is linear between 0.5 and 5 ng of porcine peptide and recognizes equally well the homologous peptides purified from human and bovine pituitaries. The assay has been used to analyze reversed-phase high pressure liquid chromatography fractions of crude bovine pituitary extracts and detected a peptide with chromatographic properties identical to those of N-POMC(1-77). When used to stain immunoblots of bovine intermediate pituitary extracts, both the 2-197 and 1-244 antibodies could recognize a major peptide comigrating with purified N-POMC(1-77). In addition, antibody 2-197 also detected a peptide with a mobility similar to that of standard N-POMC(1-49). When used in conjunction with a second anti-mouse antibody coupled to colloidal gold particles, antibody 2-197 stained N-POMC immunoreactive material located in granules in thin sections of pituitary.

Successful culture of adult human melanocytes obtained from normal and vitiligo donors.

The development of growth conditions for human melanocytes from uninvolved skin from vitiligo patients and age-matched normal adults is a prerequisite to understanding the etiology of this pigmentary disorder. By using new growth conditions, pure melanocyte cultures were prepared from normal adults and the pigmented skin of vitiligo donors. Both cell types grew without a lag period and were maintained for more than six months (4-8 passages). The cultures could be expanded from several thousand melanocytes in the original cell suspension to several million cells (2-7 x 10(6] in pure culture. To obtain these results, the current standard conditions for the culture of fetal melanocytes were substantially modified. MEM-S medium was less satisfactory than MCDB-153. Adult normal and vitiligo cells also required the presence of exogenous catalase (20 micrograms/ml) during isolation and primary seeding. Thereafter, this enzyme was not necessary. Melanocytes grew best and gave the highest yields if the concentrations of both calcium (200 microM) and the phorbol ester 12-0-tetradecanoylphorbol-13-acetate (TPA) were low (4-8 nM). Other growth factors included in the MCDB-153 media were bFGF, crude bovine pituitary extract, insulin, transferrin, hydrocortisone, 5% FCS, and the antioxidant alpha-tocopherol. Cholera toxin and isobutylmethylxanthine (IBMX) were omitted from the MCDB-153 growth medium because they slowed down growth even at very low concentrations. The results indicate adult and vitiligo melanocytes can be cultured. Preliminary studies of the normal and vitiligo cells indicate that vitiligo melanocytes retain some of the ultrastructural abnormalities observed in skin even when grown in culture.

Induced Spawning of Spotted Seatrout with Selected Hormone Preparations

Abstract Strip-spawning trials were performed with spotted seatrout (Cynoscion nebulosus) after females received injections of 250, 500, and 1,100 IU human chorionic gonadotropin (HCG)/kg body weight (BW); 10, 50, and 100 mg carp pituitary extract/kg BW; 10, 50, and 100 mg salmon pituitary extract/kg BW; and a crude spotted seatrout pituitary extract administered on the basis of two, four, and six pituitaries per fish. Each hormone dose was administered to three females on each of four trial dates. All hormone types induced ovulation. The percentage of fish induced to ovulate by each hormone generally increased with dosage. Only HCG administered at 1,100 IU/kg BW caused ovulation in all fish treated. The different hormone preparations did not significantly affect fertilization once ovulation occurred (P > 0.05).

Plasma clearance in the rat of the LH bioactivity of two human LH standards of differing molecular composition.

The LH biological potency of the International Reference Preparation (IRP) of Human Pituitary LH for Immunoassay (IRP 68/40) relative to that of the 2nd IRP of Human Pituitary FSH and LH for Bioassay (IRP 78/549) is markedly greater when estimated by in-vitro interstitial cell testosterone production (TICT) bioassay than by in-vivo bioassay, and by the 4-h ovarian ascorbate depletion (OAAD) assay than by the 4-day seminal vesicle weight gain assay. Other preparations of human LH which, like IRP 68/40, were highly purified, showed a similar spectrum of bioactivity in these assay systems and also contained a higher proportion of more basic LH isoforms than are found in crude pituitary extracts such as IRP 78/549. In an attempt to explain these differences, a comparison was made of the plasma survival in rats of the LH bioactivity (by TICT assay) of these two preparations. Contrary to expectation, their relative plasma clearance rates over a 4-h period did not account for their differing bioactivities. The plasma half-life of the LH bioactivity (with 95% confidence limits) was estimated to be 42.4 (35.3-49.5) min for IRP 68/40 and 41.3 (31.5-51.0) min for IRP 78/549. Furthermore the time-course of action in vivo of IRP 78/549 did not appear to be more prolonged than that of IRP 68/40. Thus their plasma testosterone responses during the course of these 4-h plasma clearance studies were similar, and estimates of the LH potency of IRP 68/40 relative to that of IRP 78/549 were no greater by 2-h than by 4-h OAAD assay.(ABSTRACT TRUNCATED AT 250 WORDS)