Hemodynamics of the corpus luteum in mares during experimentally impaired luteogenesis and partial luteolysis.

The aim of the current project was to characterize the luteal vascularity and the plasma concentrations of progesterone (P4), prolactin (PRL) and 13,14-dihydro-15-keto-PGF2α (PGFM) in mares with luteal disturbances during early and mid-diestrus. In Experiment 1, twenty-one mares were treated with 2 mL of 0.9% NaCl, or 1 mg Dinoprost, or 10 mg Dinoprost on day two after ovulation (Control-D2, 1/10PGF-D2 and PGF-D2 groups, respectively; n = 7 mares/group). In Experiment 2, similar treatments were performed eight days post-ovulation using a different cohort of 21 mares (Control-D8, 1/10PGF-D8 and PGF-D8 groups, respectively; n = 7 mares/group). Blood samples were collected hourly and power-Doppler examinations of the corpus luteum (CL) were performed every 6 h from H0 (moment immediately before treatment) to H48. Data collection was also done once a day from D0 (day of ovulation) to D20. In Experiment 1, the PGF-D2 and 1/10PGF-D2 groups had lower increase of plasma concentration of P4 until H48 and reduced maximum P4 concentrations on D8-D11 than mares from the Control-D2 group. However, no differences among groups were detected for luteal vascularity during early and mid-diestrus. In Experiment 2, complete and partial luteolysis were detected in mares from the PGF-D8 and 1/10PGF-D8 groups, respectively. Luteal vascularity and plasma P4 concentrations differed among Control-D8, PGF-D8 and 1/10PGF-D8 groups on H48. Partially regressed CLs (1/10PGF-D8 group) generated more Doppler signals than completed regressed CLs (PGF-D8 group) between D10 and D13. In both experiments, a transient increase in PRL activity was observed in parallel to the PGFM pulse in mares receiving 1 or 10 mg Dinoprost. The use of prostaglandin on D2 at conventional or 1/10 of the dose impaired the luteal development in mares. Moreover, the low dose of prostaglandin lead to partial regression of mature CLs. The blood supply was reduced in partially regressed CLs, but not in CLs undergoing impaired luteogenesis.

Changes in plasma melanocyte-stimulating hormone, ACTH, prolactin, GH, LH, FSH, and thyroid-stimulating hormone in response to injection of sulpiride, thyrotropin-releasing hormone, or vehicle in insulin-sensitive and -insensitive mares.

Six insulin-sensitive and 6 insulin-insensitive mares were used in a replicated 3 by 3 Latin square design to determine the pituitary hormonal responses (compared with vehicle) to sulpiride and thyrotropin-releasing hormone (TRH), 2 compounds commonly used to diagnose pituitary pars intermedia dysfunction (PPID) in horses. Mares were classified as insulin sensitive or insensitive by their previous glucose responses to direct injection of human recombinant insulin. Treatment days were February 25, 2012, and March 10 and 24, 2012. Treatments were sulpiride (racemic mixture, 0.01 mg/kg BW), TRH (0.002 mg/kg BW), and vehicle (saline, 0.01 mL/kg BW) administered intravenously. Blood samples were collected via jugular catheters at -10, 0, 5, 10, 20, 30, 45, 60, 90, and 120 min relative to treatment injection. Plasma ACTH concentrations were variable and were not affected by treatment or insulin sensitivity category. Plasma melanocyte-stimulating hormone (MSH) concentrations responded (P < 0.01) to both sulpiride and TRH injection and were greater (P < 0.05) in insulin-insensitive mares than in sensitive mares. Plasma prolactin concentrations responded (P < 0.01) to both sulpiride and TRH injection, and the response was greater (P < 0.05) for sulpiride; no effect of insulin sensitivity was observed. Plasma thyroid-stimulating hormone (TSH) concentrations responded (P < 0.01) to TRH injection only and were higher (P < 0.05) in insulin-sensitive mares in almost all time periods. Plasma LH and FSH concentrations varied with time (P < 0.05), particularly in the first week of the experiment, but were not affected by treatment or insulin sensitivity category. Plasma GH concentrations were affected (P < 0.05) only by day of treatment. The greater MSH responses to sulpiride and TRH in insulin-insensitive mares were similar to, but not as exaggerated as, those observed by others for PPID horses. In addition, the reduced TSH concentrations in insulin-insensitive mares are consistent with our previous observation of elevated plasma triiodothyronine concentrations in hyperleptinemic horses (later shown to be insulin insensitive as well).

Relationships of occupational and non-occupational physical activity to abdominal obesity.

HYPOTHESIS: Physically active occupations may protect against the risk of abdominal obesity. OBJECTIVES: This study assessed the interaction between non-occupational physical activity (NOA) (leisure-time, transport and domestic activity) and occupational activity (OA) in relation to abdominal obesity. METHODS: A total of 3539 adults over the age of 20, with no work limitations, employed in one of the 17 occupations classified as low OA (LOA) or high OA (HOA) were identified in the 1999-2004 National Health and Nutrition Examination Survey. Waist circumference (WC) was used to categorize individuals into either non-obese or abdominally obese (WC>88 cm in women and >102 cm in men) categories. NOA was divided into three categories based upon physical activity guidelines: (1) no NOA; (2) insufficient NOA; and (3) sufficient NOA. Logistic regression was used to examine possible associations between NOA, OA and abdominal obesity. RESULTS: In those who are sedentary outside of work, a high-activity occupation reduces the odds risk ratio of being categorized with abdominal obesity to 0.37 in comparison with those who work in low-activity occupations. For people working in low-activity occupations, there was a clear association with activity outside of work and the odds risk ratio of being categorized with abdominal obesity. In these adults, a reduced odds ratio was found only among those who met the physical activity guidelines through NOA (odds ratio=0.55; 95% confidence interval (CI)=0.40-0.75). CONCLUSION: HOA is associated with a reduced risk of abdominal obesity. Thus, it is important to include OA in studies seeking to understand the association between physical activity and abdominal adiposity.

Fibroblast growth factor-18 stimulates chondrogenesis and cartilage repair in a rat model of injury-induced osteoarthritis.

OBJECTIVE: Osteoarthritis (OA) is the most common form of arthritis and a primary cause of disability, however, there are no treatments that can slow disease progression or repair damaged joint cartilage. Fibroblast growth factor-18 (FGF18) has been reported to have significant anabolic effects on cartilage. We therefore examined its effects on repair of cartilage damage in a rat meniscal tear model of OA. DESIGN: Surgical damage to the meniscus in rats leads to joint instability and significant damage to the articular cartilage at 3 weeks post-surgery. At this time, animals received bi-weekly intra-articular injections of FGF18 for 3 weeks, and the knee joints were then harvested for histologic examination. RESULTS: FGF18-induced dose-dependent increases in cartilage thickness of the tibial plateau, due to new cartilage formation at the articular surface and the joint periphery. The generation of new cartilage resulted in significant reductions in cartilage degeneration scores. The highest dose of FGF18 also induced an increase in chondrophyte size and increased remodeling of the subchondral bone. CONCLUSIONS: The results of this study demonstrate that FGF18 can stimulate repair of damaged cartilage in a setting of rapidly progressive OA in rats.

Concentrations of nitric oxide in equine preovulatory follicles before and after administration of human chorionic gonadotropin.

In the present study, follicular fluids of estrous mares treated with saline solution (Control) or nitric oxide synthase (NOS) inhibitors were analyzed for nitric oxide (NO), estradiol-17beta (E2) and progesterone (P4) concentrations before and 36h after administration of human chorionic gonadotropin (hCG). Follicular fluids obtained before (0h) hCG administration from control mares had lower concentrations of NO than those obtained 36h after administration of hCG (58.3+/-17.8 micromol versus 340.4+/-57.7 micromol; P<0.05). A similar pattern was also noted for intrafollicular P4 in control mares, which had lower concentrations of intrafollicular P4 before hCG than 36h post-hCG administration (P<0.05). As expected, E2 concentrations of control follicles sampled before hCG administration were higher than those sampled 36h post-hCG administration (P<0.05). However, the E2 concentrations in follicles of mares treated with the NOS inhibitors N(omega)-nitro-L-arginine methyl ester (L-NAME) or aminoguanidine (AG) did not decrease after hCG administration, unlike those in control mares (P>0.10). In addition, mares treated with NOS inhibitors had lower intrafollicular concentrations of NO and P4 than control mares, both before and after hCG administration (P<0.05). Increased intrafollicular concentrations of NO in control, hCG-stimulated mares provide evidence for the presence of an NO-generating system in the equine preovulatory follicle that is likely upregulated following administration of hCG.

Effects of deslorelin acetate implants in horses: single implants in stallions and steroid-treated geldings and multiple implants in mares.

Three experiments were performed to test the following hypotheses: 1) stallions and/or progesterone-estradiol-treated geldings could serve as models for the effects of a single implant of the GnRH analog, deslorelin acetate, on LH and FSH secretion by mares; and 2) multiple implants of deslorelin acetate could be used as a means of inducing ovarian atrophy in mares for future study of the mechanisms involved in the atrophy observed in some mares after a single implant. In Exp. 1, nine light horse stallions received either a single deslorelin implant (n = 5) or a sham injection (n = 4) on d 0. In Exp. 2, 12 geldings received daily injections of progesterone on d -20 through -4, followed by twice-daily injections of estradiol on d -2 to 0. On the morning of d 0, geldings received either a single deslorelin implant (n = 6) or a sham injection (n = 6). Daily injections of progesterone were resumed on d 2 through 15. In Exp. 1, plasma LH and FSH were elevated (P < 0.05) in the treatment group relative to controls at 4, 8, and 12 h after implant insertion. In the treated stallions, FSH was decreased (P < 0.05) on d 3 to 13, and LH was decreased on d 6 to 13. In Exp. 2, plasma LH and FSH were elevated (P < 0.05) at 4,8, and 12 h after deslorelin implant insertion. Plasma LH was suppressed (P < 0.05) below controls on d 2 to 7, 9, and 11 to 15; plasma FSH was suppressed (P < 0.05) on d 4 to 15. In Exp. 3, 21 mares were used to determine whether multiple doses of deslorelin would cause ovarian atrophy. Mares received one of three treatments: 1) sham injections; 2) three implants on the first day; or 3) one implant per day for 3 d (n = 7 per group). Treatment with multiple implants increased (P < 0.05) the interovulatory interval by 14.8 d and suppressed (P < 0.01) LH and FSH concentrations for approximately 25 d; no mare exhibited ovarian atrophy. In conclusion, after an initial short-term increase in LH and FSH secretion, deslorelin implants caused long-term suppression of both gonadotropins in stallions as well as in geldings treated with progesterone and estradiol to mimic the estrous cycle. It is likely that either of these models may be useful for further study of this suppression in horses. Although multiple implants in mares suppressed gonadotropin secretion longer than a single implant, the lack of ovarian atrophy indicates that the atrophy observed after a single implant in previous experiments was likely due to the susceptibility of individual mares.

Pituitary responsiveness to GnRH in mares following deslorelin acetate implantation to hasten ovulation.

The present experiment characterized the pituitary responsiveness to exogenous GnRH in the first 10 d after ovulation following commercially available deslorelin acetate implantation at the normal dosage for hastening ovulation in mares. Twelve mature, cyclic mares were assessed daily for estrus and three times weekly for ovarian activity starting May 1. Mares achieving a follicle at least 25 mm in diameter or showing signs of estrus were checked daily thereafter for ovarian characteristics. When a follicle >30 mm was detected, mares were administered either a single deslorelin acetate implant or a sham injection and then assessed daily for ovulation. On d 1, 4, 7, and 10 following ovulation, each mare was challenged i.v. with 50 microg GnRH, and blood samples were collected to characterize the LH and FSH responses. The size of the largest follicle on the day of treatment did not differ (P = 0.89) between groups. The number of days from treatment to ovulation was shorter (P < 0.001) by 2.0 d for the treated mares indicating a hastening of ovulation. The size of the largest follicle present on the days of GnRH challenge was larger in the treated mares on d 1 (P = 0.007) but smaller on d 10 (P = 0.02). In addition, the interovulatory interval was longer (P = 0.036) in the treated mares relative to controls by 4.4 d. Concentrations of FSH in plasma of the treated mares were lower (P < 0.05) than control concentrations from d 3 to 12; LH concentrations in the treated mares were lower (P < 0.05) relative to controls on d 0 to 5, d 7, and again on d 20 to 23. Progesterone values were the same (P = 0.99) for both groups from 2 d before ovulation though d 23. There was an interaction of treatment, day, and time of sampling (P < 0.001) for LH and FSH concentrations after injection of GnRH. Both the LH and FSH responses were suppressed (P < 0.009) in the treated mares relative to controls on d 1, 4, and 7; by d 10, the responses of the two groups were equivalent. In conclusion, deslorelin administration in this manner increased the interovulatory interval, consistently suppressed plasma LH and FSH concentrations, and resulted in a complete lack of responsiveness of LH and FSH to GnRH stimulation at the dose used during the first 7 d after the induced ovulation. Together, these results are consistent with a temporary down-regulation of the pituitary gland in response to deslorelin administered in this manner.

The relationship between body condition, leptin, and reproductive and hormonal characteristics of mares during the seasonal anovulatory period.

An experiment was conducted to determine the effects of high vs low body condition scores (BCS) produced by restricted feeding on reproductive characteristics, hormonal secretion, and leptin concentrations in mares during the autumnal transition and winter anovulatory period. Mares with BCS of 6.5 to 8.0 were maintained on pasture and/or grass hay, and starting in September, were full fed or restricted to produce BCS of 7.5 to 8.5 (high) or 3.0 to 3.5 (low) by December. All but one mare with high BCS continued to ovulate or have follicular activity during the winter, whereas mares with low BCS went reproductively quiescent. Plasma leptin concentrations varied widely before the onset of restriction, even though all mares were in good body condition. During the experiment, leptin concentrations gradually decreased (P < 0.0001) over time in both groups, but were higher (P < 0.009) in mares with high vs low BCS after 6 wk of restriction, regardless of initial concentration. No differences (P > 0.1) between groups were detected for plasma concentrations of LH, FSH, TSH, GH, glucose, or insulin in samples collected weekly; in contrast, plasma prolactin concentrations were higher (P < 0.02) in mares with high BCS, but also decreased over time (P < 0.008). Plasma IGF-I concentrations tended (P = 0.1) to be greater in mares with high vs low BCS. The prolactin response to sulpiride injection on January 7 did not differ (P > 0.1) between groups. During 12 h of frequent blood sampling on January 12, LH concentrations were higher (P < 0.0001), whereas GH concentrations (P < 0.0001) and response to secretagogue (EP51389; P < 0.03) were lower in mares with high BCS. On January 19, the LH response to GnRH was higher (P < 0.02) in mares with high BCS; the prolactin response to TRH also was higher (P < 0.01) in mares with high BCS. In conclusion, nutrient restriction resulting in low BCS in mares resulted in a profound seasonal anovulatory period that was accompanied by lower leptin, IGF-I, and prolactin concentrations. All but one mare with high BCS continued to cycle throughout the winter or had significant follicular activity on the ovaries. Although leptin concentrations on average are very low in mares with low BCS and higher in well-fed mares, there is a wide variation in concentrations among well-fed mares, indicating that some other factor(s) may determine leptin concentrations under conditions of high BCS.

Administration of sulpiride to anovulatory mares in winter: effects on prolactin and gonadotropin concentrations, ovarian activity, ovulation and hair shedding.

Sixteen seasonally anovulatory mares were randomly allotted to two groups and injected daily with either sulpiride (1 mg/kg body weight) or vehicle from 14 January to 14 February. Sulpiride administration increased daily plasma prolactin concentrations (P < 0.05), although the prolactin response during the 6 h following sulpiride injections decreased markedly from the 1st to the 6th day of treatment (treatment by day, P < 0.0001). Plasma concentrations of LH and FSH were not affected by treatment (P > 0.1). Injection of GnRH and TRH on 15 February showed that the response of plasma prolactin to secretagogue was increased in sulpiride-treated mares (P < 0.005), while there was no effect (P > 0.1) of sulpiride treatment on the response of LH or FSH. Both treatment groups had similar changes in numbers of follicles 10-19 and > or = 20 mm during the experiment (P > 0.1). Similarly, the mean change in maximal follicular size was not affected by treatment (P > 0.9). No mare ovulated during the study, and plasma progesterone concentrations were similar in both groups (P > 0.1), always at levels < 1 ng/ml. Hairshedding increased with time in all mares (P < 0.001) and was increased by sulpiride injections (P = 0.09). It was concluded that sulpiride administration to seasonally anovulatory mares under the conditions of our experiment increased daily plasma prolactin levels but did not stimulate gonadotropin secretion or ovarian activity.

Fibroblast growth factor-18 is a trophic factor for mature chondrocytes and their progenitors.

OBJECTIVE: The aim of this study was to examine the effects of recombinant human Fgf18 on chondrocyte proliferation and matrix production in vivo and in vitro. In addition, the expressions of Fgf18 and Fgf receptors (Fgfr) in adult human articular cartilage were examined. METHODS: Adenovirus-mediated transfer of Fgf18 into murine pinnae and addition of FGF18 to primary cultures of adult articular chondrocytes were used to assess the effects of FGF18 on chondrocytes. In situ hybridization was used to examine the expression of Fgf18 and Fgfr s in adult human articular cartilage. RESULTS: Expression of Fgf18 by adenovirus-mediated gene transfer in murine pinnae resulted in a significant increase in chondrocyte number. Chondrocytes were identified by staining with toluidine blue and a monoclonal antibody directed against type II collagen. Fgf18, Fgfr 2-(IIIc), Fgfr 3-(IIIc), and Fgfr 4 mRNAs were detected within these cells by in situ hybridization. The nuclei of the chondrocytes stained with antibodies to PCNA and FGF receptor (FGFR) 2. Addition of FGF18 to the culture media of primary articular chondrocytes increased the proliferation of these cells and increased their production of extracellular matrix. To assess the receptor selectivity of FGF18, BaF3 cells stably expressing the genes for the major splice variants of Fgfr1-3 were used. Proliferation of cells expressing Fgfr 3-(IIIc) or Fgfr 2-(IIIc) was increased by incubation with FGF18. Using FGFR-Fc fusion proteins and BaF3 cells expressing Fgfr 3-(IIIc), only FGFR 3-(IIIc)-Fc, FGFR 2-(IIIc)-Fc or FGFR 4-Fc reduced FGF18-mediated cell proliferation. Expression of Fgf18, Fgfr 3-(IIIc) and Fgfr 2-(IIIc) mRNAs was localized to chondrocytes of human articular cartilage by in situ hybridization. CONCLUSION: These data demonstrate that Fgf18 can act as a trophic factor for elastic chondrocytes and their progenitors in vivo and articular chondrocytes cultured in vitro. Expression of Fgf18 and the genes for two of its receptors in chondrocytes suggests that Fgf18 may play an autocrine role in the biology of normal articular cartilage.

Growth hormone response to a novel growth hormone-releasing tripeptide in horses: interaction with gonadotropin-releasing hormone, thyrotropin-releasing hormone, and sulpiride.

A series of experiments was performed to determine the factor(s) responsible for an apparent inhibition of GH secretion in mares administered the GH secretagogue EP51389 in combination with GnRH, thyrotropin-releasing hormone (TRH), and sulpiride. Experiment 1 tested the repeatability of the original observation: 10 mares received EP51389 at 10 microg/kg BW; five received TRH (10 microg/kg BW), GnRH (1 microg/kg BW), and sulpiride (100 microg/kg BW) immediately before EP51389, and five received saline. The mixture of TRH, GnRH, and sulpiride reduced (P = 0.0034) the GH response to EP51389, confirming the inhibitory effects. Experiment 2 tested the hypothesis that sulpiride, a dopamine antagonist, was the inhibitory agent. Twelve mares received EP51389 as in Exp. 1; six received sulpiride before EP51389 and six received saline. The GH responses in the two groups were similar (P > 0.1), indicating that sulpiride was not the inhibitory factor. Experiment 3 tested the effects of TRH and(or) GnRH in a 2 x 2 factorial arrangement of treatments. Three mares each received saline, TRH, GnRH, or the combination before EP51389 injection. There was a reduction (P < 0.0001) in GH response in mares receiving TRH, whereas GnRH had no effect (P > 0.1). Given those results, Exp. 4 was conducted to confirm that TRH was inhibitory in vivo as opposed to some unknown chemical interaction of the two compounds in the injection solution. Twenty mares received TRH or saline and(or) EP51389 or saline in a 2 x 2 factorial arrangement of treatments. Injections were given separately so that the two secretagogues never came in contact before injection. Again, TRH reduced (P < 0.0001) the GH response to EP51389. In addition, TRH and EP51389 each resulted in a temporary increase in cortisol concentrations. Experiment 5 tested whether TRH would alter the GH response to GHRH itself. Twelve mares received porcine GHRH at 0.4 microg/kg BW; six received TRH prior to GHRH and six received saline. After adjustment for pretreatment differences between groups, the GHRH-induced GH response was completely inhibited (P = 0.068) by TRH. Exp. 6 was a repeat of Exp. 5, except geldings were used (five per group). Again, pretreatment with TRH inhibited (P < 0.0001) the GH response to GHRH. In conclusion, TRH inhibits the GH response not only to EP51389 but also to GHRH in horses, and in addition to its known secretagogue action on prolactin and TSH it may also stimulate ACTH at the dosage used in these experiments.

Daily treatment of growing foals with equine somatotropin: pathologic and endocrinologic assessments at necropsy and residual effects in live animals.

This experiment assessed the effects of 12 mo of daily treatment of young horses with recombinant equine somatotropin (eST) on 1) carcass and internal organ traits at necropsy and 2) residual effects in live horses for 60 d after cessation of treatment. Seven horses received eST daily at 20 microg/kg BW; seven others received vehicle (controls). Four horses from each group were killed at the end of treatment. There were few effects of eST treatment on hematologic assessments or histopathologic evaluations of internal organs. Treatment with eST increased the weights of the right adrenal gland (P = 0.090), left (P = 0.085) and right (P = 0.013) kidneys, liver (P = 0.012), tended to inrease the weights of pancreas (P = 0.082), spleen (P = 0.008), and heart (P = 0.102), and decreased (P = 0.032) somatotropin (ST) content in the adenohypophysis. Loin-eye area at the 10th rib was also greater (P = 0.01) in eST-treated horses than in controls. There was no difference (P > 0.15) between groups in left adrenal, brain, parathyroid glands, or thyroid gland weights or in 10th-rib fat thickness. In the remaining two control and three eST-treated horses (one control horse died), plasma IGF-I concentrations were higher (P = 0.001) in treated animals through d 6 after cessation of treatment and then dropped precipitously. Insulin concentrations in treated animals tended to be elevated (P = 0.08) only on d 0. There was a treatment x day interaction (P = 0.04) for plasma urea nitrogen levels, which increased in treated horses. A decrease (P < 0.05) in BW in the treated animals was observed by 21 d after treatment. There was no difference (P > 0.15) in insulin or glucose response to glucose tolerance tests given on d 0 through 60 after cessation of treatment. Overall ST response to secretagogue was reduced (P < 0.05) in eST-treated horses compared with controls. In summary, long-term treatment of growing horses with eST decreased endogenous ST response to secretagogue and increased plasma IGF-I concentrations and many internal organ weights but had little effect on hematologic or histopathologic characteristics at necropsy. The effects on IGF-I concentrations were lost within 6 d, and BW in treated horses decreased within 3 wk after cessation of treatment.

Responses of seasonally anovulatory mares to daily administration of thyrotropin-releasing hormone and(or) gonadotropin-releasing hormone analog.

Seventeen seasonally anovulatory light horse mares were treated daily, starting January 5 (d 1), for 28 d with GnRH analog (GnRH-A; 50 ng/kg BW) and(or) thyrotropin-releasing hormone (TRH; 5 microg/kg BW) in a 2 x 2 factorial arrangement of treatments to test the hypothesis that combined treatment may stimulate follicular growth and development. Ovaries were examined via ultrasonography and jugular blood samples were collected every 3 d. Frequent blood samples were collected after treatment injections on d 1, 2, 4, 7, 11, 16, and 22; on d 29, all mares received an i.v. mixture of GnRH, TRH, sulpiride, and EP51389 (a growth hormone secretagogue) to assess pituitary responsiveness. No consistent effects (P > 0.1) of treatment were observed for plasma LH, FSH, prolactin, or thyroxine concentrations in samples collected every 3 d. The only effect on ovarian follicle numbers was a reduction in number of follicles 11 to 19 mm in diameter due to TRH treatment (P = 0.029). No mare ovulated during treatment. On the days of frequent sampling, mean LH (P = 0.0001) and FSH (P = 0.001) concentrations were higher in mares receiving GnRH-A and tended to increase from d 1 through 7. In contrast, mean prolactin (P = 0.001) and thyroid-stimulating hormone (P = 0.0001) concentrations were high in mares receiving TRH on d 1 but rapidly decreased thereafter. When mares were administered the secretagogue mixture on d 29, the LH response was greater (P = 0.0002) in mares that had previously received GnRH-A but the FSH response was not affected (P > 0.1); the prolactin response was greater (P = 0.014) and the TSH response was smaller (P = 0.0005) in mares that had previously received TRH. Surprisingly, an immediate growth hormone response to EP51389 was absent in all mares. In conclusion, daily GnRH-A treatment stimulated plasma LH and FSH concentrations immediately after injection; although no long-term elevation in preinjection concentrations was achieved, the responses gradually increased over time, indicating a stimulation of gonadotropin production and storage. Daily treatment with TRH stimulated plasma TSH and prolactin concentrations, but the response diminished rapidly and was minimal within a few days, indicating a depletion of pituitary stores and little or no stimulation of production. There was no beneficial effect of adding TRH treatment to the daily GnRH-A regimen.

High versus low body condition in mares: interactions with responses to somatotropin, GnRH analog, and dexamethasone.

Mares that had previously been fed to attain body condition scores (BCS) of 7.5 to 8.5 (high) or 3.0 to 3.5 (low) were used to determine the interaction of BCS with the responses to 1) administration of equine somatotropin (eST) daily for 14 d beginning January 20 followed by administration of GnRH analog (GnRHa) daily for 21 d and 2) 4-d treatment with dexamethasone later in the spring when mares in low BCS had begun to ovulate. The majority of mares with high BCS continued to cycle throughout the winter, as evidenced by larger ovaries (P < 0.002), more corpora lutea (P < 0.05), greater progesterone concentrations during eST treatment (P < 0.04), and more (P < 0.05) large- and medium-sized follicles. Treatment with eST alone or in combination with GnRHa had no effect (P > 0.05) on ovarian activity or ovulation. Plasma leptin concentrations were greater (P < 0.002) in mares with high BCS; however, there was no effect (P > 0.10) of eST treatment. Plasma IGF-I concentrations were greater (P < 0.0001) in mares treated with eST compared with mares given vehicle, and mares with high BCS had greater IGF-I (P < 0.02) and LH concentrations (P < 0.02) than mares with low BCS. Plasma leptin concentrations in mares with high BCS were increased (P < 0.001) within 12 h of dexamethasone treatment; the leptin response (P < 0.001) in mares with low BCS was greatly reduced (P < 0.001) and transient. Glucose and insulin concentrations also increased (P < 0.0001) after dexamethasone treatment in both groups, and the magnitude of the response was greater (P < 0.0001) in mares with high BCS than in mares with low BCS. In summary,low BCS in mares was associated with a consistent seasonal anovulatory state that was affected little by eST and GnRHa administration. In contrast, all but one mare with high BCS continued to experience estrous cycles and(or) have abundant follicular activity on their ovaries. The IGF-I response to eST treatment was also reduced in mares with low BCS, as was the basal leptin concentration and leptin response to dexamethasone. Although low BCS and leptin concentrations were associated with inactive ovaries during winter and early spring, mares with low BCS eventually ovulated in April and May while leptin concentrations remained low.

Validity of inspiratory and expiratory methods of measuring gas exchange with a computerized system.

The accuracy of a computerized metabolic system, using inspiratory and expiratory methods of measuring ventilation, was assessed in eight male subjects. Gas exchange was measured at rest and during five stages on a cycle ergometer. Pneumotachometers were placed on the inspired and expired side to measure inspired (VI) and expired ventilation (VE). The devices were connected to two systems sampling expired O(2) and CO(2) from a single mixing chamber. Simultaneously, the criterion (Douglas bag, or DB) method assessed VE and fractions of O(2) and CO(2) in expired gas (FE(O(2)) and FE(CO(2))) for subsequent calculation of O(2) uptake (VO(2)), CO(2) production (VCO(2)), and respiratory exchange ratio. Both systems accurately measured metabolic variables over a wide range of intensities. Though differences were found between the DB and computerized systems for FE(O(2)) (both inspired and expired systems), FE(CO(2)) (expired system only), and VO(2) (inspired system only), the differences were extremely small (FE(O(2)) = 0.0004, FE(CO(2)) = -0.0003, VO(2) = -0.018 l/min). Thus a computerized system, using inspiratory or expiratory configurations, permits extremely precise measurements to be made in a less time-consuming manner than the DB technique.

Relationship of leisure-time physical activity and occupational activity to the prevalence of obesity.

OBJECTIVE: To assess the interaction between leisure-time physical activity (LTPA) and occupational activity (OA) on the prevalence of obesity. DESIGN: Secondary data analysis of a population based cross-sectional US national sample (NHANES III). SUBJECTS: A total of 4889 disease-free, currently employed adults over age 20 y. MEASUREMENTS: Subjects body mass index (BMI) was categorized as (1) obese (BMI> or =30 kg/m(2)), or (2) non-obese (BMI<30 kg/m(2)). LTPA was divided into four categories: (1) no LTPA; (2) irregular LTPA; (3) regular moderate intensity LTPA; and (4) regular vigorous intensity LTPA. OA was grouped as (1) high OA and (2) low OA. Age, gender, race-ethnicity, smoking status, urbanization classification, alcohol consumption and income were statistically controlled. RESULTS: In all, 16.8% (s.e. 0.7) of the total subject population were obese (15.1% (s.e. 1.1) of men and 19.1% (s.e. 1.1) of women). Logistic regression revealed that compared to those who engage in no LTPA and have low levels of OA, the likelihood of being obese is 42% (95% CI 0.35, 0.96) lower for those who engage in no LTPA and have high OA, 48% (95% CI 0.32, 0.83) lower for those who have irregular LTPA and have high levels of OA, and about 50% lower for all those who have regular LTPA through moderate or vigorous activity levels regardless of OA level. CONCLUSION: When considering disease free adults above 20 y of age employed in high and low activity occupations, a high level of occupational activity is associated with a decreased likelihood of being obese.

Luteinizing hormone response to controlled-release deslorelin in estradiol benzoate primed ovariectomized gilts.

Development of a controlled release formulation of gonadotropin releasing hormone that would stimulate a LH surge capable of reducing the time span of ovulations would greatly benefit reproductive management because a single timed insemination could be used. A dose-response study was conducted to determine if Deslorelin, a potent gonadotropin releasing hormone analogue, delivered via the SABER system, a biodegradable controlled release system, would stimulate an ovulatory-like LH surge in the pig. Twenty ovariectomized gilts, approximately 200 d old and 100 kg body weight (BW), received estradiol benzoate (15 microg/kg BW im) and 48 h later, the gilts were given deslorelin at 0, 12.5, 25.0, 50.0 or 100.0 microg im (n = 4 each treatment group). Compared to controls, mean blood deslorelin concentrations were still elevated at 30 h after deslorelin. Mean deslorelin magnitude, area under the curve and duration were sequentially greater (P<0.05) in a dose-dependent sequence. Compared to controls, serum LH concentrations were elevated (P<0.05) for 6 to 12 h after deslorelin. A dose-response relationship was absent for all parameters of LH secretion. Magnitude of the serum LH response was greatest (P<0.05) in the 12.5 microg and 50.0 microg groups, whereas area under the curve was lower (P<0.05) after 25.0 microg of deslorelin than after 12.5, 50.0 and 100.0 microg, which were not different from each other. Thus, no more than 12.5 microg of deslorelin is necessary to obtain maximum LH release in the model studied and doses less than 12.5 microg may also be effective.

Prenatal sonographic detection of congenital hepatic cyst in third trimester after normal second-trimester sonographic examination.

A solitary unilocular hepatic cyst (SUHC) is a rare prenatal or neonatal finding. There are few reports of the prenatal detection of SUHC, and the progression of SUHC in utero is unknown. We present a proven case of SUHC in a fetus detected on a 34-week ultrasound examination following a normal 19-week examination. The cyst was inseparable from the liver and caused some flattening of the liver edge. Prenatal detection of an SUHC inseparable from the liver and appearing in the late second or third trimester should suggest a congenital hepatic cyst.

Immunization against GnRH in male species (comparative aspects).

Active immunization against gonadotropin-releasing hormone (GnRH) was recognized in the 1970s as a potential means by which the reproductive system of mammals might be shut down for various practical and clinical reasons. Numerous studies in males have been performed since that time to determine the applicability of the technique as an alternative to surgical removal of the testes. Reasons for such immunocastration include improvement of meat and carcass characteristics for cattle, sheep, goats, and swine; improvement in feed efficiency relative to castrates in those same species; reduction in male aggressive behavior; reduction in male-associated odors in goats and swine; and fertility neutralization in pet species. Although application as a fertility control agent in men is unlikely, there is renewed interest in active immunization against GnRH as a means of treating prostate cancers and related steroid-dependent pathologies.

Stanniocalcin 2: characterization of the protein and its localization to human pancreatic alpha cells.

Stanniocalcin (STC) is a hormone that was originally identified in fish, where it inhibits calcium uptake by the gills and gut and stimulates phosphate adsorption by the kidney. Recently, two mammalian homologues of stanniocalcin were identified. The first (STC1) shows 61% identity to the fish stanniocalcins and appears to have a function similar to that of the fish stanniocalcins. The second homologue (STC2) is 30-38% identical to the fish stanniocalcins, and is characterized by unique cysteine and histidine motifs that are not found in the other stanniocalcins. We purified both the native hamster and recombinant human STC2 proteins and obtained a partial amino acid sequence of the hamster protein. Both proteins behave as a disulfide bonded homodimer, which undergoes post-translational modification(s). The STC2 gene was localized to human chromosome 5q35. Northern blot analysis revealed that the primary site of human STC2 production is the pancreas, and immunostaining localized the STC2 protein to a subpopulation of cells in the islet. Double immunostaining for STC2 and either insulin or glucagon revealed that STC2 protein is found in the alpha cells, but not the beta cells. We speculate that STC2 may play a role in glucose homeostasis.