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Biomedical subjects

L L Anderson

Publications and source records attributed to L L Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Relaxin and estrogen synergistically accelerate growth and development in the uterine cervix of prepubertal pigs.

UNLABELLED: This study was designed to determine the development and growth-promoting effects of relaxin with or without estrogen on the uterine cervix of prepubertal gilts. Twenty littermate gilts of similar body weight (33 +/- 3 kg; mean +/- SE) at 80 days of age were randomly assigned to four treatments: Vehicle (CONTROL, 1 ml PBS and 1 ml vegetable oil, n = 5); Relaxin (Relaxin, in PBS, 1 ml, 167 micrograms ml-1, n = 5); Estradiol Benzoate (EB, in vegetable oil, 1 ml, 2 mg ml-1, n = 5); and Relaxin plus EB (Relaxin + EB, at the same doses, n = 5), total six intramuscular injections for all treatments. Twenty four hours after the last injection, hysterectomy was performed, and the uterine tissues were immediately frozen at -80 degrees C. Samples were taken from the middle portions of the cervix and the uterine horns and dried to a constant weight to determine the dry weight and water concentration. Homogenates of uterine horns and cervices were analyzed for concentrations and contents of protein, hydroxyproline (collagen index) and DNA. Relaxin alone had no significant effect on any parameters (i.e., wet weight, Relaxin vs. CONTROL: 36 +/- 5 vs. 28 +/- 3 g uterus-1, dry weight 5.6 +/- 0.6 vs. 4.4 +/- 0.4 g uterus-1). EB alone increased significantly (P < 0.05) wet weight of the uterus (EB vs. CONTROL: 85 +/- 23 vs. 28 +/- 3 g uterus-1), dry weight (EB vs. CONTROL: 14.5 +/- 3 vs. 4.4 +/- 0.4 g uterus-1), and hydroxyproline content (EB vs. CONTROL: 47.2 +/- 13 vs. 12.6 +/- 4 mg cervix-1). In the presence of EB, relaxin treatment increased all measurements compared with CONTROL (i.e., wet weight, Relaxin + EB vs. EB: 136 +/- 34 vs. 28 +/- 3 g uterus-1). Compared with EB, Relaxin + EB significantly (P < 0.05) increased the uterine wet weight (Relaxin + EB vs. EB: 136 +/- 34 vs. 85 +/- 23 g uterus-1), the hydroxyproline content (Relaxin + EB vs. EB: 91 +/- 29 vs. 47 +/- 13 mg cervix-1), and DNA content (Relaxin + EB vs. EB: 8.1 +/- 2 vs. 5.4 +/- 1 mg cervix-1). These results indicate that the growth-promoting effects of relaxin on the uterus and cervix may be, at least partly, estrogen-dependent and that the growth and development of the uterus and cervix can be accelerated by a combination of relaxin and estrogen treatment.

Animals↗
PubMed1997

Continuous infusion of relaxin on periparturient progesterone, oxytocin and relaxin plasma concentrations and time of parturition in beef heifers.

These studies were designed to determine whether continuous i.v. infusion of increasing dosages of porcine relaxin during late pregnancy in beef heifers would influence circulating blood concentrations of relaxin, progesterone and oxytocin, and time of onset of parturition. Beef heifers were bred by artificial insemination and, on Day 277, fitted with indwelling jugular cannulas for hormone infusion and blood sampling from Day 277 to Day 286. Intravenous infusion of purified porcine relaxin (pRLX, 3000 U mg-1) was started in heifers (n = 8) at increasing dosages (200 U h-1 on Days 277 and 278, 300 U h-1 on Days 279 and 280, 500 U h-1 on Day 281, 600 U h-1 on Day 282, and 700 U h-1 on Days 283-286). Phosphate-buffered saline (PBS, 10 ml h-1) was infused during these same times to control animals (n = 6). Relaxin treatment steadily increased the circulating plasma concentration of immunoreactive relaxin to more than 120 ng ml-1 compared with less than 0.5 ng ml-1 in PBS-treated controls. Relaxin infusion in increasing dosages over the treatment time was associated with a significant decrease (P < 0.01) in plasma progesterone concentration compared with the PBS controls. The rate of change in progesterone levels between pRLX and PBS groups differed (P < 0.05) at 300 U h-1, 600 U h-1 and 700 Uh-1 dosage intervals, respectively. Plasma levels of oxytocin at 4 h intervals remained similar (P > 0.05) during the pretreatment period and throughout continuous infusion of pRLX and PBS. Mean concentrations of oxytocin in PBS control heifers peaked at 0.95 pgml-1 during the corresponding infusion of 700 Uh-1 pRLX, which peaked at 0.77 pgml-1. Although continuous i.v. infusion of relaxin resulted in a decrease in circulating blood levels of progesterone, it did not significantly reduce the interval between the beginning of pRLX treatment and parturition compared with the PBS-infused control heifers. These results indicate that continuous i.v. infusion of high levels of porcine relaxin resulted in a decrease in progesterone secretion in late pregnant beef heifers.

Animals↗
PubMed1997

Implant brachytherapy: a novel treatment for recurrent orbital rhabdomyosarcoma.

BACKGROUND: Orbital rhabdomyosarcoma is the most common primary malignancy of the orbit in childhood. Tumor resection and exenteration were the preferred treatment modalities for rhabdomyosarcoma. In the past 20 years, however, combined local radiation and systemic chemotherapy have shown excellent survival results. Tumor recurrence after any of the aforementioned therapies is almost always fatal. We have developed a novel treatment for recurrent disease that has resulted in long-term survival for three patients. METHODS: Three patients with recurrent orbital rhabdomyosarcoma were previously treated with primary radiation and chemotherapy. At the time of recurrence, exenteration and localized brachytherapy were performed. An individually molded poly(methylmethacrylate) (Lucite; E. I. du Pont de Nemours & Co., Wilmington, Del.) device loaded with radioactive iodine seeds delivered localized high-dose radiation, 6000 cGy over 6 days, to the orbit without irradiating the brain. RESULTS: All patients are alive and free of disease with follow-up ranging from 4 years and 4 months to 8 years and 4 months. CONCLUSION: A novel technique of delivering localized radiation to the orbit of three children with recurrent orbital rhabdomyosarcoma appears curative.

Brachytherapy↗
PubMed1997

A system for nonradiographic source localization and real-time planning of intraoperative high dose rate brachytherapy.

We have developed a system for source localization and real-time planning of interstitial volume implants for intraoperative radiation therapy (IORT) using high dose rate remote afterloading techniques. Source localization is realized by using an electromagnetic tracking device, which consists of a transmitter coil, a receiver coil, and a signal processing unit, to generate the coordinates and orientation of the receiver. A drawback of the device is its sensitivity to adjacent metallic objects. Localization accuracy was evaluated in an operating room environment, where the metallic objects closest to the receiver are surgical retractors (that, incidentally, preclude radiographic localization). For achievable separation distances, we found an rms error of 0.7 mm in determining the distance between points 2 cm apart, thereby demonstrating the feasibility of the method. The receiver is mounted on a plastic block from which projects a long stylet and the transmitter is located at about 50 cm from the receiver. The stylet is inserted sequentially into source catheters to obtain the location and orientation data that serve as input to treatment planning software. The planning program optimizes source dwell time to make calculated dose conform to the dose prescribed on an ellipsoidal surface to an extent consistent with a certain level of dose uniformity inside the target volume. A least squares method is used that involves minimizing the objective function by a matrix method (nonnegative least squares). We have demonstrated that dwell time optimization can be performed in a short time and that the approach is adequate for the IORT application.

Brachytherapy↗
PubMed1997

Relaxin-induced expression of Fos in the forebrain of the late pregnant rat.

Relaxin, administered parenterally, has been shown to increase the release of oxytocin (OT) into the circulation and increase the firing rate of OTergic neurons. The objective of the present study was to determine if relaxin administration can result in the expression of a transcription factor, suggesting that it alters transcriptional activity within OTergic neurons at the level of the hypothalamus. Primigravid rats were ovariectomized and a jugular cannula was inserted on day 11 of gestation (g11). Pregnancy was maintained by implanting 17 beta-estradiol and progesterone caplets subcutaneously at the time of ovariectomy. At gl9, rats were challenged with intravenous relaxin or isotonic saline and the brains were removed for study. Immunohistochemistry was performed on coronal brain sections, utilizing Fos as a marker of cellular activation. In the group receiving relaxin, Fos-like immunoreactivity (Fos-IR) was abundant only in the supraoptic (SON) and paraventricular nuclei (PVN) of the hypothalamus as well as in the subfornical organ (SFO). In contrast, Fos-IR in the group given isotonic saline was lacking in these three brain regions. A double label study using antibodies against Fos and OT demonstrated that a majority of the Fos-labeled cells in the hypothalamus were OTergic. Because Fos can act as a transcription factor, we interpret these data to indicate that transcription within OTergic cells is altered following relaxin administration, with abundant Fos-IR being limited to the SON and PVN of the hypothalamus and the SFO during late pregnancy in the rat.

Animals↗
PubMed1997

Pregnancy rates per artificial insemination for cows and heifers inseminated at a synchronized ovulation or synchronized estrus.

Two synchronization protocols were tested for lactating dairy cows and heifers. Nulliparous dairy heifers (13 to 23 mo; n = 155) and primiparous and multiparous dairy cows (60 to 289 d postpartum; n = 310) were assigned randomly to two treatments. Controls received 25 mg of PGF2 alpha and were artificially inseminated according to the a.m.-p.m. rule following detected estrus. All controls that were not detected in estrus were injected with 25 mg of PGF2 alpha at 14-d intervals until artificial insemination (AI) at a detected estrus or until timed AI at 72 to 80 h after a third sequential injection of PGF2 alpha. Treated cows and heifers received a protocol that used GnRH and PGF2 alpha to synchronize ovulation (Ovsynch). Cows and heifers that were treated with Ovsynch were injected i.m. with 100 micrograms of GnRH at a random stage of the estrous cycle. Seven days later, cows and heifers in this group received 25 mg of PGF2 alpha followed by a second injection of 100 micrograms of GnRH 30 to 36 h later. Subsequently, the treated cows and heifers received AI 16 to 20 h after the second injection of GnRH. Pregnancy rates per AI were similar (38.9% vs. 37.8%) for control cows and cows treated with the Ovsynch protocol, respectively. However, pregnancy rate per AI was greater for control heifers (74.4%) than for heifers treated with Ovsynch (35.1%). Evaluation of serum progesterone concentrations at each hormonal injection indicated that the first injection of GnRH synchronized luteal function of lactating dairy cows but not of heifers. In summary, one fixed-time AI at a synchronized ovulation provided similar pregnancy rates per AI as did AI following the a.m-p.m. rule after estrus had been induced by PGF2 alpha in lactating cows, but the fixed-time AI was not effective for heifers because of the lack of synchronization.

Animals↗
PubMed1996

The prepubertal ontogeny of luteinizing hormone releasing hormone-like immunoreactivity in the diencephalon and telencephalon of the male Meishan pig brain.

Luteinizing hormone releasing hormone (LHRH) is a decapeptide that regulates reproductive function and behaviors in mammalian species. Because of the importance of proper reproductive function and efficiency in agricultural species, we have investigated the prepubertal ontogeny of LHRH-like immunoreactivity (IR) in the male Meishan pig. The Meishan is a Chinese breed known for reproductive traits including increased litter size and precocious puberty, but slow growth and obesity. Brains of animals from gestational day (g) 30, 50, 70, 90 and 110 and postnatal day (pn) 1, 10, 20 and 50 (duration of pregnancy averaged 114 days) were processed using a standard immunohistochemical technique utilizing a commercially available rabbit anti-LHRH antibody. LHRH-IR in cell bodies and fibers was detected at g30 entering the brain via the terminal nerve and in the septal region of the basal telencephalon. The number of immunoreactive cells increased at g50 and cells were localized primarily to the septum, organum vasculosum of the lamina terminalis, preoptic area and lateral hypothalamus, whereas immunoreactive fibers were present throughout the septum and hypothalamus and had reached the median eminence. The density and distribution of immunoreactive fibers increased by g70 and g90, but did not change dramatically from g90 to pn50. These results indicate that LHRH may be present in the Meishan brain earlier during development and fibers containing LHRH-IR appear to reach the median eminence earlier than previously reported for the domestic pig. These results suggest a breed difference in the ontogeny of reproductive control systems in the pig. Future studies utilizing direct comparisons between domestic and Chinese breeds will be required to investigate the apparent differences in the ontogeny of LHRH-containing systems in the pig.

Animals↗
PubMed1996

Replication and pathogenicity after intranasal and intracranial inoculation of swine with a recombinant pseudorabies virus containing a deletion at the UL/IR junction.

Pseudorabies virus (PRV) is a neurotropic herpesvirus of swine. Previously, we described construction of a recombinant strain of PRV (LLT beta delta 2) which contains a 3.0-kb deletion spanning the junction of the unique long and internal repeat sequences. Compared to the parental strain, Indiana-Funkhauser, and a virus rescued for the deleted sequences (LLT beta res), LLT beta delta 2 replicated efficiently at the site of inoculation, yet exhibited significantly reduced virulence when inoculated intranasally in pigs. In this report, we investigated the effect of the deletion on PRV replication and virulence after intracranial inoculation of swine, in comparison to replication and virulence after intranasal inoculation, in order to more precisely locate the defect in LLT beta delta 2. Four-day-old pigs were infected intranasally with LLT beta delta 2 or LLT beta res and necropsied at various times postinfection. Compared to LLT beta res-infected pigs, tissue distribution of virus, PRV antigen, and lesions of LLT beta delta 2-infected pigs were comparable in all peripheral tissues examined, including trigeminal ganglia, but were reduced in tissues from the central nervous system (CNS). LLT beta delta 2 was able to replicate in the CNS after intracranial inoculation into the cerebral cortex of 2-day-old piglets and to spread from CNS to peripheral tissues. Neurovirulence of LLT beta delta 2 was somewhat reduced, as demonstrated by delayed onset of neurological signs and death in intracranially inoculated pigs. These results indicate that decreased neurovirulence after intranasal inoculation is not due to inability of LLT beta delta 2 to replicate in CNS tissues. The difference in the amount of antigen detected in CNS tissues after intracranial inoculation compared to intranasal inoculation suggests that one defect in LLT beta delta 2 is reduced ability to spread from peripheral neurons to the CNS after intranasal inoculation.

Animals↗
PubMed1996

The prepubertal ontogeny of galanin-like immunoreactivity in the male Meishan pig brain.

Galanin (GAL) is a neuropeptide found in the mammalian brain and is involved in numerous functions including the control of feeding, growth and reproduction, and therefore may be an important peptide to study in agricultural species. We describe the immunohistochemical localization of GAL throughout prepubertal development in the Meishan pig, a Chinese breed known for its superior reproductive characteristics, but slow growth rate and abundant adipose tissue. Brains of animals from gestational day (g) 30, 50, 70, 90 and 110 and postnatal day (pn) 1, 10, 20 and 50 (duration of pregnancy averaged 114 days) were processed using a standard immunohistochemical technique utilizing a commercially available rabbit anti-porcine GAL antibody. Galanin-like immunoreactivity (GAL-IR) in cell bodies and fibers was evident in the brain at g30, primarily in the hypothalamus. Throughout prenatal development, cell bodies containing GAL-IR generally increased in number and distribution in the brain. During postnatal development, the number of cell bodies displaying GAL-IR decreased, particularly in hypothalamic areas. The distribution of GAL-IR in fibers became more widespread throughout gestational development, showing a pattern by pn1 that continued during later postnatal ages. The intensity of GAL-IR in fibers also increased throughout gestation. Some additional increases in immunoreactivity occurred postnatally, especially in the periventricular hypothalamus. The results of this study indicate that the distribution of GAL-IR in cell bodies and fibers in the Meishan pig brain was similar to that seen in other species, including the rat. These results support the hypothesis that GAL participates in the control of feeding, growth and reproduction in the pig.

Animals↗
PubMed1996

The prepubertal ontogeny of neuropeptide Y-like immunoreactivity in the male Meishan pig brain.

Neuropeptide Y (NPY) is widely distributed in the mammalian brain and is involved in numerous functions including the control of feeding, growth and reproduction. Therefore, NPY may be an important peptide to study in agricultural species. This study describes the immunohistochemical localization of NPY throughout prepubertal development in the Meishan pig, a Chinese breed known for its superior reproductive characteristics. Brains of animals from gestational day (g) 30 through postnatal day (pn) 50 (duration of pregnancy averaged 114 days) were processed using a standard immunohistochemical technique utilizing a commercially available rabbit anti-porcine NPY antibody. Neuropeptide Y-like immunoreactivity (NPY-IR) in cell bodies and fibers is evident in many areas of the brain at g30, including the basal telencephalon, hypothalamus, mesencephalon, pons, and medulla. Throughout prenatal development, cell bodies containing NPY-IR generally increase in number and distribution in the brain. During postnatal development the number of cell bodies displaying NPY-IR decreases. The arcuate nucleus of the hypothalamus, shows a dramatic reduction in the number of immunoreactive cell bodies between pn1 (day of birth) and pn20, just before weaning. The distribution of NPY-IR in fibers becomes more widespread throughout gestational development, showing a pattern by g110 that was characteristic of postnatal ages. The intensity of NPY-IR in fibers also increases throughout gestation. Some additional increases in immunoreactivity occur postnatally, especially in the periventricular hypothalamus and the hippocampus. Other brain areas like the caudate nucleus and putamen show decreases in immunoreactivity postnatally. The distribution of NPY-IR in cell bodies and fibers is similar to that seen in other species, including the rat, and supports the hypothesis that NPY participates in controlling feeding, growth and reproduction in the pig.

Animals↗
PubMed1996

Tattoo pigment mimicking metastatic malignant melanoma.

BACKGROUND: The benefits of elective lymph node dissection (ELND) in the treatment of melanoma remain controversial, however, it may be beneficial in some patients. Tattoo pigment from decorative tattoos may migrate to the regional lymph nodes. In patients who develop malignant melanoma and who have been tattooed, this pigment may clinically mimic metastatic disease. OBJECTIVE: We wish to alert clinicians that pigment from tattoos may migrate to the regional lymph nodes. In the unusual instance of a tattooed patient who develops malignant melanoma, when undergoing ELND, surgeons should rely on histologic confirmation of metastatic disease before altering operative plans. METHODS: ELND for malignant melanoma, in a patient with a history of decorative tattoos that had been removed by dermabrasion, was performed. Black lymph nodes that clinically resembled metastatic disease were identified. Subsequent histologic examination revealed normal lymph node architecture with a heavy collection of black pigment. Mass spectrophotometry showed this pigment to be consistent with tattoo dye. RESULTS: A patient who had undergone dermabrasion for removal of decorative tattoos developed malignant melanoma in the same extremity. Clinically suspicious black lymph nodes were identified during ELND. Histologic examination did not reveal metastatic disease. Additional therapy was not considered intra- or postoperatively even though the clinical suspicion of metastatic disease was high. The patient was not subjected to any unnecessary emotional or physical distress pending histologic confirmation. CONCLUSIONS: Tattoo pigment in the lymph nodes may clinically mimic metastatic melanoma. Histologic confirmation of metastatic disease should always be obtained before additional therapy is considered.

Adult↗
PubMed1996

How many nonmelanoma skin cancers require Mohs micrographic surgery?

BACKGROUND: Cost containment in health care is currently a subject of much debate. The rapid spread of managed care is an attempt to influence practice trends and contain costs. Although seldom directly stated, it is implied that some physicians may perform high-cost procedures when not necessarily indicated, an example being Mohs micrographic surgery (MMS). OBJECTIVE: There are little data in the literature indicating what percentage of skin cancers treated by MMS would be appropriate. For such data to be meaningful, a model would have to exist wherein there is no financial incentive or disincentive for performing the procedure. Military medicine provides this unique environment. METHODS: In a retrospective review, we counted the total number of basal cell carcinomas and squamous cell carcinomas diagnosed at Brooke Army Medical Center (BAMC) over a 5-year period. We then determined the number of MMS cases performed on these cancers. RESULTS: A total of 5193 nonmelanoma skin cancers (NMSC) were diagnosed at BAMC and 1701 of these were treated by MMS. Overall, the percentage of NMSC treated by MMS was 32.7% for the 5-year period. CONCLUSION: This information may serve as a framework for physicians and health delivery systems as they negotiate managed care contracts for the management of skin cancer.

Basal Cell Carcinoma↗
PubMed1996

Analysis of factors affecting the therapeutic gain in high dose rate gynecological implants relative to low dose rate implants.

The radiobiological efficacy of high dose rate (HDR) intracavitary implant relative to that of low dose rate (LDR) implants has been represented quantitatively by the therapeutic factor lamba defined as [EDRtum/ERDorgan]HDR/[ERDtum/ERDorgan]LDR where ERD is the extrapolated response dose. The ERDs for the tumor and a critical organ are calculated using the linear-quadratic model and depend on the values of alpha/beta ratio, the tumor and normal tissue repair time constants (mu 1 and mu 1), number (N) of HDR fractions, the dose per fraction (d), and the fractional tumor and organ dose (ft and fl) relative to the dose at the reference point. We have studied the variation of gamma with d, mu t, mu l, ft, and ft and have derived specific conditions for which lamba can have a value equal to or greater than unity leading to a therapeutic gain in HDR. It is found that lamba is less than unity for commonly used parameter values, specifically when mu t is assumed to be equal to mu l. However, if mu t is greater than mu l, lamba can have a value greater than unity for many possible values of ft and fl.

Biophysical Phenomena↗
PubMed1996

Relaxin in peripheral plasma of boars during development, copulation, after administration of hCG and after castration.

Seventy-two Yorkshire boars were used in five experiments to evaluate the temporal changes in relaxin concentrations in peripheral blood plasma during prepubertal development, copulation, after castration and after treatment with hCG. High concentrations of relaxin (484 +/- 27 pg ml-1) were detected at 11 weeks of age but there was no positive correlation with testicular development. Relaxin concentrations fluctuated in mature boars but the results do not suggest a diurnal rhythm, although there is the possibility of pulsatile secretion. A decrease (P < 0.05) in circulating relaxin was observed before and immediately after copulation. Castration of boars at 90, 115, 160 and 200 days of age did not significantly decrease relaxin concentrations within 48 h. Administration of hCG significantly depressed relaxin secretion at 90 days of age but not at 160 days of age. These studies suggest a non-gonadal source of boar relaxin that is not correlated with testicular growth or testosterone concentrations, is modulated by copulation and by hCG but only at specific stages of development.

Animals↗
PubMed1996

Mediation by the central nervous system is critical to the in vivo activity of the GH secretagogue L-692,585.

To investigate the effect of hypophyseal transection (HST) on GH secretagogue activity of the non-peptidyl GH secretagogue L-692,585 in the conscious pig, male castrated swine were randomly assigned to either a hypophyseal stalk transection group (HST; n = 3) or to a sham-operated control group (SOC; n = 3). Treatments administered were L-692,585 (100 micrograms/kg), human GH-releasing factor(1-29)NH2 (GRF; 20 micrograms/kg) or L-692,585 (100 micrograms/kg) + GRF (20 micrograms/kg) on days -7 to -3 before surgery and days +3 to +8 after surgery. To evaluate the integrity of the pituitary gland, the animals were challenged with corticotropin-releasing hormone (CRH; 150 micrograms) or GnRH (150 ng/kg) both before and after surgery. Blood was collected from -60 to +180 min post treatment and assayed for GH, cortisol and LH. Before surgery, no significant difference (P > 0.05) in peak GH response (ng/ml) was present between the two groups (SOC vs HST) in response to L-692,585 (101 +/- 12 vs 71 +/- 9) or L-692,585 + GRF (171 +/- 21 vs 174 +/- 21). Only two out of three SOC vs three out of three HST pigs responded to GRF (13 +/- 2 vs 25 +/- 3) resulting in a significant difference between groups. Following surgery, significant differences were present in peak GH response (ng/ml) between SOC and HST groups following L-692,585 (79 +/- 6 vs 13.8 +/- 1.0); however, the response to L-692,585 + GRF was similar (115 +/- 8 vs 94 +/- 7). All animals responded to GRF; however, a significant difference was present between groups due to the magnitude of the responses. Whereas the cortisol responses (ng/ml) to L-692,585 in the SOC and HST groups were similar before surgery, a significant difference was present after surgery (44.4 +/- 6.4 vs 14.6 +/- 2.1). No significant difference was noted between the HST and SOC groups in response to CRH or GnRH either before or after surgery. These results indicated that L-692,585 induced an immediate GH response in the intact animal in contrast to GRF where the GH release was variable. L-692,585 also stimulated an immediate increase in cortisol levels. Transection of the hypophyseal stalk dramatically decreased but did not ablate the GH or cortisol response to L-692,585. Co-administration of L-692,585 + GRF induced an immediate GH response of similar magnitude in the intact and HST animal. We conclude that L-692,585 has a direct but limited action at the level of the pituitary and that an intact hypophyseal stalk is required for a maximal GH and cortisol response. L-692,585 acts with GRF at the level of the pituitary to induce a maximal GH response. These findings suggest that L-692,585 stimulates GH secretion by acting in combination with GRF and interrupting the inhibitory tone of somatostatin on the somatotroph.

Animals↗