ABSTRACT
The expression of neural cell surface glycoconjugates during development reflects the precise control of cellular adhesivity that is required for the exact positioning of the developing cells. We have investigated the effect of cell confluency state on the expression of key cell surface glycoconjugates using the mouse neuroblastoma cell line, neuro-2A. There was an up-regulation of expression of the neural cell adhesion molecule (NCAM) coincident with an increase in cell confluency state and a parallel decrease in the expression of the amyloid precursor protein, beta APP. The expression pattern of cell surface glycoconjugates in neuro-2A cells is therefore similar to that observed during the early embryonic period of development during which cells aggregate to form collectives.
Subject(s)
Cell Adhesion Molecules, Neuronal/biosynthesis , Membrane Glycoproteins/biosynthesis , Neurons/metabolism , Neurons/physiology , Amyloid beta-Protein Precursor/biosynthesis , Amyloid beta-Protein Precursor/immunology , Animals , Brain Neoplasms/physiopathology , Cell Adhesion/physiology , Cell Division/physiology , Enzyme-Linked Immunosorbent Assay , Mice , Neuroblastoma/physiopathology , Tumor Cells, Cultured , Up-Regulation/physiologyABSTRACT
The objective was to determine if continuous administration of gonadotropin-releasing hormone (GnRH) or a potent analogue (GnRH-A) for 28 or 56 d would decrease blood concentrations of luteinizing hormone (LH) and testosterone (T) in 5-month old bull calves. Treatments (5 calves/treatment), using a completely randomized design, were: control (vehicle), 3.3, 10 and 30 micrograms GnRH, and 3.3 and 10 micrograms GnRH-A (Leuprolide) per kg bodyweight/d for 28 d, administered via subcutaneously implanted mini-osmotic pumps. A second pump was implanted on day 28 in controls and bulls receiving 10 micrograms GnRH-A until day 56. Blood samples were taken every second day for plasma LH and T concentrations, and every 15 min for 6 hr on days 1, 14 and 27 (and days 40 and 55 where applicable) for plasma LH concentrations. There was an increase (P < 0.05) in basal plasma LH in response to GnRH and GnRH-A on day 1 (1.6, 2.1, 2.1, 2.5, 2.1 and 1.9 ng/ml for control, 3.3, 10 and 30 micrograms GnRH, and 3.3 and 10 micrograms GnRH-A, respectively; pooled s.e.d. = 0.2), but not on days 14 or 27. The number of LH pulses/6 hr was similar on day 1 for GnRH-treated and control calves, but there was a linear decrease (P < 0.05) in pulse frequency in response to GnRH doses on days 14 (1.8, 1.2, 0.6 and 0.0 for control, 3.3, 10 and 30 micrograms GnRH; s.e.d. = 0.5) and 27 (1.8, 1.0, 0.0 and 0.0; s.e.d. = 0.3). On days 1, 14 and 27, both GnRH-A doses suppressed (P < 0.05) LH pulsatility. GnRH (days 1-14) and GnRH-A (days 1-27) increased (P < 0.05) plasma T in a dose-dependent manner. Mean T was greater (P < 0.05) in 10 micrograms GnRH-A-treated than in control calves during days 29-41 (4.6 and 1.8 ng/ml; s.e.d. = 0.6) and days 43-55 (4.1 and 1.8 ng/ml; s.e.d. = 0.4). In conclusion, continuous administration of GnRH or GnRH-A to 5-month old bulls for 28 or 56 d chronically decreased LH pulse frequency, had no effect on basal LH, but increased testosterone concentrations.
Subject(s)
Cattle/metabolism , Gonadotropin-Releasing Hormone/pharmacology , Leuprolide/pharmacology , Luteinizing Hormone/blood , Testosterone/blood , Analysis of Variance , Animals , Dose-Response Relationship, Drug , Gonadotropin-Releasing Hormone/administration & dosage , Hypothalamus/drug effects , Hypothalamus/metabolism , Infusions, Parenteral/veterinary , Leuprolide/administration & dosage , Male , Organ Size , Random Allocation , Testis/anatomy & histology , Testis/drug effects , Testis/metabolism , Time FactorsABSTRACT
Two adjuvants, Freund's complete adjuvant (FCA) and GNE (proprietary product; Intervet Ltd, The Netherlands), were used to immunize cyclic Finnish Landrace ewes (4-6/treatment) against a prostaglandin F-2 alpha-human serum albumin (PGF-HSA) conjugate. Ewes were randomized to the following treatments: (a) control-untreated, (b) control-5 mg HSA in FCA (control-HSA), (c) 5 mg PGF-HSA in FCA (FCA-5 mg), (d) 15 mg PGF-HSA in FCA (FCA-15 mg), (e) 5 mg PGF-HSA in GNE (GNE-5 mg) and (f) 15 mg PGF-HSA in GNE (GNE-15 mg). Ewes were monitored for oestrus (twice daily) and ovarian activity (progesterone concentrations in blood samples taken twice weekly) for 2 consecutive breeding seasons. In the first breeding season, the mean number of oestrous periods detected was 6.0, 5.7, 0.0, 0.2, 1.8 and 0.5 in control, control-HSA, FCA-5 mg, FCA-15 mg, GNE-5 mg and GNE-15 mg-assigned ewes, respectively [pooled standard error of difference (s.e.d.) = 1.2]. A persistent CL formed, on average, 10.0, 10.0, 29.8 and 32.5 days after primary immunization (pooled s.e.d. = 14.6) in 6/6 FCA-5 mg, 6/6 FCA-15 mg, 5/6 GNE-5 mg and 4/4 GNE-15 mg-assigned ewes, respectively; these CL were maintained for, on average, 138.7, 139.0, 127.8 and 129.0 days, respectively (pooled s.e.d. = 15.9).(ABSTRACT TRUNCATED AT 250 WORDS)
