Neuron-astrocyte interactions play a crucial role during development and in the adult brain. During development, glial cells are involved in the guidance of neuronal precursors and in extending neuronal fiber projections. Astrocytes can promote neurite outgrowth, both "in vitro" and "in vivo". In the central nervous system (CNS), they express receptors for a variety of growth factors (GFs), neu...

Hyperstimulation of ovarian function with human FSH (hFSH) attenuates the preovulatory surge of LH. These experiments aimed at investigating the mechanism of ovarian-mediated FSH suppression of the progesterone (P(4)) receptor (PR)-dependent LH surge in the rat. Four-day cycling rats were injected with hFSH, oestradiol benzoate (EB) or vehicle during the dioestrous phase. On pro-oestrus, their ...

Twenty-five cows were divided equally into five groups to determine whether [D-Trp6]luteinizing hormone releasing hormone (LHRH-A) microencapsulated in poly (DL-lactide co-glycolide) would increase basal serum concentrations of LH during the postpartum period. On d 5 postpartum, cows were injected i.m. with 2 ml of vehicle alone (Group 1) or vehicle containing microcapsules calculated to releas...

Our previous studies showed that treatment of female rats with large doses of Cetrorelix, an antagonist of luteinizing hormone-releasing hormone (LHRH), reduces levels of serum LH, estradiol, progesterone, and the concentration of pituitary LHRH receptors (LHRH-Rs) and their mRNA expression. Serum LH and testosterone levels and pituitary LHRH-R in male rats are also decreased by high doses of C...

We report our experimental results supporting the hypothesis that a specific metal-chelating peptide (CP) on the NH2 terminus of a protein can be used to purify that protein using immobilized metal ion affinity chromatography (IMAC). The potential utility of this approach resides with recombinant proteins since the nucleotide sequence that codes for the protein can be extended to include codons...

Hypophysial portal blood and peripheral blood were obtained from conscious, unrestrained rams to measure simultaneously the secretion of LHRH and LH in entire rams and rams which had been castrated for 2-15 days (short-term castration) and for 1-6 months (long-term castration). The apparatus for portal blood collection was surgically implanted using a transnasal trans-sphenoidal approach and, 4...

The specific role of each oestrogen receptor (ER) isoform (alpha and beta ) and site (nucleus and plasma membrane) in LH release was determined in ovariectomized (OVX) rats injected over 6 days (days 15-20 after OVX) with a saturating dose (3 mg/day) of tamoxifen (TX), a selective ER modulator with nuclear ERalpha agonist actions in the absence of oestrogen. This pharmacological effect of TX wa...

The initiation of mammalian puberty requires the activation of hypothalamic neurons secreting the neuropeptide luteinizing hormone-releasing hormone (LHRH). It is thought that this activation is caused by changes in trans-synaptic input to LHRH neurons. More recently, it has been postulated that the pubertal increase in LHRH secretion in female animals also requires neuron-glia signaling mediat...

Nicotine at very low doses (5-30 nM) induced large amounts of luteinizing hormone-releasing hormone (LHRH) release, which was monitored as slow membrane depolarizations in the ganglionic neurons of bullfrog sympathetic ganglia. A nicotinic antagonist, d-tubocurarine chloride, completely and reversibly blocked the nicotine-induced LHRH release, but it did not block the nerve-firing-evoked LHRH r...