Virus-induced corticosterone in hypophysectomized mice: a possible lymphoid adrenal axis

Infection of hypophysectomized mice with Newcastle disease virus caused a time-dependent increase in corticosterone and interferon production. Prior treatment with dexamethasone completely inhibited the virus-induced elevation in corticosterone concentration, but did not significantly alter the interferon response. Lymphocytes appear to be the most likely source of an adrenocorticotropin-like substance that is responsible for the increased corticosterone, since spleen cells from the virus-infected, but not from control or dexamethasone-treated, hypophysectomized mice showed positive immunofluorescence with antibody to adrenocorticotropin-(1-13 amide). Thus the adrenocorticotropin-like material and interferon appear to be coordinately induced the differentially controlled products of different genes. These findings strongly suggest the existence of a lymphoid-adrenal axis.     

Isolated adrenal cortex cells: hypersensitivity to adrenocorticotropic hormone after hypophysectomy

Cells from the adrenals of hypophysectomized rats (up to 28 days after operation) require less adrenocorticotropic hormone to induce one-half maximal rate of production of 3',5'-adenosine monophosphate than do cells from the adrenals of intact rats. A corresponding increase in sensitivity is reflected in the steroidogenic response to adrenocorticotropic hormone up to 2 days after hypophysectomy.     

Thyrotropin-releasing hormone precursor: characterization in rat brain

To characterize the precursor of mammalian thyrotropin-releasing hormone (TRH), a rat hypothalamic lambda gt11 library was screened with an antiserum directed against a synthetic peptide representing a portion of the rat TRH prohormone. The nucleotide sequence of the immunopositive complementary DNA encoded a protein with a molecular weight of 29,247. This protein contained five copies of the sequence Gln-His-Pro-Gly flanked by paired basic amino acids and could therefore generate five TRH molecules. In addition, potential cleavage sites in the TRH precursor could produce other non-TRH peptides, which may be secreted. In situ hybridization to rat brain sections demonstrated that the pre-proTRH complementary DNA detected neurons concentrated in the parvocellular division of the paraventricular nucleus, the same location as cells detected by immunohistochemistry. These findings indicate that mammalian TRH arises by posttranslational processing of a larger precursor protein. The ability of the TRH prohormone to generate multiple copies of the bioactive peptide may be an important mechanism in the amplification of hormone production.     

Thyrotropin-releasing hormone: regional distribution in rat brain

A sensitive and specific radioimmnunoassay has been used to measure the distribution of thyrotropin-releasing hormone (TRH) in rat brain. All areas of brain tested, except cerebellum, contained readily measurable amounts of TRH. The hypothalamus contained only 31.2 percent of the total brain content of TRH. These results support recent suggestions of central actions for TRH in addition to its hypophysiotropic functions.     

Brassinosteroid signaling: a paradigm for steroid hormone signaling from the cell surface

Plants use the coordinated action of several small-molecule hormones to grow and develop optimally in response to a changing environment. Among these hormones are the brassinosteroids (BRs), the polyhydroxylated steroid hormones of plants. BRs bind a small family of leucine-rich repeat receptor kinases at the cell surface, thereby initiating an intracellular signal transduction cascade that results in the altered expression of hundreds of genes.     

Fetal brain growth: selective action by growth hormone

Growth hormone was administered to pregnant rats maintained under dietary control, and fetal and placental growth and nutrition were examined. Growth hormone had a selective action on brain growth that could not be attributed to nutrient mobilization but suggested a trophic factor which is unique to the brain.     

Rat brain: effects of environmental enrichment on wet and dry weights

Wet weight of rat cerebral cortex was increased by exposure to an enriched environment, as compared with standard colony or impoverished conditions. Dry weights and wet weights were compared and both yielded identical percentage differences between brains of animals experiencing enrichment and those experiencing impoverishment.     

Isolated adrenal cells: adrenocorticotropic hormone, calcium, steroidogenesis, and cyclic adenosine monophosphate

Corticosterone production by isolated adrenal cells in response to adrenocorticotropic hormone is reduced when the cells are incubated in a medium that contains no calcium. This reduction is associated with an equal reduction of accumulation of cyclic adenosine monophosphate. Production of corticosterone and accumulation of cyclic adenosine monophosphate are increased when the calcium concentration in the medium is increased (from zero to 7.65 millimolar). This is in contrast to the situation in "subcellular membrane fragments" of adrenal tissue where high calcium in the medium (> 1.0 millimolar) inhibits cyclic adenosine monophosphate accumulation. We propose that adenyl cyclase in the intact plasma membrane is located in a compartment wherein calcium concentration is low and remains unaffected by the concentration of calcium in the extracellular space. It is proposed that, as the concentration of calcium in the incubation medium is increased from zero to 7.65 millimolar, the strength of the signal generated by the interaction of adrenocorticotropic hormone with its receptor and transmitted to the adenyl cyclase compartment is proportionately increased.     

Calcium as a mediator of adrenocorticotrophic hormone action on adrenal protein synthesis

Calcium stimulates leucine incorporation into protein during incubations of sections and cell-free preparations of the rat adrenal. Like adrenocorticotrophic hormone (ACTH) action, calcium enhances the transfer of amino acid from transfer RNA to protein. Stimulation of leucine incorporation by ACTH and cyclic adenosine monophosphate is best observed when sections are incubated in limiting calcium concentrations.     

Thyrotropin-releasing hormone in specific nuclei of rat brain

The regional distribution of thyrotropin-releasing hormone (TRH) in rat brain was studied. The greatest concentration of TRH was found in the median eminence. High concentrations were also found in several hypothalamic nuclei. Outside the hypothalamus, relatively large amounts of TRH were found in the septal and preoptic areas.     

Nerve endings: rapid appearance of labeled protein shown by electron microscope radioautography

Electron microscope radioautographs of nerve ending fractions from mouse cerebrum show that radioactive protein is associated with nerve endings 15 and 90 minutes after intracerebral injection of tritiated leucine and lysine. The results are consistent with synthesis of protein at nerve endings, or with extremely rapid transport of particulate protein to nerve endings in the mouse cerebrum, or both.     

促黄体素(LH)对猪卵巢颗粒细胞细胞周期及类固醇激素分泌的影响

为揭示促黄体素对猪卵巢颗粒细胞生长及类固醇分泌的影响,从当地屠宰场采集猪卵巢,选择表面直径大于6 mm的卵泡(优势卵泡)作为试验材料,将从其中获得的颗粒细胞进行体外培养,并在培养基中添加不同浓度(0 IU/ml、2 IU/ml和4 IU/ml)的促黄体素(LH),通过流式细胞仪、放射性免疫和定量PCR分别检测细胞周期的...     

Paraoxon: effects on rat brain cholinesterase and on growth hormone and prolactin of pituitary

Cholinesterase activity of brain and content of growth hormone and prolactin in the pituitary were compared after short-term (3 days) and long-term (14 days) treatment with paraoxon in male and female rats. Within 3 days cholinesterase activity was reduced to between 5 and 15 percent of that in controls. The content of growth hormone in the pituitary was increased in long-term experiments by 50 percent. This increase in paraoxon-treated animals-suggests a possible role of a cholinergic mechanism in the regulation of growth hormone secretion.