Dexamethasone fails to suppress beta-endorphin plasma concentrations in humans and rhesus monkeys

In humans and rhesus monkeys, dexamethasone decreased concentrations of plasma cortisol but did not alter circulating beta-endorphin immunoreactivity. Contrary to current theory suggesting that pituitary beta-endorphin and adrenocorticotropic hormone are controlled by identical regulatory mechanisms for synthesis and release, our evidence suggests that in higher primates the established glucocorticoid feedback mechanism for the adrenocorticotropic hormone-cortisol system does not regulate beta-endorphin secretion in the same way.     

Identification of pro-opiomelanocortin-derived peptides in the human adrenal medulla

Extracts from adult human adrenals contained high concentrations of immunoreactive beta-endorphin and alpha-melanotropin. Lower quantities of immunoreactive adrenocorticotropic hormone could also be detected. Distribution studies showed the presence of pro-opiomelanocortin fragments in the adrenal medulla. No alpha-melanotropin, beta-endorphin, or adrenocorticotropic hormone could be found in adrenal extracts from several other mammalian species. Analysis of the beta-endorphin-like immunoreactivity using region specific radioimmunoassays interfacing with gel filtration and reverse-phase high-performance liquid chromatography showed the majority of the beta-endorphin-like material to exist as nonacetylated beta-endorphin-(1-31) with a small percentage of lipotropin-sized molecules. The alpha-melanotropin-like immunoreactivity cochromatographed on gel filtration and reverse-phase high-performance liquid chromatography with desacetyl alpha-melanotropin. The data suggest that pro-opiomelanocortin is expressed in the adrenal medulla of humans but is not detectable in the adrenal glands of many other mammalian species.     

Corticotropin-releasing factor stimulates secretion of melanocyte-stimulating hormone from the rat pituitary

Administration of synthetic ovine corticotropin-releasing factor led to rapid, parallel increases in adrenocorticotropin and alpha-melanocyte-stimulating hormone concentrations in rat plasma. Prior treatment with dexamethasone almost completely blocked the adrenocorticotropin response but not the increase in melanocyte-stimulating hormone. These data demonstrate that corticotropin-releasing factor is a potent stimulator not only of adrenocorticotropin secretion from the corticotrophs of the anterior pituitary gland but also of peptide secretion from the intermediate lobe. Such data suggest that melanocyte-stimulating hormone and beta-endorphin play a role in the physiological response to stress.     

beta-Endorphin: possible involvement in the antihypertensive effect of central alpha-receptor activation

Clonidine and L-alpha-methylnoradrenaline (but not D-alpha-methylnoradrenaline) increase the release of a substance with beta-endorphin immunoreactivity from slices of brainstem of spontaneously hypertensive rats, but not that of normotensive rats. It was reported earlier that opiate antagonists inhibit the hypotensive action of clonidine and alpha-methyldopa in spontaneously hypertensive but not in normotensive rats and that beta-endorphin has hypotensive effects of its own. Together, these findings indicate that release of beta-endorphin by central alpha-receptor agonists may contribute to the antihypertensive action of these drugs.     

Ectopic pro-opiolipomelanocortin: sequence of cDNA coding for beta-melanocyte-stimulating hormone and beta-endorphin

A recombinant bacterial plasmid, pMS1, was constructed that contains 318 nucleotides complementary to a portion of pro-opiolipomelanocortin (proOLMC) messenger RNA from an ectopic adrenocorticotropin-producing tumor. The cloned complementary DNA insert, which contains the sequence that codes for all of the beta-melanocyte-stimulating hormone and beta-endorphin portions of proOLMC, as well as the 3' nontranslated section, is identical to the genomic sequence. Hybridization of tumor proOLMC complementary DNA to RNA subjected to electrophoresis and transferred to a nitrocellulose filter revealed two proOLMC messenger RNA species in the tumor polyadenylated RNA, but only one in pituitary polyadenylated RNA. At least one of the tumor proOLMC messenger RNA's is similar, if not identical, to human pituitary proOLMC messenger RNA.     

Antibodies to cerebroside sulfate inhibit the effects of morphine and beta-endorphin

Morphine and beta-endorphin inhibit the shaking response of pentobarbital-anesthetized rats to ice water. Stereotaxically guided administration of antibodies to cerebroside sulfate into the periaqueductal gray region, the most sensitive brain region in which to demonstrate inhibition of this response, antagonizes the effect of morphine and beta-endorphin. These results suggest that cerebroside sulfate may be an integral component of an opiate receptor in rat brain.     

Release of luteinizing hormone in male mice during exposure to females: habituation of the response

Male mice release luteinizing hormone when exposed for a short time to a female. In this experiment, multiple blood samples were withdrawn by atrial cannulas from tethered males during either continuous or intermittent exposure to nonreceptive females. After an immediate, transient release of luteinizing hormone, continuous exposure to the same female was accompanied by only random, spontaneous elevations in plasma levels of this hormone. Successive presentations of the same female at 2-hour intervals elicited gradually diminishing luteinizing hormone responses. Exposing such unresponsive males to novel, diestrous females, however, dramatically stimulated their release of the hormone. These results demonstrate habituation of a socially induced, neuroendocrine response involving reproductive hormones.     

Endotoxin-stimulated opioid peptide secretion: two secretory pools and feedback control in vivo

Small doses of endotoxin evoked a dramatic biphasic response of opioid peptide secretion into blood in sheep. The first phase began within minutes and coincided with a brief hypertensive response to endotoxin well before the appearance of fever or hypotension. The ratio of beta-endorphin to beta-lipotropin fell abruptly at the onset of the second phase of release, suggesting early depletion of a pool rich in beta-endorphin and subsequent emergence of a pool rich in unprocessed precursor. The concentration of cerebrospinal fluid opioids increased tenfold during the second phase. Naloxone administration augmented endotoxin-induced opioid secretion in both early and late phases, suggesting a short-loop feedback regulation of stress-induced endorphin secretion.     

The thymus-adrenal connection: thymosin has corticotropin-releasing activity in primates

Endotoxin-free thymosin fraction 5 elevated corticotropin, beta-endorphin, and cortisol in a dose- and time-dependent fashion when administered intravenously to prepubertal cynomolgus monkeys. Two synthetic component peptides of thymosin fraction 5 had no acute effects on pituitary function, suggesting that some other peptides in thymosin fraction 5 were responsible for its corticotropin-releasing activity. In agreement with these observations, total thymectomy of juvenile macaques was associated with decreases in plasma cortisol, corticotropin, and beta-endorphin. These findings indicate that the prepubertal primate thymus contains corticotropin-releasing activity that may contribute to a physiological immunoregulatory circuit between the developing immunological and pituitary-adrenal systems.     

TANNING IN THE ADULT FLY: A NEW FUNCTION OF NEUROSECRETION IN THE BRAIN

Tanning in the newly emerged fly is induced by a hormone secreted by neurosecretory cells situated in the pars intercerebralis of the brain. The same hormone is contained in the compound ganglion of the thorax, in concentrations six times as high as in the brain. This hormone is believed to act directly on the eflector organ, and not through the secretion of ecdyson or a corpus allatum hormone; its release is effected through nervous impulses reaching the brain by way of the ventral nervous system a few minutes after the fly has emerged from the puparium. The hormone appears to be different from both the prothoraco-tropic and the gonadotropic hormones.     

Excitatory and inhibitory effects of opiates in the rat vas deferens: a dual mechanism of opiate action

Both natural (-)-morphine and its unnatural enantiomer (+)-morphine exert an excitatory action on electrically stimulated contractions of rat vas deferens. Preexposure to (-)-morphine results in cross-tolerance to the inhibitory action of beta-endorphin. (-)-Naloxone and its stereoisomer (+)-naloxone also exert an excitatory action, but only (-)-naloxone bocks the inhibtory action of beta-endorphin. Thus morphine exerts a dual action on a peripheral organ: one an inhibitory action mediated by the stereospecific endorphin receptor that is blocked stereospecifically by naloxone, the other an excitatory action mediated by a nonstereospecific receptor that is not blocked by naloxone. The opiate abstinence syndrome is seen as due to the unmasking of the excitatory action of opiates when its concomitant inhibitory influence is removed by selective blockade by naloxone or weakened by selective tolerance. The view that the rat vas deferens is devoid of morphine receptors is now seen as arising from a reverse example of morphine's dual action: the masking of the inhibitory action of morphine by its concomitant and more potent excitatory action.     

A parathyroid hormone inhibitor in vivo: design and biological evaluation of a hormone analog

A synthetic analog of bovine parathyroid hormone (bPTH), [tyrosine-34] bPTH-(7-34)NH2, was found to inhibit parathyroid hormone action in vivo. When the analog and parathyroid hormone were infused simultaneously to rats at a molar ratio of 200 to 1, the analog inhibited the excretion of urinary phosphate and adenosine 3',5'-monophosphate. When infused alone at the same dose rate, the analog was devoid of agonist activity. The compound was prepared by following design principles developed for inhibitors of parathyroid hormone, and is believed to be the first antagonist of parathyroid hormone that is effective in vivo.     

Amphibian pituitary growth hormone and prolactin: immunochemical relatedness to rat growth hormone

Growth hormone and prolactin were electrophoretically isolated from amphibian pituitaries and then were tested in a radioimmunoassay with labeled rat growth hormone and antiserum to the same hormone. This isolation and purification of the hormones increased the steepness of the slopes of competitive inhibition in this system when compared to those of crude extracts. Both hormones from most species tested showed high immunochemical cross-reactivity, indicating that amphibian growth hormone and prolactin are structurally related to rat growth hormone.     

Fasting associated with decrease in hypothalamic beta-endorphin

In rats that were fasted for 2 to 3 days there was a decline in hypothalamic, but not pituitary, beta-endorphin. There was no change in pituitary or hypothalamic adrenocorticotropin content as a result of fasting. Endogenous opiates may be involved in physiological adaptation to fasting.     

医用激素与植物生长调节剂对杜仲皮增厚效应的比较研究

用浓度500 mg/L的人体医用激素和几种植物生长调节剂对6龄杜仲树皮增厚作用进行比较表明,经过一个年生长周期,医用激素使杜仲皮厚度从1.2 mm增加到3.5 mm,是对照部位皮厚度的2.2倍,比ABT1＃多增厚20,比NAA多增厚37.在树皮增厚的同时,树干木质也明显增粗.     

Gonadotropin secretion during sleep in normal adult men

Release of luteinizing hormone and follicle stimulating hormone during sleep in young adult men occurred in unrelated, random, arrhythmic peaks, with no consistency from night to night in the same subject. Release of luteinizing hormone was modestly but significantly larger (14 perecnt) during rapid-eye-movement sleep than it was in non-REM sleep, but release of follicle stimulating hormone was not clearly related to stages of sleep.     

The twitch in horses: a variant of acupuncture

The twitch procedure in horses attenuates the increase in the heart rate evoked by pain-inducing stimuli and the reaction of the animals to such stimuli. Endorphin systems are probably involved in the effectiveness of the twitch, since its action is blocked by naloxone and its application increases plasma concentrations of immunoreactive beta-endorphin. The mode of action of the twitch cannot be explained by the generally accepted theory of divertive pain and may resemble that of classical acupuncture.     

Multiple circadian oscillators regulate the timing of behavioral and endocrine rhythms in female golden hamsters

A single daily "surge" in pituitary luteinizing hormone release was observed in ovariectomized-estrogen-treated hamsters expressing an intact circadian rhythm of locomotor activity. In contrast, two luteinizing hormone surges occurred within a single 24-hour period in hamsters whose activity rhythm had dissociated or "split" into two distinct components. These observations indicate that both behavioral and endocrine circadian rhythms are regulated by the same multioscillator system, which seems to be composed of at least two distinct circadian oscillators.     

All members of the MHC multigene family respond to thyroid hormone in a highly tissue-specific manner

In mammals different isoforms of myosin heavy chain are encoded by the members of a multigene family. The expression of each gene of this family is regulated in a tissue- and developmental stage-specific manner as well as by hormonal and various pathological stimuli. In this study the molecular basis of isoform switches induced in myosin heavy chain by thyroid hormone was investigated. The expression of the myosin heavy chain gene family was analyzed in seven different muscles of adult rats subjected to hypo- or hyperthyroidism with complementary DNA probes specific for six different myosin heavy chain genes. The results demonstrate that all six genes are responsive to thyroid hormone. More interestingly, the same myosin heavy chain gene can be regulated by thyroid hormone in highly different modes, even in opposite directions, depending on the tissue in which it is expressed. Furthermore, the skeletal embryonic and neonatal myosin heavy chain genes, so far considered specific to these two developmental stages, can be reinduced by hypothyroidism in specific adult muscles.     

Establishment of four functional, clonal strains of animal cells in culture

The single-cell plating technique was used to develop four clonal cell lines that perform organ-specific functions after being serially cultured for prolonged periods. These strains include steroid-secreting Leydig cells, melanomacells that form pigment, and two strains from a hormone-secreting rat pituitary tumor. One of the cell lines from the pituitary tumor secretes growt hormone, while another line derived from the same tumor secretes a substance similar to adrenocorticotropic hormone.