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Biomedical subjects

C H Li

Publications and source records attributed to C H Li.

At least 271 records · Page 15Linked to original sources
PubMed1981

Effects of beta-lipotropin and beta-lipotropin-derived peptides on aldosterone production in the rat adrenal gland.

To investigate the role of non-ACTH pituitary peptides on steroidogenesis, we studied the effects of synthetic beta-lipotropin, beta-melanotropin, and beta-endorphin on aldosterone and corticosterone stimulation using rat adrenal collagenase-dispersed capsular and decapsular cells. beta-lipotropin induced a significant aldosterone stimulation in a dose-dependent fashion (10 nM-1 muM). beta-endorphin, which is the carboxyterminal fragment of beta-lipotropin, did not stimulate aldosterone production at the doses used (3 nM-6 muM). beta-melanotropin, which is the middle fragment of beta-lipotropin, showed comparable effects on aldosterone stimulation. beta-lipotropin and beta-melanotropin did not affect corticosterone production in decapsular cells. Although ACTH(1-24) caused a significant increase in cyclic AMP production in capsular cells in a dose-dependent fashion (1 nM-1 muM), beta-lipotropin and beta-melanotropin did not induce an increase in cyclic AMP production at the doses used (1 nM-1 muM). The beta-melanotropin analogue (glycine[Gly](10)-beta-melanotropin) inhibited aldosterone production induced by beta-lipotropin or beta-melanotropin, but did not inhibit aldosterone production induced by ACTH(1-24) or angiotensin II. Corticotropin-inhibiting peptide (ACTH(7-38)) inhibited not only ACTH(1-24) action but also beta-lipotropin or beta-melanotropin action; however it did not affect angiotensin II-induced aldosterone production. (saralasin [Sar](1); alanine [Ala](8))-Angiotensin II inhibited the actions of beta-lipotropin and beta-melanotropin as well as angiotensin II. These results indicate that (a) beta-lipotropin and beta-melanotropin cause a significant stimulation of aldosterone production in capsular cells, (b) beta-lipotropin and beta-melanotropin have a preferential effect on zona glomerulosa cells, (c) beta-melanotropin contains the active peptide core necessary for aldosterone stimulation, (d) the effects of these peptides on aldosterone production may be independent of cyclic AMP, and (e) the receptors for beta-lipotropin or beta-melanotropin may be different from those for ACTH or angiotensin II.

Adrenal Glands↗
PubMed1981

Behavioral and biological effects of acute beta-endorphin injection in schizophrenic and depressed patients.

In this double-blind study, beta-endorphin, 4-15 mg, was administered intravenously to 6 schizophrenic and 4 depressed patients. There were neither significant differences in behavioral ratings between beta-endorphin and placebo for the overall group nor for either the schizophrenic or depressed subgroup. Clinical worsening and improvement were observed in individual schizophrenic patients. There was no evidence of late-appearing therapeutic effects in 4 schizophrenic patients rated for 5 consecutive days after placebo and drug infusions. In 1 patient 10 mg of beta-endorphin produced neuroendocrine effects comparable to those produced by 5 mg of intravenously administered methadone; in 2 other patients it produced large increases in circulating opioid activity as determined by radioreceptor assay. These biological data support the notion that parenterally administered beta-endorphin exerts significant opiate-like activity in vivo.

Adult↗
PubMed1981

Effects of exogenous beta h-endorphin on pituitary hormone secretion and its disappearance rate in normal human subjects.

The disappearance rate of the immunoreactive beta h-endorphin and the effects of beta h-endorphin on pituitary hormone secretion were investigated in normal volunteers. Synthetic human beta h-endorphin was administered as a 2.5-mg iv bolus to five normal women resulting in a 1000-fold increase in concentration of circulating immunoreactive beta h-endorphin within 2.5 min. This was followed by a triple exponential disappearance curve yielding an initial fast component with a half-time (t 1/2; +/-SD) of 4.1 (+/-0.6) min, a midrange component with a t 1/2 of 13.1 (+/-0.6 min, and a slow component with t 1/2 of 46.2 (+/-7.0) min. In both male and female subjects this dose of beta-endorphin induced a significant increase in the levels of PRL and a significant decline in the concentration of LH, without altering basal levels of GH and TSH.

Endorphins↗
PubMed1981

Beta-endorphin. Vasodilating effect on the microcirculatory system of hamster cheek pouch.

beta-Endorphin, enkephalins and morphine dilated in vivo the arteriole of the microcirculatory system in hamster cheek pouch. beta-Endorphin had the highest potency and morphine the lowest. The effect was dose dependent and blocked competitively by the opiate antagonist, naloxone. The result demonstrated an effect of the opiates on the arteriole of the cutaneous circulation. This effect probably plays an important role in thermoregulation.

Animals↗
PubMed1981

beta-Endorphin. Circular dichroism of synthetic human analogs with various chain lengths in methanol solutions.

The alpha-helix content of human beta-endorphin (beta h-EP) has been determined by circular dichroism (CD) in solutions ranging from 0 to 95% methanol in water. In addition, the CD spectra of beta h-EP-(1-30),-(1-29),-(1-28),-(1-27),-(1-26),-(1-21) and -(1-15) have been examined in 90% methanol, and their alpha-helix contents estimated using parameters determined for this solvent. Addition of methanol to beta h-EP solutions brings about a noncooperative formation of alpha-helix. An attempt to correlate secondary structure in methanol with biological and immunological activities showed limited direct correspondence, but may indicate the involvement of the tertiary interactions.

Amino Acid Sequence↗
PubMed1980

Beta-lipotropin: a new aldosterone-stimulating factor.

Beta-Lipotropin stimulated the production of aldosterone in collagenase-dispersed rat adrenal capsular cells. The maximum response obtained with beta-lipotropin was the same as the response obtained with corticotropin and was greater than that obtained with angiotensin II. These data suggest that beta-lipotropin may play a role in aldosterone regulation.

Adrenal Glands↗
PubMed1980

Binding of 3H-beta-endorphin to rat brain membranes: characterization of opiate properties and interaction with ACTH.

The binding of tritiated beta-endorphin (3H-beta-EP) to brain homogenates is described. This has been difficult to achieve due to the lack of availability of 3H-beta-EP and to technical difficulties associated with high non-specific binding of beta-EP. We now report that 3H-beta-EP binding is saturable, stereospecific, has high affinity and is inhibited by sodium. Its dissociation rate is ten-fold longer than that of naloxone. Its regional distribution exhibits interesting differences from naloxone and enkephalin binding. ACTH1-24 appears to displace it more effectively than it displaces 3H-naloxone. The results are discussed in terms of multiple transmitter systems and the multiple opiate receptor hypothesis.

Adrenocorticotropic Hormone↗
PubMed1980

beta-Endorphin and schizophrenia.

To study the effects of beta-endorphin in chronic schizophrenia, nine male patients participated in a double-blind crossover comparison of a single intravenous 20-mg injection of beta-endorphin and saline. Bolus injection of beta-endorphin from an albumin-coated syringe produced markedly higher plasma concentrations than did slow intravenous infusion from a non-albumin-coated syringe. Beta-endorphin intravenously injected in nine patients produced a statistically significant increase in serum prolactin levels. In one patient, both 10 mg of morphine sulfate and 20 mg of beta-endorphin produced similar increases in the alpha power of the EEG. In eight patients, beta-endorphin administration was associated with a statistically significant but not clinically obvious improvement in schizophrenic symptoms.

Adult↗
PubMed1980

beta-Endorphin. Intravenous infusion causes behavioral change in psychiatric inpatients.

Ten depressed and eight schizophrenic patients received synthetic human beta-endorphin infusions in a double-blind, placebo-controlled, crossover design. Physicians' and nurses' ratings and patients' self-ratings were used to measure behavioral change. Depressed patients improved significantly two to four hours after beta-endorphin treatment when compared with placebo treatment. There was no significant change in the schizophrenic patients as a group, although six of eight worsened after beta-endorphin treatment. No significant behavioral effects were observed during the infusions themselves or on postinfusion days.

Adolescent↗
PubMed1980

Effects of beta-lipotropin on aldosterone production in rats.

1. beta-Lipotropin has a potent aldosterone stimulating effect in vitro and in vivo in rats. 2. The maximum aldosterone response to beta-lipotropin was the same as to ACTH and greater than to angiotensin II. 3. Although doses of ACTH which maximally stimulated aldosterone significantly increased cyclic AMP production, maximally stimulating doses of sheep beta-lipotropin did not increase cyclic AMP production significantly. 4. These data suggest that beta-lipotropin may play a role in aldosterone regulation through a mechanism different from that of ACTH.

Adrenal Glands↗
PubMed1980

Isolation and characterization of beta-endorphin-like peptides from bovine brains.

Four beta-endorphin-like peptides from bovine brain extracts have been identified by their behavior in CM-cellulose chromatography, gel filtration, high-performance liquid chromatography, and radioimmunoassay. Two of them have been isolated in sufficient quantity for amino acid analysis, radioimmunoassay, and radioreceptor assay. One peptide has an amino acid composition nearly identical to that of beta-endorphin with 56% of the radioimmunoreactivity and 2.3% of the potency in the radioreceptor assay of beta-endorphin. The amino acid content of the other beta-endorphin-like peptide is very different from that of bovine beta-endorphin but it has 47% of the radioimmunoreactivity and 1% of the potency in the radioreceptor assay of beta-endorphin.

Amino Acids↗
PubMed1980

beta-Endorphin: characteristics of binding sites in rabbit spinal cord.

The interaction of human beta-endorphin with binding sites in rabbit spinal cord has been characterized. The stereospecific high-affinity binding sites are concentrated in the dorsal half of the spinal cord. Scatchard analysis of the binding data shows heterogeneity of the binding sites that can be resolved into two populations with apparent dissociation constants of 3.0 (+/-2.0) X 10(-10) and 3.3 (+/- 0.5) X 10(-9) M. Sodium ions decrease the binding of human beta-endorphin to spinal cord to the same extent as found in rat brain. The ability of several opiates and opioid peptides to inhibit the binding of human beta-endorphin is also presented.

Animals↗
PubMed1980

Isolation and amino acid sequence of gamma-lipotropin from human pituitary glands.

gamma-Lipotropin has been purified to homogeneity from human pituitary glands. It consists of 56 amino acids with one residue each of Trp, Thr, Val, Tyr, and Phe. The amino acid sequence has been determined as follows: H-Glu-Leu-Thr-Gly-Gln-Arg-Leu-Arg-Gln-Gly-Asp-Gly-Pro-Asn-Ala-Gly-Ala-Asp-Asp-G ly-Pro-Gly-Ala-Gln-Ala-Asp-Leu-Glu-His-Ser-Leu-Leu-Val-Ala-Ala-Glu-Lys-Lys-Asp- Glu-Gly-Pro-Tyr-Arg-Met-Glu-His-Phe-Arg-Trp-Gly-Ser-Pro-Pro-Lys-Asp-OH. Comparison with the structure of the ovine and porcine hormones reveals that the 23-amino-acid sequence at the COOH terminus is highly conserved in evolution.

Amino Acid Sequence↗
PubMed1980

Beta-Endorphin: dissociation of receptor binding activity from analgesic potency.

Biological activities of synthetic camel beta-endorphin and human beta-endorphin (beta h-EP) have been measured by the radioreceptor binding assay, using [Tyr27-3H]-beta h-EP as the primary ligand and by the tail-flick test for analgesic potency. Four synthetic analogs of beta h-EP, namely [Gly31]-beta h-EP-Gly-NH2, [Gly31]-beta h-EP-Gly-Gly-NH2, [Gln8,Gly31]-beta h-EP-Gly-Gly-NH2, and [CH3(CH2)4NH231]-beta h-EP, have also been assayed by the same procedures. Results indicate a clear dissociation of radioreceptor binding activity from analgesic potency.

Amino Acid Sequence↗