Stimulation of rabbit lacrimal gland secretion with biologically active peptides

1988 ◽  
Vol 254 (3) ◽  
pp. G300-G306
Author(s):  
D. A. Dartt ◽  
M. Shulman ◽  
K. L. Gray ◽  
S. R. Rossi ◽  
C. Matkin ◽  
...  

To determine whether biologically active peptides can stimulate lacrimal gland secretion, we measured fluid and protein secretion from the cannulated lacrimal gland excretory duct of anesthetized rabbits after arterial injection of various peptides. Vasoactive intestinal peptide (VIP, 0.003-3 nmol) and porcine histidine isoleucine-containing peptide (PHI, 0.01-3 nmol) stimulated fluid and protein secretion in a dose-dependent manner. Cholecystokinin octapeptide (CCK-8, 0.01-3 nmol) stimulated fluid but not protein secretion. Neither bombesin nor eledoisin in doses as high as 3 nmol stimulated fluid or protein secretion. When combinations of high or low doses of VIP and the cholinergic agonist acetylcholine (ACh) were injected simultaneously, fluid and protein secretion was additive. We concluded that VIP and PHI stimulated secretion of lacrimal gland fluid and protein, CCK-8 stimulated secretion of fluid, and bombesin and eledoisin did not stimulate either fluid or protein secretion. VIP and ACh, both found in lacrimal gland nerve endings, stimulate lacrimal gland fluid and protein secretion by separate pathways.

1989 ◽  
Vol 257 (1) ◽  
pp. G151-G156 ◽  
Author(s):  
M. M. Cripps ◽  
K. Patchen-Moor

The synthetic enkephalin analogue, [D-Ala2]Met-enkephalinamide (DALA) was used to investigate opioid peptide modulation of lacrimal protein secretion. By use of an in vitro perifusion system, the secretion of peroxidase by rat lacrimal gland fragments was measured during continuous stimulation for up to 60 min. DALA had no effect on unstimulated secretion of peroxidase. However, the addition of DALA to the perifusion medium resulted in a dose-dependent (10 nM-10 microM) inhibition of carbachol-stimulated peroxidase release. The maximum effect of DALA was achieved at a dose of 10 microM, which resulted in a 54% inhibition of carbachol-induced secretion. The opiate antagonist naloxone (10 nM-10 microM) did not alter basal or carbachol-stimulated peroxidase release. The effect on 10 microM carbachol-stimulated secretion by the addition of 3 microM DALA, however, was reversed in a dose-dependent manner by naloxone. The extent of inhibition of vasoactive intestinal peptidergic (VIPergic) stimulation (50 nM VIP) by DALA was similar to the inhibition of cholinergic stimulation of peroxidase release by gland fragments. Neither alpha 1-adrenergic stimulation of secretion nor a synergistic stimulation by VIP and carbachol was inhibited by the enkephalin analogue. We conclude that DALA exerts an inhibitory modulation of cholinergic and VIPergic stimulation of in vitro lacrimal protein secretion and suggest a physiological role for methionine enkephalin as an inhibitory peptide involved in the regulation of lacrimal gland function.


1986 ◽  
Vol 109 (1) ◽  
pp. 111-117 ◽  
Author(s):  
F. F. G. Rommerts ◽  
J. W. Hoogerbrugge ◽  
H. J. van der Molen

ABSTRACT After the addition of charcoal-treated testicular fluid to Leydig cells isolated from 22-day-old rats, pregnenolone production could be increased to a maximum of tenfold within 30 min in a dose-dependent manner. Testicular fluid, but not serum, further increased pregnenolone formation threefold when pregnenolone production by Leydig cells was stimulated by the addition of LH-releasing hormone (fourfold), LH (25-fold) and 22R-hydroxycholesterol (300-fold). The effect of testicular fluid on steroid production in the presence of 22R-hydroxycholesterol was not inhibited by cycloheximide whereas cycloheximide completely inhibited the effect of LH. It appears unlikely that steroids, lipoproteins or other plasma components constitute the stimulatory agents in testicular fluid. The biologically active principles may be locally produced factors with a molecular weight > 25 000. Similar biological activities could be shown in testicular lymph from boars but not in systemic lymph from boars nor in charcoal-treated bovine follicular fluid. The presumably locally produced factor(s) may amplify the effect of LH and can thus act as a local modulator(s). J. Endocr. (1986) 109, 111–117


2014 ◽  
Vol 25 (3-4) ◽  
pp. 24-33
Author(s):  
O. I. Dzjuba ◽  
M. V. Yatsenko

The article deals with the history of the study and the current state of research of physiological and biochemical properties of the plant genus Sedum that are useful for human and has been used in folk medicine for many years. It was noticed that antioxidant properties of extracts from plants S. sarmentosum, S. sempervivoides, S. takesimense were caused by the presence of phenolic compounds. Methanol extract of plants S. takesimense exhibited strong scavenging activities against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radicals as well as significant inhibitory effects on lipid peroxidation and low density lipoprotein (LDL) oxidation induced by a metal ion Cu2+. Various immunomodulatory activities of various fractions of plants extracts (S. dendroideum, S. kamtschaticum, S. sarmentosum, S. telephium) are observed. It was shown that the ethanol extract of S. sarmentosum and it’s fractions suppressed specific antibody and cellular responses to ovalbumin in mice. The methanol extract of plants S. sarmentosum reduced the levels of anti-inflammatory markers, such as volume of exudates, number of polymorphonuclear leukocytes, suppressed nitric oxide synthesis in activated macrophages via suppressed induction of inducible nitric oxide synthase (iNOS). Polysaccharides fractions from plants S. telephium inducing productions of tumor necrosis factor alpha (TNF-α), increasing the intensity of phagocytosis in vitro and in vivo. Methanol extract from the whole part of S. kamtschaticum strongly inhibit PGE2 production from lipopolysaccharide-induced RAW 264.7 cells, a mouse macrophage cell line via modulating activity in gene expression of the enzyme cyclooxygenase-2 (COX-2). The methanol extract of plants S. sarmentosum and the major kaempferol glycosides from S. dendroideum have antinociceptive activity. It was noticed that anti-adipogenic activity of extracts from plants S. kamtschaticum were caused by inhibition of peroxisome-proliferator-activated receptor γ (PPARγ) expression and it’s dependent target genes, such as genes encoding adipocyte protein 2 (аР2), lipoprotein lipase (LPL), adiponectin and CD36. Polysaccharides fractions from S. telephium cause inhibition of cell adhesion of human fibroblast (MRC5) to laminin and fibronectin via interfere with integrin-mediated cell behaviour and they contributed to the role of polysaccharides in cell-matrix interaction. The methanol extract of plants S. sarmentosum exhibited a significant inhibitory activity in the chick embryo chorioallantoic membrane angiogenesis in a dose-dependent manner. The crude alkaloid fraction of S. sarmentosum caused a dose-dependent inhibition of cell proliferation on murine hepatoma cell line BNL CL.2 and human hepatoma cell line HepG2 without necrosis or apoptosis. Alkaloids from plants S. sarmentosum may improve survival of hepatoma patients via the inhibition of excessive growth of tumor cells. Plant’s juices have antiviral activity (S. sarmentosum, S. spurium, S. stahlii). Crude ethanol extract S. praealtum have spermicidal activity of the in mice and a relevant inhibitory effect of aqueous extract on human spermatozoa motility as well as an anti-fertilizing activity in rats. Hepatoprotective triterpenes, e.g., δ-amyrone, 3-epi-δ-amyrin, δ-amyrin and sarmentolin were isolated from S. sarmentosum. 2- and 2,6-substituted piperidine alkaloids (e.g., norsedamine, allosedridine, sedamine, allosedamine) are observed in plants S. acre, which in the presence of data on the use of pyridine and piperidine derivatives for treating neurodegenerative diseases (e.g., Alzheimer's disease), points on the promising research in this area. Taking into account that biologically active compounds are accumulated in the aboveground vegetative organs of plants of Sedum, the prospects of further study of the use of Sedum for the purposes of biotechnology and in the pharmaceutical industry becomes apparent. This work extends the existing views regarding the use of plants Sedum.


2010 ◽  
Vol 16 (30) ◽  
pp. 3390-3400 ◽  
Author(s):  
Abba J. Kastin ◽  
Weihong Pan

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