Biosynthesis of beta nerve growth factor in mouse submaxillary glands

The biosynthesis of beta nerve growth factor (betaNGF) was studied in isolated mouse submaxillary glands incubated with L-[35S]cystine. Sodium dodecyl sulfate gels of anti-betaNGF immunoprecipitates from labeled gland homogenates showed a single major peak of radioactivity, which comigrated with purified betaNGF. This species was nearly completely precipitated by the addition of equivalent amounts of anti-betaNGF, but was absent from immunoprecipitates obtained by the addition of ferritin plus anti-ferritin. The cystine-containing tryptic peptides of the labeled species appeared identical with those of purified betaNGF. In submaxillary glands from adult male mice, labeling of betaNGF represented approximately 0.2% of the trichloroacetic acid-precipitable radioactivity. Castration reduced this value to one-third, while testosterone treatment of castrated animals restored the relative betaNGF synthesis to normal or more. No betaNGF synthesis could be detected in glands from female animals. Several tissues were examined for their ability to synthesize betaNGF in culture. Only submaxillary gland incorporated detectable amounts of radioactivity into betaNGF. Labeling of betaNGF could also be obtained by direct injection of isotope into the submaxillary gland in vivo. The results are discussed in terms of the integration of betaNGF synthesis into neuronal development and maintenance.     

Tonin, an esteroprotease from rat submaxillary glands

Tonin is an enzyme found in the rat submaxillary glands which liberates angiotensin II from angiotensinogen, the Skeggs tetradecapeptide renin substrate, and angiotensin I. Tonin hydrolyzes benzoyl-arginine ethyl ester, benzoyl-arginine methyl ester, tosyl-arginine methyl ester, benzoyl-arginine p-nitroanilide and other small synthetic substrates at an optimum ph of 9.0. Tonin shows, however, a great specificity with respect to angiotensin I. Tonin is inhibited by diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride at high concentrations (greater than 10(-2) M) and by soybean trypsin inhibitor and aprotinin. Tonin is thus an esteroprotease of the class of the serine protease with trypsin- and chymotrypsin-like activity. Tonin belongs to the same family of enzyme as glandular kallikrein and the gamma subunit of the nerve growth factor.     

Regulation of nerve growth factor synthesis in mouse submaxillary glands by testosterone.

—It has long been known that the activity of nerve growth factor (NGF) in extracts obtained from the male mouse submaxillary gland is higher than in extracts from the female gland, and that the activity present in female glands can be increased by testosterone treatment. This communication presents a study of the mechanism of the testosterone effect. Of several different steroids administered to female Swiss–Webster mice only testosterone propionate led to increased gland NGF activity. The increase did not appear to be due to an enhancement of the activity of pre-existing molecules on sympathetic nerve fiber outgrowth, or due to an altered affinity for the specific antibodies used in the estimation of NGF content, but appeared rather to be due to an accumulation of NFG molecules. The kinetics of change in the male gland NGF content upon castration and secondary testosterone propionate stimulation was analyzed by application of the plateau principle. The rate of loss of NGF from this organ was not measureably different between the castrate and testosterone propionate stimulated state. On the other hand, there was estimated to be a 10-fold difference in the rate of input between the basal and steroid stimulated state. Tracer amounts of radioiodine labelled NGF administered i.v. was not accumulated by the gland, and there is no evidence for uptake of this protein from the circulation. We, therefore, infer that the increased NGF concentration in male submaxillary glands is due to a 10-fold increase in the rate constant of synthesis.     

Tolerance to heat of rats treated by beta-blocker. Role of submaxillary salivary glands

Effect of beta-adrenoceptor blockade on the changes in rectal temperature (RT), heat production (HP) and noradrenaline (NA) concentration in the submaxillary salivary glands (SMSG) of rats exposed to heat (45 degrees C) was studied. Propranolol (P) (15 mg/kg i.p.) decreased the tolerance to heat. The survival time of propranolol-treated (PT) rats was 30 min shorter. The temperature curve of control rats exposed to heat can be divided into three phases: a rapid rise in RT; a plateau (TP) and a prelethal increase. In PT animals, under identical conditions, TP disappears and RT further rises accelerating death. In the initial phase of heat exposure, HP was markedly decreased to the same extent in both experimental groups; but after 20 min HP increases in PT rats. The content of NA from SMSG both in the initial phase and in the TP phase is modified in PT rats.     

Quantitative histoenzymologic characteristics of the submaxillary salivary glands of white rats during an ovarian cycle]

Ovarian cycle in albino rats was applied to ascertain the problem of the relationship between the salivary and endocrine glands, and also of the extent of participation of individual components of the salivary glands with different functional orientation in the endocrine regulation of individual components of the salivary glands. The content of protein, mucopolysaccharides, DNA, and RNA, the activity of NAD- and NADP-diaphorase, alkaline phosphatase, malate and isocitrate dehydrogenase, alpha-leucine-aminopeptidase was studied. Cytospectrophotometric analysis showed that synchronous changes in the activity of the enzymes under study occurred in all the portions of the salivary glands, depending on the ovarian cycle phases. Of the four successive phases of the cycle the greatest activity of the enzymes and of the protein and mucopolysaccharide content was noted during the proestrus and metaestrus. Different metabolic processes were observed in the salivary ducts in comparison with other parts of the gland; this was apparently connected with peculiarities of the secretion and hormone production.     

Purification and characterization of a kallikrein from human submaxillary glands

A tissue kallikrein was purified over 1500-fold from the postmicrosomal supernatant of human submaxillary glands. The purified enzyme gave a single band, corresponding to an apparent molecular weight of 42,000 on SDS-polyacrylamide gel electrophoresis. This enzyme cross-reacted with the anti-human urinary kallikrein antiserum. The purified enzyme was characterized in comparison with the purest human urinary kallikrein preparation. Both enzymes hydrolyzed the synthetic substrate, Ac-Phe-Arg-OMe, most effectively. Aprotinin, TLCK, and PMSF suppressed the enzyme activities, while SBTI, LBTI, and alpha 1-antitrypsin had no effect at all. The purified enzyme generated kinin from the natural substrate, kininogen. It was concluded therefore that the purified enzyme is a typical tissue kallikrein.     

Long-term heat adaptation results in an enhanced efficiency of muscarinically-induced water secretion in rat submaxillary glands

1. Carbamylcholine-induced 86Rb+ and 36Cl- efflux, as markers of calcium mobilization and water secretion, respectively, were studied during 30 days of heat acclimation (at 34 degrees C) in rat submaxillary gland slices using perifusion techniques. 2. The fractional rate of 36Cl- efflux was markedly elevated with acclimation, reaching its maximal level on day 30, while that of 86Rb+, after an initial rise, returned to non-acclimated control levels. The total carbamylcholine-induced efflux of both ions markedly increased throughout the 30 days' acclimation. 3. The rapid increase in ion fluxes was accompanied by a transient increase in Na+ concentrations in the gland and a decrease in the saliva. 4. The data suggest that the acclimation-induced increase in secretory capacity is bi-phasic: initially, a rapid transient rise in ion fluxes accompanies a transient rise in muscarinic receptor density (Kloog et al., 1985). 5. Long term acclimation is characterized by increased efficiency of the cellular secretory mechanism(s), as demonstrated by the chronically increased efflux of ions.