STUDIES ON SPREADING FACTORS : I. THE IMPORTANCE OF MECHANICAL FACTORS IN HYALURONIDASE ACTION IN SKIN

The spreading response induced by intradermal administration of hyaluronidase is influenced not only by enzyme concentration, but also by the volume and pressure of the injection. These pressure-volume factors influence the rate of spreading and determine the final area of spreading. When a constant volume is injected, the rate of spreading to the area determined by the volume of injection is a function of the enzyme concentration. These and other findings have led to the conclusion that hyaluronidase is an effective spreading agent only when the slow diffusion of enzyme in skin is accelerated by a localized increase of interstitial pressure and volume. These considerations of hyaluronidase action in skin have been utilized to explain the shape of the dosage-response curve of hyaluronidase spreading activity, and the differences in the spreading reactions between crude snake venoms and purified hyaluronidase. The significance of the findings as related to the rôle of hyaluronidase in bacterial invasiveness, and in the assay of S. F. are briefly discussed.

STUDIES ON SPREADING FACTORS : II. THE EFFECT OF SERUM UPON HYALURONIDASE SPREADING ACTIVITY

The reaction between normal serum and hyaluronidase has been studied in vitro and under in vivo conditions in skin. Using in vitro conditions of incubation, serum exhibits antihyaluronidase activity as measured by assay of hyaluronidase spreading activity in skin. This confirms the work of others, who have previously described the serum inhibitory factor using other tests of hyaluronidase activity. When, however, hyaluronidase and setum are allowed to incubate in skin under in vivo conditions, no inhibitory influence of serum upon hyaluronidase spreading activity is evident. This latter finding has been taken to indicate that the environmental conditions in skin are unfavorable for the inhibitory reaction of serum upon hyaluronidase. The disparity between the in vivo and in vitro effectiveness of serum, and the significance of the serum factor as a defense mechanism against invasive processes, have been briefly discussed.

Retro analogs related to oxytocin

[D-alle3]-retro-D-deaminotocinamide (I), retro-L-deaminotocinamide (III) and their respective N-formyl derivatives (II and IV) were synthesized by the stepwise active ester method: deaminotocinamide was prepared by the solid-phase method. The retro-analogs of deaminotocinamide, tested at concentrations up to 10)-5)M, were found to be without activity as agonists or antagonists in the oxytocic assay. At 10(-4)M,[D-alle]-retro-D-deaminotocinamide is a weak competitive inhibitor of oxytocin. [D-alle3, Gly7]-retro-D-deaminooxytocin (V) was synthesized either by the active ester method or by a fragment condensation method employing the retro-D-RING, [D-alle3]-retro-D-deaminotocinamide, and D-tail, Boc-Gly-D-Leu-Gly, as the fragments...

Relationship of dehydroepiandrosterone and cortisol in disease

Does dehydroepiandrosterone act as an adrenal hormone in humans to maintain cortisol homeostasis by serving as a cortisol antagonist? If so, dehydroepiandrosterone might block the development of the diverse pathological processes potentiated by prolonged cortisol hyperactivity. And the plasma concentrations of total dehydroepiandrosterone and total cortisol, expressed as a C/D ratio, would have an important influence on the development of age-related pathology in diseases exacerbated by cortisol hyperactivity. Several major age-related diseases, designated as cortisol-potentiated diseases, belong in this category. The C/D concept predicts, other factors being equal, that the risk of initiation and progression of these diseases at all ages is directly related to the C/D ratio, individuals with elevated C/D ratios being at high risk.

Longitudinal study of adrenal steroids in a cohort of HIV-infected patients with hemophilia

The objective of the study was to relate plasma dehydroepiandrosterone sulfate (DHEA-S) concentrations to the progression of HIV infection in individual HIV-infected men with hemophilia and to obtain information on the cause of DH EA-S alterations. Blood samples were obtained from 16 men with hemophilia; in 9 men serial samples were available for up to 11 years after HIV-1 infection. Control samples were obtained from men of comparable ages without hemophilia or HIV infection. Measurements were made of CD4+ cell counts, plasma adrenocorticotropic hormone (ACTH), cortisol, DHEA, DHEA-S, and prolactin. Before HIV infection, men with hemophilia had significantly lower plasma levels of DHEA-S than control men. After infection, 3 of 9 subjects studied serially had little or no change in plasma DHEA-S levels or in CD4+ cell counts over 11 years. Four of the 9 i n whom AIDS developed had progressive decreases in plasma DHEA-S concentrations that, in some cases, preceded a precipitous fall in CD4+ cell counts. Major decreases in plasma DHEA-S levels before falls in CD4+ counts were observed in 2 ot her subjects who had other severe illnesses. None of the decreases in DHEA-S levels were associated with decreased concentrations of plasma cortisol, ACTH, or prolactin. We conclude that plasma DHEA-S is an indicator of general health rather than a specific indicator for progression of HIV. The decrease in plasma DHEA-S is not related to ACTH stimulation of the adrenal gland or to cortisol secretion, but it may be related to cytokines that can inhibit 17-hydroxylation of DH EA-S precursors.

Comparative effects of dehydroepiandrosterone and related steroids on peroxisome proliferation in rat liver

Dehydroepiandrosterone (DHEA) is known to induce peroxisome proliferation and peroxisomal enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase (PBE) mRNA in the rat liver. We have compared the effects of 6 intermediate metabolites of DHEA on the induction of peroxisome proliferation and PBE mRNA. Administration of epiandrosterone, etiocholanolone, androstenedione, estrone or estradiol for 2 weeks in the diet at 0.45% concentration to adult male F-344 rats failed to induce significant increases in peroxisome proliferation and PBE mRNA when compared to the parent compound DHEA. Dietary administration of 5-androstene-3 beta,17 beta-diol (ADIOL) for 2 weeks at 0.45% concentration caused an increase in PBE mRNA and peroxisome proliferation but to a lesser extent than DHEA. Following a single intragastric dose of DHEA an increase in PBE mRNA level was observed in the liver at 1 hr and continued to 16 hrs., but not with its metabolites. These results strongly suggest that DHEA or possibly another yet to be identified metabolite might be responsible for peroxisome proliferation.

Sex steroid receptors in normal and hyperplastic human prostate

The concentrations of sex steroid receptors (per unit DNA) were measured in normal periurethral and peripheral prostatic tissue samples from seven men (mean age 64 years; range 54-71 years) undergoing cystectomy for bladder cancer, and in hyperplastic nodules from 15 men with BPH (mean age 69 years; range 60-89). Occupied androgen (AR) and estrogen (ER) receptors were measured with an improved exchange procedure, where receptor-binding sites were stabilized by a combinatorial procedure involving careful washout of extracellular secretory products (including proteases) prior to homogenization, inclusion of 0.5 mM phenylmethyl sulfonylfluoride (PMSF) and 20 mM molybdate in the exchange medium, and long-term incubation at 0-4 degrees C. Bound radioligands were separated by a hydroxylapatite (HAP) batch adsorption procedure. Maximal specific exchange binding of 3H-R 1881 or 3H-estradiol in total homogenates of human prostate samples was achieved after incubation periods of about 72 h at 0-4 degrees C. In contrast, progestin receptors (PR) were readily available for binding 3H-R 5020; thus overnight binding at 0-4 degrees C was routinely used to measure PR. Binding specificities and equilibrium binding constants (calculated from 8-point Scatchard plots, correcting for nonsaturable binding) were found to be characteristic for AR, PR, and ER, respectively. The receptor results obtained in this study demonstrate that no significant differences existed in total AR per unit DNA between hyperplastic and either central or peripheral prostatic tissue samples; PR was present in both zones of normal prostatic tissue as often as in BPH samples, with PR concentrations significantly lower in hyperplastic samples; and ER was irregularly detected in both normal and hyperplastic tissue in low concentration relative to AR and PR; the frequency of ER detection was much lower in BPH than in normal prostate tissue. Studies of steroid receptor content relative to enzyme markers specific for epithelial and stromal cells in BPH samples showed a positive correlation between acid phosphatase activity (a specific marker for epithelial cells) and both AR and PR. No correlation was observed between AR or PR with either prolyl hydroxylase or myosin ATPase (specific markers for stromal cells). These observations suggest that PR, as well as AR, is primarily associated with the epithelial elements of prostate. Because of the relative infrequency of ER, similar correlation of ER with enzyme markers was not possible.

Susceptibility of the prostate cancer cell to different physical, hormonal, and chemical agents: present status and theoretical prospects for improved prostate cancer therapy

The benefits and limitations of present modes of treatment of prostatic cancer with physical, hormonal, and chemical agents are briefly reviewed. The theoretical possibility that the heterogeneous clones that comprise prostatic cancer might be killed or controlled by selective targeting of cytotoxic agents (actual or potential) to malignant cells is discussed in terms of two types of delivery vehicles to provide for cell selectivity: (1) monoclonal antibodies against specific cell surface markers on cancer cells and (2) steroid ligands for receptors present in clones of malignant cells. The problems and prospects of these selective delivery systems as potential therapeutic modalities for prostatic cancer are considered.

Characteristics of separated epithelial and stromal subfractions of prostate: I. Rat ventral prostate

These studies were initiated with the objective of isolating epithelial and stromal cells of human prostatic tissue in undamaged state, in order to study the cellular distribution of steroid receptors in benign prostatic hyperplasia (BPH) relative to normal prostate. Initial experiments showed that when BPH tissue immersed in tissue culture media was progressively fragmented by various cutting procedures, epithelial elements were selectively released as clumps of variable size and individual cells, but that a large percentage of these cells were damaged, as evidenced by their failure to exclude trypan blue (TB). These observations suggested that if tissue fragmentation were carried out under defined conditions that minimize cell damage, BPH subfractions might be obtained containing a large percentage of undamaged cells. To determine conditions of tissue fragmentation which result in maximal recovery of epithelial cells which exclude TB, rat ventral prostate (RVP) was chosen as a model system. Experiments with RVP revealed that maximal yields of such cells were obtained in "large" epithelial clumps (greater than 30 cells per clump) released under the following conditions: (1) chopping the tissue with razor blades in a large volume (2 ml/100 mg RVP) of a Ca2+-free tissue culture medium ( Joklik 's-MEM) containing 1% casein, (2) carrying out the entire fractionation procedure in the cold, and (3) maintaining a 1% casein concentration in the medium during chopping, as well as in subsequent washing procedures, to protect cells from proteolytic activity. In large epithelial clumps, cells in the interior of the clump were not stained by TB but the cells at the periphery of the clump were freely permeable to TB. Single epithelial cells and small epithelial clumps (3-10 cells) released by razor blade fragmentation were also permeable to TB. When large epithelial clumps were incubated at 20 degrees C for 90 min, the clumps disaggregated into smaller clumps and morphologically intact single cells, which did not exclude TB. The residual tissue fragments remaining after chopping contained the bulk of stromal cells plus some epithelial elements. The latter could be removed by gentle rubbing of the fragments on a sieve in the presence of medium. The stromal fraction thus obtained consisted of stromal cells, embedded in mesenchymal matrix, which were not stained by TB and appeared normal when examined histologically by light microscopy.(ABSTRACT TRUNCATED AT 400 WORDS)

Characteristics of separated epithelial and stromal subfractions of prostate: II. Human prostate

Surgical samples of human benign prostatic hyperplasia tissue (BPH) were fractionated into epithelial clumps and stromal fractions, using the "optimal" tissue dissociation procedure developed for rat prostate described in the preceding report. The separated cellular fractions were compared to control unfractionated tissue (wherein extracellular secretory products had been removed) with respect to the concentrations of androgen receptor and enzyme markers on a DNA basis; cell damage was also evaluated by light and electron microscopy (EM). EM revealed extensive cell damage in epithelial clumps and stromal fractions, which had appeared normal when examined by light microscopy. Damage to the ultrastructure of individual epithelial cells present in clump fractions was very variable, involving vacuolization of the cytoplasm and condensation of nuclear chromatin in some cells, vacuolization of just the cytoplasm in other cells; only a small fraction of the cells in clumps had normal ultrastructure. Ultrastructural damage to stromal cells was much greater in fibroblasts than in muscle fibers. The cell damage observed in both subfractions of human prostate was associated with a marked degree of receptor loss. The mean decreases in the number of androgen receptors per unit DNA relative to control unfractionated tissue was 68.5 and 62.5% recovered in epithelial and stromal fractions, respectively. Measurement of various enzymes as "markers" revealed that acid phosphatase activity (per unit DNA) was associated exclusively with the epithelial clump fraction. Prolyl hydroxylase and myosin ATPase activities (per unit DNA) were restricted to the stromal fraction. The limitations of using mechanically separated subfractions of human prostate tissue for evaluation of the cellular distribution or the initial concentration of steroid receptors in human prostate tissue are discussed.

Androgen receptors in rat and human prostate

In intact adult rats almost all androgen receptor (AR) sites of the rat ventral prostate (RVP) are occupied by endogenous dihydrotestosterone, and about 80% of these sites are nuclear. Nuclear AR disappears rapidly after castration (half-life of 3 h). The amount of cytosolic AR does not change within the initial 36 h, then markedly decreases during the next 2-5 days. An early and specific action of androgen is a remarkable increase of its own receptor. RVP also contains an estradiol receptor (ER) which rapidly disappears after castration and which, contrary to AR, is predominantly localized in the cytosol of stromal elements. The published procedures for steroid receptors grossly underestimate receptors concentrations in normal (NHP) and hyperplastic (BPH) human prostate. We have recently established a reliable method for the measurement of total AR, and we have found no difference in AR concentrations between NHP and BPH. BPH also contains a progesterone receptor and an elusive ER. Finally, we have used specific immunoglobulins in sex hormone binding plasma protein (SBP) for the demonstration of SBP-like immunoreactivity by the indirect immunofluorescence technique. The specific antigenic material was exclusively localized in the cytoplasm of BPH epithelial cells.

Androgen and estrogen receptors in rat ventral prostate epithelium and stroma

Estrogen and androgen receptors have been investigated in rat ventral prostate epithelium and stoma. High speed supernatants were prepared from unfractionated or fractionated prostates. Cytosols from intact rats were incubated with 2 nM 3H-estradiol (E2) in presence of 80 nM dihydrotestosterone (DHT), and cytosols from 1 day castrated rats were incubated with 2 nM 3H-DHT, at 0 C for 4 h. They were submitted to ultracentrifugation on glycerol-Tris gradients. The amounts of hormones bound to the saturable 8S binding components were determined on a comparative basis. The values for E2-receptor in intact rats were 2.3, 15.4 and 5.9 fmol/mg cytosol protein in unfractionated prostate, stroma and epithelium, respectively. The corresponding values for DHT-binding were 31.9, 17.2 and 29.2 fmol/mg protein. In addition, Scatchard analysis of saturable E2 and DHT binding, using the protamine precipitation technique, essentially confirmed the results of glycerol gradients, and led to the conclusion that, contrary to androgen receptor, the major part of estradiol receptor is localized in stroma.

Oxytocin receptors coupled to uterine contraction in estrogen-dominated rabbits

The present study investigated whether specific [3H]oxytocin binding sites previously demonstrated in estrogen-dominated rabbit uterus have properties expected of physiologic receptors coupled to uterine contraction. Microsomal membranes from estrogen-dominated rabbit uterus were found to contain high-affinity specific oxytocin binding sites with Kd = 2-3 nM. These sites were predominantly myometrial in locus. Specific oxytocin binding exhibited a pH optimum between 7.5 and 8.0. Mg2+ or Mn2+ was necessary for maximal specific [3H]oxytocin binding; in contrast, Ca2+ at submillimolar concentrations inhibited specific binding. Oxytocin binding sites were not detectable in microsomal membranes isolated from progesterone-dominated rabbit uterus. Relative binding and uterotonic activities of 10 synthetic neurohypophyseal hormone analogues were determined in estrogen-dominated rabbit uterus. A qualitative correlation was observed between binding and uterotonic responses. Angiotensin II and insulin did not compete with [3H]oxytocin for uterine binding sites. It is concluded that the specific high affinity [3H]oxytocin binding sites demonstrated in estrogen-dominated rabbit uterus have the selectivity for neurohypophyseal hormone analogues expected for physiologic receptors coupled to uterine contraction.

Effects of oxytocin and methacholine on cyclic nucleotide levels of rabbit myometrium

The effects of oxytocin and methacholine on cyclic nucleotide levels in estrogen-primed rabbit myometrium were studied in the presence and absence of 1-methyl-3-isobutyl xanthine (MIX), a phosphodiesterase inhibitor. In the absence of MIX, methacholine increased guanosine 3',5'-cyclic monophosphate (cGMP) levels at a time when contraction was decreasing, but had no influence on adenosine 3',5'-cyclic monophosphate (cAMP) levels. In contrast, oxytocin did not elevate cGMP, but rapidly decreased cAMP levels. MIX (1 mM) increased both cAMP and cGMP levels. Oxytocin or methacholine further increased cGMP, indicating activation of guanylate cyclase. Oxytocin- but not methacholine-induced stimulation of guanylate cyclase was abolished in Ca2+-free solution. Oxytocin increased cAMP over the levels produced by MIX alone, whereas methacholine decreased cAMP below the MIX control values; these effects were insensitive to indomethacin. Tissue levels of cGMP and cAMP did not directly correlate with isometric tension. The results also indicate that both oxytocin and methacholine stimulate guanylate cyclase but have opposing effects on adenylate cyclase of rabbit myometrium.

Neurohypophyseal hormone-responsive renal adenylate cyclase. IV. A random-hit matrix model for coupline in a hormone-sensitive adenylate cyclase system

A "random-hit" matrix model is proposed to account for the dynamic and steady state relationship between occupation of bovine renal medullary membrane receptors by [Lys8]vasopressin (LVP) and neurohypophyseal hormones (NHH) and the associated activation of membrane-bound adenylate cyclase. The model was developed by systematic introduction of specific rules concerning receptor coupling into a general structural model which consists of two square matrices of identical size, one composed of homogeneous R ("receptor") units, the second of homogeneous C ("cyclase") units. R units are either occupied (RO) or unoccupied (RU); C units are either active (CA) or inactive (CI). Hormone molecules are envisioned to "collide" with R units randomly; collision with RU leads to "binding", and occupation is maintained for a characteristic mean occupancy time, TO. In this structure, each R unit has an "interaction field" which consists of the "twin" unit in the "C" matrix, and the 4 nearest neighbor C units surrounding the twin. Occupation of an R unit leads to activation of all CI units in the interaction field of that R; CA units in the interaction field are refractory. Thus binding at a given R may "recruit" a variable number of inactive neighboring C units (5, 4, 3, 2, 1, or 0). The model requires that there be individual coupling delays between the moment of binding at a given R and subsequent activation of CI units (mean coupling delay (Td) approximately 10% To). Activation of C units persists as long as the "parent" R is occupied and is maintained for an additional short time interval (Tp) after RO reverts to RU, corresponding to hormone dissociation from receptor. The model accounts for the following previously demonstrated relations between LVP occupation of receptors and adenylate cyclase activation in bovine renal medullary membranes: 1) the shape of the nonlinear steady state relation between normalized (percentage maximal) receptor occupation (O) and cyclase activation (A), uniformly observed in different membrane preparations: 2) variable hormone concentration-dependent trajectories of approach to the final steady state A:O value (A:Oss) which may be either monophasic or biphasic; 3) the loss of intrinsic adenylate cyclase activity observed in bovine membranes for a series of NHH analogs with progressively diminishing affinity for receptors. The model represents an explicit theory of coupling where a successive series of temporal events are quantitatively related to each other and privide major constraints to any interpretation of the molecular organization of receptors and adenylate cyclase units in membranes. The model excludes a number of mechanistic proposals and suggests a new hypothesis for membrane coupling with features which may be generally applicable to other hormone-sensitive adenylate cyclase systems.

Opposing effects of estradiol and progesterone on oxytocin receptors in rabbit uterus

Estradiol-17beta administration to young (10- to 12-week-old) rabbits to produce the "estrogen-dominated" uterus increased the uterine contractile response to both oxytocin and methacholine in vitro. In "progesterone-dominated" uteri, obtained from rabbits that received progesterone for 4 days after estrogen pretreatment, the contractile response to oxytocin in vitro was selectively abolished; the response to methacholine was unaffected. Parallel changes were observed in the concentration (but not affinity) of specific sites in uterine microsomal membranes that bind [(3)H]oxytocin with selectivity features expected for oxytocin receptors. Thus, estrogen-dominated uteri have an increased number of specific [(3)H]oxytocin binding sites per mg of membrane protein relative to untreated controls, whereas specific oxytocin binding sites are reduced to barely detectable levels in the progesterone-dominated uterus. Similar results are obtained when binding sites are measured in membranes from the myometrium of estrogen- or progesterone-dominated uteri. Short-term (24-hr) progesterone administration to estrogen-pretreated rabbits decreased, but did not abolish, specific [(3)H]oxytocin binding; the concentration of specific [(3)H]oxytocin binding sites was reduced without influence on the affinity of these sites. A sublethal dose of actinomycin D, administered over a 24-hr period to rabbits pretreated with estradiol for 4 days, likewise reduced specific oxytocin binding; additive effects were not observed when progesterone and actinomycin D were administered together. These results suggest that the regulatory effects of estrogens and progesterone upon the rabbit uterine contractile response to oxytocin are achieved, at least in part, by the opposing actions of these steroids in regulating the number of oxytocin receptors in smooth muscle cells. Estradiol increased the concentration of uterine oxytocin receptors; the maintenance of high receptor levels appears to depend upon the continuous de novo synthesis of oxytocin receptors. In contrast, progesterone, like actinomycin D, appears to act at the nuclear locus to repress synthesis of oxytocin receptors.

The receptor concept: prejudice, prediction, and paradox

Major progress has been achieved in understanding the chemical nature of receptors for certain hormones and neurotransmitters. Some of these units have been obtained as homogenous proteins; concept and technology are adequate to permit the detailed chemical and structural analysis of these macromolecular units. The critical problem which now arises is to define how a receptor once "occupied" and "activated" serves to initiate action. Elucidation of details of receptor structure, in of itself, will not solve the "coupling problem" in hormone action. New concepts, as well as new technics, will probably be necessary. In this discussion I have raised the possibility that metals coordinated to hormone receptor complexes may be the "trigger" element involved in initiating action, serving to alter the state of functional units in binary fashion. In effect, the metal determines whether the "state" of the system is active or inactive. As stated previously in connection with the action of steroid hormone receptor complexes, the specific suggestions made relating metals to the hormone coulping process have been advanced primarily to illustrate the conceptual gap which exists with respect to "coupling." The present suggestions may prove to be correct or untenable, in whole or in part. If it turns out that metals play a central role in the coupling process of hormone action, perhaps via completely different mechanisms than those suggested here, one of the central ideas of receptor action developed by the pioneers who created the receptor concept will have been resurrected in principle, if not in detail. In science, as in life generally, conceptual progress once achieved sometimes turns out to be the rediscovery of the past.

Iodinated neurohypophyseal hormones as potential ligands for receptor binding and intermediates in synthesis of tritiated hormones

[3-Iodo-Tyr2]oxytocin (MIOT), [3,5-diiodo-Tyr2]oxytocin (DIOT), [3-iodo-Tyr2,Lys8]vasopressin (MILVP), [3,5-diiodo-Tyr2,Lys8]vasopressin (DILVP), [3-iodo-Tyr2,Arg8]vasopressin (MIAVP), and [3,5-diiodo-Tyr2,Arg8]vasopressin (DIAVP) were synthesized by iodination of the respective hormones, pruified, and characterized. All the monoiodo hormones had to be freshly prepared prior to bioassays, since on storage they gave rise to hormonal-like biological activity. The biological activities of these iodo analogues were measured in an adenylate cyclase assay employing neurohypophyseal hormone (NHH) sensitive bovine renal medullary membranes, and/or the rat oxytocic assay. In the cyclase assay, DIOT, DILVP, and DIAVP were inactive as agonists or antagonists. MIOT shows no agonistic activity in the renal cyclase system and uterus, but is a weak reversible inhibitor of oxytocin (OT) in both systems. When MIOT (10(-4) M) was preincubated with renal membranes for 10 min at 37 degrees C before addition of OT, it behaved as a noncompetitive inhibitor of NHH-stimulated adenylate cyclase. MILVP and MIAVP appear to be partial agonists with Km (half maximal response) 3 X 10(-6) and 3 X 10(-7) M, respectively, as determined in the cyclase assay. Upon preincubation with renal medullary membranes, MILVP (10(-6) M) behaves as a more potent noncompetitive inhibitor of OT than MIOT. Accordingly, iodo derivatives of NHH do not exhibit sufficient affinity to serve an specific ligands to measure OT, LVP, or AVP receptors in the uterus and kidney. Study of the specificity of inhibition produced by MIOT revealed that this analogue does not act selectively upon NHH receptors. Thus, MIOT modified adenylate cyclase systems which do not have NHH receptors, e.g., the PTH-sensitive adenylate cyclase in bovine renal cortex and the glucagon-sensitive adenylate cyclase in rat liver. DIOT, DILVP, and DIAVP were subjected to catalytic tritiation (employing carrier free tritium) and were converted to [3H]OT (25, 31, and 25 Ci/mmol), [3H]LVP (26 and 23 Ci/mmol), and [3H]AVP (17 Ci/mmol), respectively. These tritiated ligands have been successfully used to measure NHH receptor sites both in kidney and uterine membranes as described in other studies.

Failure to observe testosterone-induced nucleus-lysosome interaction in rat ventral prostate

The possibility that sex steroids act to promote the association of lysosomes with nuclei was studied by 2 methods in the secretory epithelium of ventral prostate of castrated rats treated with androgens: (a) electron microscopic (EM) examination of intact tissue and (b) study of fresh nuclear suspensions isolated from prostate homogenates using the fluorescing dye acridine orange (AO) and EM. AO-stained particles in nuclear suspensions were found to correspond to either (i) section granules, (ii) primary lysosomes or (iii) heterogenous dense bodies (HDB), considered to be lysosomes. Intact prostate tissue and crude nuclear suspensions were studied in adult rats 3-21 days after castration and in normal rats. Changes in nuclear architecture are evident 8 days or more after castration; the number of HDB increase while secretion granules and primary lysosomes decrease. Whether from prostate of castrated, normal or hormone-treated animals, a small number of the lysosomal HDB or primary lysosomes are seen closely apposed to epithelial cell nuclei. In response to short-term testosterone administration (15 or 60 min) in 10- and 21-day castrate rats, chromatin distribution appears to become more condensed; yet the number of associations of nuclei with lysosomal elements does not change. These studies of androgen action in rat ventral prostate (a classical target organ for the study of androgen action) provide no evidence to support the idea that lysosomal association with, or invasion of, nuclei in target cells is a general feature of sex steroid hormone action.

Contribution of the peptide backbone to the action of oxytocin analogs

This investigation was undertaken to evaluate the functional contribution of the peptide backbone of oxytocin in its interaction with receptor. Corey-Pauling-Koltun models of (Gly-7) deaminooxytocin, deaminotocinamide, and their respective retro-D-analogs built in any specific conformation (e.g., the Walter-Urry model for oxytocin) have a quai-equivalent topochemical arrangement of amino-acid side chains; however, the CO and NH elements of the peptide backbone of the retro-D-analog are reversed. The retro-D-analogs of deaminotocinamide and (Gly-7) deaminooxytocin (prepared using D-alle for L-Ile) and their respective N-formyl derivatives were assayed for uterotonic activity relative to related L-peptides. All retro-D-analogs (tested at concentrations ranging from 10-10 to 10-5 M) were devoid of angonistic (or antagonistic) activity in the isolated rat uterus, except for the retro-D-(D-alle-3, Gly-7) deaminooxytocinamine, which retains a terminal NH-2 group on the tail; the latter is a partial agonist with very low affinity. The results obtained with retro-D-analogs indicate that one or more of the elements of the peptide backbone of the tocinamide ring are essential for "occupation" and "activation" of uterine receptors. Oxytocin action may be the resultant of multiple hydrogen-bonding interactions between CO, NH, NH-2, and OH groups of the hormone with complementary groups on receptor, made possible by appropriate hydrophobic bonding.

Neurohypophyseal hormone-responsive adenylate cyclase from mammalian kidney

The investigation was undertaken to evaluate the direct stimulatory effects of neurohypophyseal hormones upon adenylate cyclase activity in a cell-free, particulate fraction derived from the kidney medulla of various mammalian species. The relative affinity of neurohypophyseal hormones for the receptor component of the adenylate cyclase system (as defined by the concentration of hormone required for half-maximal stimulation) had the order [8-arginine]-vasopressin > [8-lysine]-vasopressin >> oxytocin (AVP > LVP >> OT) for rat, mouse, rabbit, and ox; in the pig, the order was LVP > AVP >> OT. The relative affinities of the three hormones in rat and pig cyclase systems were found to correspond with the relative antidiuretic potencies of these hormones in the intact rat and pig. These findings show that the renal receptor for neurohypophyseal hormones in a particular species exhibits the highest affinity for the specific antidiuretic hormone that occurs naturally in that species. Some of the molecular requirements for the stimulation of rabbit adenylate cyclase were defined by studies of several neurohypophyseal analogs possessing structural changes in positions 1, 2, 3, 4, 5, 8, and 9. This investigation introduces the particulate preparation of renal medullary adenylate cyclase as a tool for the analysis of neurohypophyseal hormone-receptor interactions and indicates that this preparation can be adapted to serve as an in vitro bioassay system for antidiuretic hormonal activity.

Insulin and microtubules in rat adipocytes

Insulin appears to promote microtubule assemblty in rat adipocytes. Neithler oxytocin nor high concentrations of glucose has this effect. Colchicine inihibits stimulation by insulin of lipid and glycogen synthesis without influencing stimulation by insulin of glucose oxidation. The anabolic effects of oxytocin or high concentrations of glucose are not inhibited by colchicine. The "directive effect" of insulin may involve microtubules.

Neurohypophyseal hormone-sensitive adenyl cyclase of toad urinary bladder

An adenyl cyclase preparation derived from epithelial cells of the urinary bladder of the toad, Bufo marinus, is described. This cyclase preparation is specifically stimulated by neurohypophyseal hormones and various synthetic analogs which evoke a hydroosmotic response in the intact bladder. The relative stimulatory effects of these compounds have been compared on the cyclase preparation and in the intact bladder. The peptide concentrations required for half-maximal stimulation (affinity) in the cell-free and intact systems were parallel; however the magnitude of stimulation produced by saturating concentrations of peptides did not correlate. Furthermore, it was found that peptide analogs which inhibit the hydroosmotic effect of [8-arginine]-vasopressin on the intact bladder also inhibit the stimulation of the toad bladder cyclase preparation by vasopressin. Prostaglandin E(1), mercaptans, and disulfides, which inhibit the hormone-induced hydroosmotic response of the intact bladder, did not antagonize the stimulation of the toad bladder cyclase preparation by vasopressin.

Glucocorticoid regulation of ACTH sensitivity of adenyl cyclase in rat fat cell membranes

Plasma membrane sacs of isolated rat fat cells (ghots) possess an adenyl cyclase system, which is activated by lipolytic hormones of disparate molecular structure, including adrenocorticotropin (ACTH), glucagon, and epinephrine. Previous studies indicated that distinctive selectivity units for individual hormones are coupled to the same unit of adenyl cyclase in the fat cell membrane. The present study has shown that ghost cyclase from adrenalectomized and hypophysectomized rats exhibits a striking reduction in response to ACTH, the stimulatory effects of epinephrine, glucagon, or fluoride being unchanged. Pretreatment of adrenalectomized, hypophysectomized, sham operated, or intact rats with the synthetic glucocorticoid, dexamethasone, selectively increased the ACTH response in ghost cyclase preparations. Cortisol, like dexamethasone, increased the ACTH response in ghosts from adrenalectomized rats; 11-deoxycorticosterone was ineffective. The dexamethasone effect to enhance the ACTH response is blocked by actinomycin D or cycloheximide. The present results show that stimulation of rat fat cell adenyl cyclase by ACTH involves a distinctive molecular entity, which can be clearly differentiated from adenyl cyclase in the membrane as well as from the selectivity sites for epinephrine and glucagon. The data indicate that the biosynthesis of the component required for ACTH stimulation of ghost cyclase-either an ACTH selectivity unit or specific coupling factor-is induced by glucocorticoids at the level of gene regulation.