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Biomedical subjects

R Schulz

Publications and source records attributed to R Schulz.

At least 523 records · Page 29Linked to original sources
PubMed1985

Opioid dependence prevents the action of pertussis toxin in the guinea-pig myenteric plexus.

The longitudinal muscle-myenteric plexus preparation of the guinea-pig ileum has been employed for the study of the effect of pertussis toxin (IAP) on opioid dependence. Guinea-pigs were treated with IAP (120 micrograms/kg, i.p.) either prior to chronic administration of an opioid or after opioid dependence had been established. The isolated preparations were tested in vitro for dependence; that is, the naloxone-precipitated withdrawal contracture. Naloxone almost failed to evoke a sign of dependence in preparations treated with IAP prior to chronic exposure to an opioid. In contrast, IAP failed to affect the withdrawal contracture when applied to an animal after dependence has been established. It is concluded that the Ni-unit, the substrate for IAP, plays a critical function in the development of dependence. The continuous activation of the opioid receptor associated with the development of dependence may induce changes in Ni which in turn prevent the interaction of IAP with its substrate.

Animals↗
PubMed1985

RIA determination and immunofluorescence localization of cyclic nucleotides in rainbow trout (Salmo gairdneri) testes.

Using histological criteria, testicular development was divided into six stages (I-Va). The testicular amounts of 3',5'-cyclic adenosine- and guanosine monophosphate (cAMP, cGMP) were determined radioimmunologically, and their testicular distribution patterns were monitored by indirect immunofluorescence microscopy. During slow testicular growth (stages I-III), the nucleotide concentrations were high (0.62-1.2 pmol cAMP/mg, 0.17-0.24 pmol cGMP/mg). With the appearance of spermatozoa in stage IV, they fell to low levels which were maintained with some fluctuations until the end of the cycle (0.05-0.1 pmol cAMP/mg, 0.016-0.05 pmol cGMP/mg). The cAMP antiserum intensely stained spermatogonia, a portion of the spermatocytes, and spermatids. Spermatozoa showed almost no staining. Fluorescence labeling of somatic cells was observed in immature testes and during spermiation. Except for staining all spermatocytes, the same pattern was observed using the cGMP antiserum.

Animals↗
PubMed1985

Excitatory neuropeptides activate opioid mechanisms in the guinea pig ileum.

A variety of peptides (corticotropin releasing factor (= CRF), cholecystokinin-derived peptides, neurotensin, bombesin, angiotensin II, bradykinin and substance P) induce a contraction of the myenteric plexus/longitudinal muscle preparation of the guinea-pig ileum. This excitatory effect is rapid in onset and disappears within a few minutes in the continued presence of the peptide. A part of the contractile response is antagonized by atropine indicating that acetylcholine (ACh) is involved in this effect. Following cessation of the peptide-induced contraction, a second contractile response can be elicited by the opioid antagonist naloxone. The magnitude of this naloxone induced contraction is related to the "atropine-sensitive" component of the initial contractory effect of the peptides. It appears that the peptidergic excitatory action on the plexus which is associated with release of ACh, initiates the release of opioid peptides in this tissue.

Angiotensin II↗
PubMed1985

Long-term adjustment to physical disability: the role of social support, perceived control, and self-blame.

One hundred middle-aged and elderly spinal-cord-injured persons were interviewed an average of 20 years after the disability occurred. Respondents answered questions concerning perceived control, attributions of blame, and the nature of the social comparisons they made. Three existing standardized instruments were used to measure adjustment: Index of Psychological Well-Being, Life Satisfaction Index, and the Center for Epidemiologic Studies Depression Scale. For all three outcome measures, respondents reported levels of well-being only slightly lower than population means of nondisabled persons of similar age. Controlling for health status and current income, we found that persons who have high levels of social support, who are satisfied with their social contacts, and who feel they have high levels of perceived control report high levels of well-being. Self-blame and the perceived avoidability of the cause of the disability correlated only moderately with the three measures of adjustment, suggesting that there are important differences between coping successfully immediately after a traumatic event has occurred and coping successfully many years later.

Adaptation, Psychological↗
PubMed1985

Sex-dependent endorphinergic and adrenergic control mechanisms of luteinizing hormone secretion in immature rats.

Previous studies in male and female immature rats have revealed striking sex differences as concerns endorphinergic and adrenergic control of luteinizing hormone (LH) secretion. The present study examines in 10 days old male and females rats whether these differences result from sexual differentiation of the brain, or acute effects of male and female gonadal hormones. The techniques employed to manipulate these mechanisms were gonadectomy immediately post-partum and androgenization. Androgenization on the 1st and 2nd day of life reduces the ability of naloxone to elevate serum LH levels in females, but failed to modify the LH-elevating effect of clonidine in males. Experiments with castrates showed that testosterone is critical for these sex-related differences. Treatment with testosterone on the 9th day of life of intact or gonadectomized rats revealed the ability of this hormone to modify LH-release acutely. We conclude that sexual differentiation of the brain may be of minor significance for the sex-related LH-control mechanisms in prepubertal rats. Of importance is the acute presence of testosterone, since in its absence male characteristics disappear.

Animals↗
PubMed1985

On the role of energy metabolism in Neurospora circadian clock function.

Neurospora crassa (bdA) mycelia were kept in liquid culture. Without rhythmic conidiation the levels of adenine nucleotides undergo circadian changes in constant darkness. Maxima occur 12-17 hr and 33-35 hr after initiation of the rhythm, i.e., at CT 0-6 hr. Pulses of metabolic inhibitors such as vanadate (Na3Vo4), molybdate (Na2MoO4 : 2 H2O), N-ethylmaleimide (NEM), azide (NaN3), cyanide (NaCN) and oligomycin phase shift the circadian conidiation rhythm of Neurospora crassa. Maximal advance phase shifts are observed at about CT 6 with all inhibitors. Pulses of N,N'dicyclohexylcarbodiimide (DCCD) and light phase shift the conidiation rhythm following a phase response curve different from those of the other agents (maximal advance at about CT 18-24). The phase shifts with DCCD and light are significantly larger in the wild type compared to the mitochrondrial mutant poky. Such differences are not found in PRCs of the protein synthesis inhibitor cycloheximide. [31P] NMR spectra of wild type Neurospora crassa and the clock mutants frq 1 and frq 7 which differ in their circadian period lengths did not reveal differences in the concentrations of adenine nucleotides, pyridine nucleotides or sugar phosphates. Starvation causes drastic changes of the levels of adenine nucleotides, phosphate and mobile polyphosphate without effecting phase or period length of the circadian rhythm.

Adenine Nucleotides↗
PubMed1985

Correlates of life satisfaction and depression in middle-aged and elderly spinal cord-injured persons.

Advances in health care science allow more people with spinal cord injuries to live to old age. The purpose of this study was to determine those factors that contribute to the well-being of middle-aged and elderly spinal cord-injured people. One hundred spinal cord-injured people, ranging in age from 40 to 73 years, completed an extensive structured interview. In general, respondents reported a degree of well-being on the same measures of satisfaction and depression that was slightly lower than that of similarly aged nondisabled people. Pearson correlations indicated that people experiencing high levels of well-being reported high levels of perceived control, had higher levels of social support, and judged their health status to be good. These people also viewed their disability more favorably, tended to have higher incomes and more education, were employed, and were more religious than those indicating lower levels of well-being. The severity of the spinal cord injury was not correlated highly with subjective well-being, although there was a tendency for those with greater disability to report lower levels of well-being. People who were younger, who incurred their disability at a younger age, and who blamed themselves and felt they could have avoided the injury also tended to report higher levels of well-being.

Adult↗
PubMed1985

[Endogenous opioids].

The discovery of the opioid receptors and their corresponding ligands, the opioid peptides, is of fundamental importance as regards our understanding of a variety of functional mechanisms in the central and peripheral nervous system. This review considers the distribution of the multiple opioid peptides within the organism as well as their tissue-specific enzymatic processing. These parameters differ considerably between species. The multiple opioid peptides are paralleled by multiple opioid receptors. These opioid systems affect a broad spectrum of functions, such as behaviour, pain perception, the cardiovascular system, respiration, appetite, gut motility and secretion, water- and electrolyte balance and the complex field of endocrine mechanisms. The task of future pharmacological research is to study these functions by means of more selective opioid agonists and antagonists. An awareness of our present knowledge and of probable findings to come suggests novel therapeutic possibilities in the field of veterinary science.

Animals↗
PubMed1985

Evidence for the epsilon-type of opioid receptor in the rat vas deferens.

The epsilon-opioid receptor type has been postulated to be specific for beta-endorphin on the basis of structure-activity studies in the isolated rat vas deferens (RVD). Since beta-endorphin also displays high affinity for other opioid receptors, the present investigations were conducted to better define the epsilon-receptor in the RVD. Therefore, the interaction of concomitantly acting pairs of opioid agonists was examined and analyzed according to the predictions of the law of mass action and the receptor theory. Our data provide evidence for a specific receptor for beta-endorphin in this organ, a receptor not recognized by either the delta-agonist D-Ala2-D-Leu5-enkephalin, or the mu-agonists FK-33824, fentanyl, and etorphine in the range of concentrations necessary for them to exert maximal inhibition of electrically induced twitch tension. The activity displayed by beta-endorphin in the RVD is in agreement with the existence of the proposed epsilon-type of opioid receptor therein.

Animals↗
PubMed1984

Intracerebral injection of different antibodies against endogenous opioids suggests alpha-neoendorphin participation in control of feeding behaviour.

The mechanism of feeding behaviour of rats was examined. We used antibodies to different opioid peptides in order to reduce the tonic activity of various endogenous opioid peptide systems that may underly appetite. Unilateral microinjection of anti-alpha-neoendorphin antibodies into various areas of the ventromedial hypothalamus (VMH) inhibited food and water intake up to 45% in deprived animals. Injections outside this area failed to affect feeding. Administration of anti-beta-endorphin antibodies into the VMH moderately attenuated appetite. A considerable decrease of food and water intake was observed only upon injection of this antibody into the nucleus periventricularis hypothalami, a region generally believed to be involved with feeding. A marginal reduction of appetite was observed with anti-dynorphin antibodies injected into the VMH. These data may suggest that alpha-neoendorphin is involved in the control of food and water intake in the VMH.

Animals↗
PubMed1984

Serum levels of 11-oxotestosterone in male and 17 beta-estradiol in female rainbow trout (Salmo gairdneri) during the first reproductive cycle.

From September 1980 to August 1981 the serum levels of 11-oxotestosterone (11-O-T) in 231 male and of 17 beta-estradiol (E2) in 207 female rainbow trout were measured radioimmunologically, and compared with the development stages of the gonads. Using histological criteria, testicular development was divided into seven stages, and ovarian development into four stages. In males, 11-O-T levels remained below 6 ng/ml until the appearance of spermatozoa. Maximum values (126 ng/ml) were observed in spermiating males. In females, E2 levels were below 2 ng/ml during the period of slow oocyte growth. Maximum values (average of 31 ng/ml) were observed during exogenous vitellogenesis.

Animals↗
PubMed1984

A receptor preparation from testes of Salmo gairdneri (Richardson): in vitro binding studies with 125I-labeled hCG and trout pituitary proteins.

A gonadotropin-receptor preparation from trout during full spermatogenesis known to bind 125I-hCG was used to test the ability of trout pituitary proteins to dislocate hCG from the receptors. From the proteins of male trout pituitaries chromatographed on immobilized concanavalin A, only the glycoprotein fraction was able to compete with hCG for the receptors. Unabsorbed proteins eluting in three fractions were radioiodinated and used as ligands. The fact that they were not taken up specifically by the receptor preparation, and the competition of the glycoproteins with 125I-hCG, is discussed in the context of the vertebrate's gonadotropic hormone system.

Animals↗
PubMed1984

Application of receptor theory provides further evidence for the existence of the epsilon-opioid receptor in rat vas deferens.

In the present study, we analyzed the interaction of concomitantly-acting pairs of opioid agonists in inhibiting the electrically induced contraction of the rat vas deferens (RVD). The results when compared with the predictions of the law of mass action and the receptor theory (1,2) provide evidence for a specific receptor for beta-endorphin (beta-EP) in this organ. This receptor is not occupied by the delta-agonist D-Ala2-D-Leu5-enkephalin (DADLE), or the mu-agonists Sandoz FK-33824, fentanyl and etorphine in the range of concentrations necessary for these to exert their maximal agonistic action in the test. The activity of beta-endorphin in the rat vas deferens is in agreement with the proposed existence (3,4) of the epsilon-type of opioid receptor therein.

Animals↗
PubMed1984

Anti-idiotypic opioid receptor antibodies.

Anti-idiotypic antibodies were raised against the monoclonal antibody 3-E7. One of these anti-idiotypic antibodies interferes with the binding of 3H-diprenorphine at solubilized opioid receptors, and exhibits opioid agonistic activity on NG108CC15 hybrid cells.

Animals↗