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Biomedical subjects

R L Moss

Publications and source records attributed to R L Moss.

At least 199 records · Page 11Linked to original sources
PubMed1985

Hormonal modulation of the responsiveness of midbrain central gray neurons to LH-RH.

The spontaneous firing rate of midbrain central gray (MCG) neurons and the effect of iontophoretically applied prolactin and luteinizing hormone releasing hormone (LH-RH) on the electrical activity of these neurons was studied in untreated and estrogen-progesterone-treated ovariectomized female rats. The spontaneous firing rate of MCG neurons as well as the neuronal membrane responsiveness to iontophoretically applied prolactin was unaffected by the presence or absence of ovarian hormones. In both treated and untreated rats, the majority of neurons were not responsive to prolactin. On the other hand, the responsiveness of MCG neurons to iontophoretically applied LH-RH was influenced by hormonal treatment. A significantly larger number of MCG neurons were inhibited by LH-RH in hormone-treated animals than in untreated rats. The present work provides evidence at the electrophysiological level that ovarian hormones do not affect the firing rate of MCG neurons but do modulate the responsiveness of MCG neurons to LH-RH.

Action Potentials↗
PubMed1985

Fiber number and type composition in extensor digitorum longus, soleus, and diaphragm muscles with aging in Fisher 344 rats.

Histochemical (M-ATPase) fiber typing was done on extensor digitorum longus, (EDL), soleus (SOL), and diaphragm (DIA) muscles of barrier-reared Fisher 344 rats obtained at four different ages (3, 9, 28, and 30 months) from the colonies of the National Institute of Aging. In the EDL there are no differences in the percent of type I fibers among the four age groups. The percent of type IIa and IIb fibers also showed no difference between the 3 and 30 month age groups. There was no apparent trend for an increase or decrease in the percent of type IIa or IIb fibers between the four age groups. In both the SOL and DIA muscles the percent of type I fibers was greater in the aged than in the young groups. The percent of type IIa fibers was lower in the 30 month group than in the younger groups for both muscles. The percent of type IIb (DIA) and IIc (SOL) fibers did not change between groups. Total fiber number per cross section of muscle showed no change in the EDL over this age range or in the SOL after 9 months of age. These findings bring into question published results that imply that decreasing fiber number and preferential loss of type II (a and b) fibers are typical aging phenomena.

Adenosine Triphosphatases↗
PubMed1985

Possible delta receptor mediation of the effect of beta-endorphin on luteinizing hormone (LH) release, but not on prolactin (PRL) release, in the ovariectomized rat.

Administration of opioid receptor antagonists was utilized to determine the opioid receptor type involved in the suppression of LH release by beta-endorphin (beta-END). Long-term (three to four weeks) ovariectomized rats with chronic third ventricular cannulae were fitted with jugular catheters and received treatment with vehicle or one of three opioid antagonists. The delta antagonist ICI 154, 129, but not the mu1 or mu antagonists naloxazone or beta-funaltrexamine, respectively, blocked the suppressive effect of beta-END on plasma LH levels and transiently but significantly increased LH levels above preinfusion value. None of the antagonists significantly reduced the beta-END-induced release of PRL. These results provide evidence that the inhibitory effect of beta-END on LH release may be mediated by delta receptors.

Animals↗
PubMed1985

Impact of computerization on dispensing time in an ambulatory-care pharmacy.

The effect of computerization on dispensing time in a hospital-affiliated ambulatory-care pharmacy was studied. Personnel time requirements for dispensing medications were measured by hospital systems-development personnel three months before and six months after implementation of computer-assisted dispensing. Times required for completion of all activities associated with dispensing new and refill medications were recorded. A varying number of random samples for each activity were timed on several different days in each dispensing system. The time recorded for each activity reflected time for completion of that activity for all of a patient's prescriptions. Based on mean times for each activity, prescription processing time per patient (average of 1.5 prescriptions) was 7.0 minutes for both new and refill prescriptions using manual dispensing, 6.28 minutes for new prescriptions using computer-assisted dispensing, and 4.61 minutes for refill prescriptions using computer-assisted dispensing. Computerization eliminated 78 minutes of time spent on miscellaneous activities each day and added 58.67 minutes of time for computer-related activities each day. A net time savings of 196.58 minutes was realized for a prescription volume of 176 prescriptions per day. Although implementation of computer-assisted dispensing involved economic costs and procedural changes, it increased the efficiency of this outpatient pharmacy operation.

Alabama↗
PubMed1984

Analytical isoelectric focusing using a high-voltage vertical slab polyacrylamide gel system.

A commercially supplied vertical slab electrophoresis system has been modified to permit electrofocusing of thin gels using electrical potentials of 3000 V and higher. Polyacrylamide gels (5.65% T, 2.65% C; 2.4-3.3% (w/v) ampholytes; 0.35 mm thick X 98-105 mm long X 140 mm wide) were run under native and denaturing conditions. Accurate temperature regulation and atmospheric control were obtained by casting the gel between two glass plates, and then completely submerging the gel in the lower tank buffer. As many as 18 samples were loaded into wells at the top of each gel. Protein standards and mouse ascites fluid were focused on gels in the native state using a broad-range blend of commercial ampholytes from pH 3.5 to 10. Narrow-range pH ampholyte blends were also used: pH 2.5 to 6 under denaturing conditions resolving bovine calmodulins; pH 4 to 6 under a native condition for human plasma proteins including immunoglobulin G, fibronectin, and fibrinogen; pH 4 to 6 under denaturing conditions for myosin light chains; pH 6 to 9 under native conditions for human hemoglobins; and pH 9 to 11 under denaturing conditions to separate 30 S ribosomal subunit proteins. High-voltage vertical slab electrofocusing provides a means for rapid resolution of multiple protein samples using stable pH gradients. The method is especially valuable in ranges near pH 2.5 and pH 10.5 in which difficulties have previously been encountered with regard to atmospheric control and temperature regulation using conventional focusing techniques.

Animals↗
PubMed1984

Dopaminergic neurons in the mediobasal hypothalamus of old rats: evidence for decreased affinity of tyrosine hydroxylase for substrate and cofactor.

The effect of aging on the activity of tyrosine hydroxylase (TH) and on the number of TH-positive perikarya in the hypothalamus was studied in old and young female rats. The activity of TH in the mediobasal hypothalamus (MBH) of old rats was significantly (P less than 0.025) less than that in young rats. In old rats, the Km of TH for tyrosine as well as cofactor, 6-methyl-5,6,7,8-tetrahydropterine (6MPH4), was markedly greater than the Km in young rats. The maximal velocity was only slightly reduced in old animals. Contiguous coronal sections of the brain of an old and a young female rat were immunocytochemically stained for TH, and the TH-positive perikarya in the hypothalamus were counted. In the circumventricular region, 6793 TH-positive perikarya were present in the young brain and 6632 in the old brain. In the arcuate region, 2868 and 2760 TH-positive perikarya were counted in the young and old brain, respectively. It is concluded that the reduced TH activity in the MBH of old rats is not a consequence of a reduction in the number of TH-positive perikarya in the arcuate or circumventricular regions of the hypothalamus but is due to a reduction in the affinity of TH for its substrate and cofactor.

Age Factors↗
PubMed1984

Beta-endorphin suppression of lordosis behavior in female rats; lack of effect of peripherally-administered naloxone.

Endogenous opioid peptides have been implicated in the control of copulatory behavior of the male rat. In order to assess the possible role of opioids in modulation of sexual receptivity in the female rat, lordosis behavior of ovariectomized (OVX) steroid-primed rats was tested after administration of beta-endorphin (B-END) or naloxone (NAL). Lordosis-to-mount ratio (L/M) of estrogen (E) - and progesterone (P) -primed rats was suppressed 15 and 45 minutes after intraventricular infusion of 100 ng B-END. This suppressive effect was blocked by subcutaneous injections of NAL (2 mg/kg). NAL alone, however, failed to enhance L/M in E-primed rats when administered in subcutaneous doses of 2 or 40 mg/kg. Thus, B-END is capable of suppressing lordotic responsiveness, but endogenous B-END does not appear to tonically suppress responsiveness in the E-primed rat.

Animals↗
PubMed1984

Site of action for beta-endorphin-induced changes in plasma luteinizing hormone and prolactin in the ovariectomized rat.

A number of sites have been hypothesized as loci at which opioid substances act to alter the secretion of luteinizing hormone (LH) and prolactin (PRL) (1-8). The aim of the present study was to determine the site(s) at which the opioid peptide beta-endorphin (beta-END) acts to influence plasma LH and PRL levels in the ovariectomized (OVX) rat. beta-END, administered into the third ventricle of conscious OVX rats fitted with jugular catheters, significantly decreased plasma LH in doses greater than or equal to 50 ng and increased PRL levels at all doses administered (10, 50, 100 and 250 ng) in a dose dependent fashion. To identify possible central nervous system sites of action, 250 ng beta-END was unilaterally infused into various brain sites. Plasma LH was significantly decreased and plasma PRL significantly increased by infusions into the ventromedial hypothalamic area, the anterior hypothalamic area, and the preoptic-septal area. There was no significant effect of beta-END infusions into the lateral hypothalamic area, amygdala, midbrain central gray, or caudate nucleus. When hemipituitaries of OVX rats were incubated in vitro with beta-END (10(-7)M to 10(-5)M), there was no suppression of basal or LHRH-induced LH release, nor was there any alteration of basal PRL release. It is concluded that beta-END acts at a medial hypothalamic and/or preoptic-septal site and not the pituitary, to alter secretion of LH and PRL.

Animals↗
PubMed1984

Lesions confined to the ventromedial hypothalamus decrease the frequency of coital contacts in female rats.

Ovariectomized female rats received either bilateral radiofrequency lesions of the ventromedial nucleus of the hypothalamus (VMH) or control treatments and were tested for copulatory activity following either estrogen (E) alone, or E plus progesterone (P) administration. In separate experiments the females were tested in two testing apparatuses both of which allowed the test females to control their contacts with sexually active males. One of the testing apparatuses also allowed the females to control their contacts with sexually inactive males and ovariectomized females. Females receiving VMH lesions engaged in fewer coital contacts with sexually active males than sham-operated females in the E plus P condition. Lesioned females also tended to spend less time with sexually active males than did sham operates in both the E and E plus P hormonal conditions. The VMH-lesioned females did not differ from the sham-operated females in the ability to display lordosis during the coital contacts or the frequency and duration of visits to the inactive males or ovariectomized females. The sham-operated females did have some transitory alterations in copulatory behavior in comparison to unoperated control females.

Animals↗
PubMed1984

p-Chlorophenylalanine alters pacing of copulation in female rats.

When tested in apparatus that allowed them to determine their contacts with conspecifics, including sexually active male rats, estrogen- and progesterone-treated female rats systemically treated with para-chlorophenylalanine (PCPA), a tryptophan hydroxylase inhibitor, showed reduced frequency of coital contacts and reduced duration of interactions with sexually active males. PCPA administration did not alter contacts with noncopulating males or other females nor did treated females differ from controls in ability to display lordosis or posing, both stereotyped behaviors characteristic of female rats in behavioral estrus. It is suggested that the alteration of temporal pacing of copulation in the PCPA-treated females is a result of drug-induced changes in the processing of exteroceptive stimuli.

Animals↗
PubMed1984

Contraction of rabbit skinned skeletal muscle fibers at low levels of magnesium adenosine triphosphate.

The contractile properties of skinned single fibers from rabbit psoas muscle were investigated under conditions of low MgATP and no Ca2+ (i.e., less than 10(-8) M). At 1 microM MgATP, fibers shortened at a maximum velocity of 660 +/- 420 A/half sarcomere/s (n = 9), compared with 34,000 A/half sarcomere/s measured during maximum Ca2+-activation at 1 mM MgATP (Moss, R. L., 1982. J. Muscle Res. Cell. Motil ., 3:295-311). The observed dependence of Vmax on pMgATP between 7.0 and 5.3 was similar to that of actomyosin ATPase measured previously by Weber, A., R. Herz , and I. Reiss (1969, Biochemistry, 8:2266-2270). Isometric tension was found to vary with pMgATP in a manner much like that reported by Reuben , J. P., P. W. Brandt, M. Berman , and H. Grundfest (J. Gen. Physiol. 1971. 57:385-407). A simple cross-bridge model was developed to simulate contractile behaviour at both high and low levels of MgATP. It was found that the pMgATP dependence of Vmax and ATPase could be successfully modeled if the rate of detachment of the cross-bridge was made proportional to the concentration of MgATP. In the model, the similar dependence of Vmax and ATPase on pMgATP was derived from the fact that in this range of pMgATP every pass of a cross-bridge by an actin site resulted in an attachment-detachment cycle, and every such cycle caused hydrolysis of one molecule of ATP.

Adenosine Triphosphatases↗
PubMed1984

Hormonal and chemical modulation of ventromedial hypothalamic neurons responsive to vaginocervical stimulation.

Neurons of the ventromedial hypothalamus (VMH) in female rats were electrophysiologically recorded via multibarrelled glass micropipettes and tested for responsiveness to vaginocervical stimulation as well as to a variety of other peripheral stimuli. A small percentage of VMH neurons were found to be specifically responsive to vaginocervical stimulation (type I response) in the ovariectomized animal. Priming the rats with estrogen (E) and progesterone (P) significantly increased the percentage of neurons responding specifically to vaginocervical stimulation but had no effect on the percentage of nonspecifically responding (type II) and nonresponding (type III) neurons. Pharmacological testing of all three types of VMH neurons was accomplished by iontophoretic application of luteinizing hormone releasing hormone (LHRH), prolactin (PRL), and dopamine (DA) to the cell membrane. PRL excited the majority of neurons tested and DA inhibited the majority of tested units regardless of the hormonal condition of the animal or the response elicited by vaginocervical and peripheral stimulation, LHRH, however, produced changes in firing rate which were related to the type of response evoked by vaginocervical stimulation. In E-P-primed animals, neurons which were specifically or nonspecifically affected by vaginocervical stimulation responded to LHRH in a similar manner whereas a different LHRH response profile was obtained in those neurons which were not effected by vaginocervical stimulation. The results indicate that an afferent pathway from the vaginocervix to the VMH exists, that E-P priming in some manner increases the probability that a VMH neuron will respond specifically to vaginocervical probing, and that the effect of LHRH is different in neurons responding to vaginocervical stimulation than in nonresponding neurons.

Animals↗
PubMed1983

Differential effects of morphine, dopamine and prolactin administered iontophoretically on arcuate-ventromedial hypothalamic neurons.

The effect of iontophoretically applied morphine, dopamine and prolactin on the spontaneous, extracellular electrical activity of arcuate-ventromedial hypothalamic neurons was studied in urethane-anesthetized female rats. The deposition of morphine and dopamine suppressed, while prolactin was found to enhance, the rate of spontaneous firing of more than half of the neurons recorded. It is suggested that the present findings may be of significance in the understanding of the interaction of the opioids, dopamine, and prolactin in the regulation of prolactin secretion.

Animals↗
PubMed1983

Improved methodology for analysis and quantitation of proteins on one-dimensional silver-stained slab gels.

A sodium dodecyl sulfate-discontinuous polyacrylamide gel electrophoresis system for separation and quantitation of low-molecular-weight (75 to 10K Da) proteins from single muscle fibers is described. Slab gels (0.75 mm thick) were stained using an improved silver-stain technique which does not require photographic fixers in order to achieve low-level background staining. The modified staining procedure uses continuous flow washing to minimize the handling of gels. The procedure has high sensitivity and gave a linear response between approximately 2 and 70 ng of protein per band. In addition, a convenient method for mounting slab gels for photography, scanning, and long-term storage has been developed.

Animals↗
PubMed1983

Construction of a simple spike counter for analysis of electrophysiological recording data.

A method for constructing a simple spike counter from a conventional calculator by taking advantage of the "adding display to memory" function [(M+) key] is described. The modification involves connecting the (M+) key to a dissecting pin and to a metallic notebook binder which is taped on to a transparent plastic sheet. The plastic sheet can then be placed on top of a polygraph record. After entering "1" into the calculator, a spike can be counted by making a single contact between the pin and the metal fastener. The total number of spikes counted can be displayed on the calculator by pressing the key for memory recall. The spike counter described herein is suitable for counting extracellular action potentials recorded on chart paper as well as other biological signals such as the rate of contraction of muscle.

Animals↗
PubMed1983

Midbrain LHRH infusions enhance lordotic behavior in ovariectomized estrogen-primed rats independently of a hypothalamic responsiveness to LHRH.

Lordotic behavior of ovariectomized estrone-primed rats was measured after infusions of luteinizing hormone-releasing hormone (LHRH), thyrotropin (TRH) or saline into the ventrolateral midbrain central gray (VL-MCG), or after LHRH or saline infusions into a lateral control site, the dorsolateral reticular formation (DL-RF). Infusion of LHRH, but not TRH, into the VL-MCG increased lordotic behavior. LHRH had no effect in the DL-RF. In a second experiment, rats were fitted with cannulae in the VL-MCG and in the arcuate-ventromedial nucleus area (ARC-VM). Serotonin was infused into the ARC-VM, and LHRH was infused into either the ARC-VM or the VL-MCG. Serotonin blocked the behavioral effect of LHRH infusion into the ARC-VM, but did not prevent enhancement of lordosis by LHRH infusions into the VL-MCG. These results suggest that LHRH infusions into the midbrain do not require hypothalamic responsiveness to LHRH for their effect, and are therefore unlikely to act by diffusion of LHRH rostrally. The effect of LHRH in the midbrain is site-specific, since lateral infusions (1.75 mm away) were ineffective.

Animals↗
PubMed1983

Effects of lesions of putative LHRH-containing pathways and midbrain nuclei on lordotic behavior and luteinizing hormone release in ovariectomized rats.

Lordotic behavior and LH release were measured in ovariectomized rats after radiofrequency lesions of the midbrain central gray (MCG), interpeduncular nucleus (IPN), mammillary bodies (MMM), stria medullaris (SM), or fasciculus retroflexus (FR), areas which are reported to contain immunoactive luteinizing hormone-releasing hormone (LHRH), a hypothalamic decapeptide which has been implicated in the neuroendocrine control of lordosis. SM and FR lesions increased lordotic behavior after estrone-priming. IPN lesions reversed an increase in lordotic behavior seen in IPN sham-lesioned animals treated with estrone. MCG lesions decreased lordotic behavior after estrone-priming, while MMM lesions had no effect. None of the lesions significantly altered lordotic responsiveness when animals were repeatedly mated or were treated with estrone + progesterone. There was a slight decrease in serum LH levels in SM animals. Results are interpreted in terms of the role of LHRH in control of lordosis, and of midbrain mechanisms for influencing lordotic behavior.

Animals↗