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PubMed1991

Characterization of receptors mediating the actions of dopamine on an identified inhibitory motoneurone of the cockroach.

1. The effects of a number of dopaminergic agonists and antagonists upon the soma of a prothoracic inhibitory motoneurone of the cockroach (Periplaneta americana) have been recorded under voltage-clamp conditions. 2. Dopamine generates inward currents that are extremely voltage-dependent: currents increase rapidly at membrane potentials more negative than about -120 to -150 mV and also show a peak at membrane potentials of approximately -20 mV. As a result of this voltage-dependence, dopamine induces a region of negative resistance in the current-voltage relationship of the neurone. 3. The dopaminergic agonists apomorphine, bromocriptine, ergometrine and A-6,7-DTN mimic the action of dopamine on this neurone, all having a similar voltage-dependence to that of dopamine. The selective D-1 receptor agonist SK&F82526 and the D-2 agonist LY 171555, however, were both inactive on the preparation. 4. Responses to dopamine were suppressed by a number of D-1 and D-2 receptor antagonists, indicating that the pharmacological profile of the dopamine-sensitive receptor in this insect preparation is different from that of vertebrate dopamine receptors.

Animals↗
PubMed1999

High-frequency steering maneuvers mediated by tactile cues: antennal wall-following in the cockroach.

Cockroaches (Periplaneta americana) use their antennae to detect a wall and to maintain a constant distance from it as they walk or run along it. The faster they run, the closer they position themselves to the wall. They also use their antennae to detect and follow multiple accordion-like projections in the wall. They can make up to 25 body turns s-1 for short periods during rapid running to follow such wall projections. Each turn apparently involves a change in stepping direction. These turns help to avoid collisions with the outward projections, while keeping the body close to the wall. Sensory inputs from the flagellum of the antenna, and not from its base, appear to evoke the turns in response to wall projections. These flagellar inputs appear to report the position along the antenna of its contact with the wall and/or the position of the consequent antennal bend. This flagellar information constitutes a one-dimensional sensory map, with location along the map indicating the distance to the wall.

Animals↗
PubMed1975

Regeneration of peripheral nerves to supernumerary legs in cockroaches.

1. Clusters of legs were grown from metathoracic coxae of the cockroach. Legs of a cluster had different segmental origins, sizes, and orientations. 2. Regenerating metathoracic nerves tended to enter the nearest leg, and to a lesser extent of the largest leg, but showed no significant tendency to penetrate metathoracic rather than prothoracic legs, or normally oriented rather than abnormally oriented legs. 3. Movements of legs were evoked by nerve stimulation significantly more often in nearest, largest, and normally oriented legs, but were equally frequent in prothoracic and metathoracic legs. 4. Close proximity of peripheral nerves is not required for the differentiation of the legs, since nerves were visible in the legs only at the later stages of their development, and many of the legs were apparently nerve innervated.

Animals↗
PubMed1976

Properties of the trochanteral hair plate and its function in the control of walking in the cockroach.

1. The physiological properties of the group of long hair sensilla of the trochanteral hair plate in the cockroach metathoracic leg were studied. The sensilla were divided into type I and type II according to their responses to imposed displacements. 2. Type I hair sensilla responded to dynamic displacements whereas type II hair sensilla responded to both dynamic and static displacements. The hair sensilla are normally excited by phasic flexion movements of the femur near the end of leg protraction. 3. Activity in the trochanteral hair plate afferents had a short latency excitatory effect on the motoneurone producing slow extension movements of the femur and an inhibitory effect on the femur flexor motoneurones. 4. Removal of the trochanteral hair plate in one leg caused overstepping of that leg in a walking animal due to exaggerated flexion of the femur. This change in leg movement can be explained by the removal of the inhibitory influence from the hair plate afferents to the femur flexor motoneurones. 5. We conclude that one function of the trochanteral hair plate is to limit femur flexion during a step cycle.

Action Potentials↗
PubMed1976

Connexions between hair-plate afferents and motoneurones in the cockroach leg.

1. The trochanteral hair-plate afferents in the metathoracic leg of the cockroach, Periplaneta americana, were stimulated electrically and at the same time intracellular recordings were made from either motoneurones, interneurones or afferent terminals within the methathoracic ganglion. 2. Activity in the hair-plate afferents evoked short latency excitatory postsynaptic potentials (EPSPs) in femur flexor motoneurones. The latency of the IPSPs was on average 1-8 ms longer than the latency ofthe EPSPs. 3. Intracellular recordings from terminal branches of the hair-plate afferents showed that the delay between the peak of the afferent terminal spike and the beginning of the EPSPs is about 0.4 ms. This finding, together with the observations that the amplitude of the EPSPs is increased by the passage of hyperpolarizing current and decreased following high-frequency stimulation, indicates that the EPpSPs are evoked via-monosynaptic chemical synaptic junctions. 4. The observations of the long latency of the IPSPs, the need for a number of afferents to be simultaneously acive for them to be evoked and the occasional variability in latency, all indicate that the IPSPs are evoked via a disynaptic pathway...

Action Potentials↗
PubMed1976

The actions of some putative neurotransmitters on the cockroach salivary gland.

1. Certain putative transmitters were applied to the innervated cockroach salivary gland and their effects on the resting potential and the neurally evoked secretory potential of the acinar cells were observed. 2. gamma-Aminobutyric acid, glutamate, glycine, aspartate and alanine had no significant effect on the resting potential. However, gamma-aminobutyric acid and glutamate reduced the neurally evoked secretory potential but only at concentrations above 10(-3) M3. Acetylcholine and carbachol appeared to act by modifying transmitter output from the salivary nerves. These substances failed to have any effect on the resting potential. 4. The biogenic amines, adrenaline, dopamine, noradrenaline, 5-hydroxy-tryptamine and octopamine, produced hyperpolarizing responses, graded according to concentration. 5. It is suggested that dopamine, the most potent of the biogenic amines tested, is the transmitter at this junction.

Acetylcholine↗
PubMed1980

The statistical analysis of spontaneous transmitter release at individual junctions on cockroach muscle.

1. Miniature excitatory post-synaptic potentials (MEPSPs) were recorded extra- and intracellularly from the coxal depressor muscle of the cockroach, Periplaneta americana. 2. Statistical analysis of the time intervals between MEPSPs showed that the variance-to-mean curve for the extracellular data sets lay significantly above the line predicted for a Poisson process. A shuffling procedure, however, made the series almost random. 3. The serial correlation coefficients for the extracellular data sets exceeded the confidence limits for various lags and most of them were positive. In comparison with the intensity function, the departure from the random process appeared to be mainly due to large positive correlation of intervals. 4. It is concluded that in insect neuromuscular junctions, the spontaneous release of transmitter at individual sites is more clustered than that predicted by a Poisson process.

Acetylcholine↗
PubMed1982

The effects of axotomy upon the extrasynaptic acetylcholine sensitivity of an identified motoneurone in the cockroach Periplaneta americana.

The effects of axotomy on the sensitivity of the fast coxal depressor motoneurone (Df) of the cockroach (Periplaneta americana) to applied acetylcholine (ACh) and carbamylcholine (CCh) have been investigated. ACh and CCh applied to the soma membrane either by bath perfusion or by ionophoresis caused depolarization; repeated application of large doses of these agonists resulted in a relatively rapid desensitization and depression of the response. Axotomy performed 3-10 days before recordings were made caused an approximately threefold increase in the sensitivity to ACh but had no affect upon the sensitivity to CCh. The resting potential, input resistance and membrane time-constant remained within the normal range. In addition there was no change in the rise-times of the responses or of the ACh reversal potential, or in the apparent number of ACh molecules needed to combine with individual cholinoceptors to produce a response. The anticholinesterases physostigmine and neostigmine potentiated the ACh response at relatively low concentrations (10(-7) M-10(-6) M). This potentiation was significantly greater in the normal cells than in the axotomized cells. It is therefore concluded that the increase in ACh sensitivity of this motoneurone results at least partly from a fall in the activity of cholinesterase in the region of the applied drug.

Acetylcholine↗
PubMed2002

Asthma in the elderly: cockroach sensitization and severity of airway obstruction in elderly nonsmokers.

STUDY OBJECTIVES: To test the hypothesis that the presence of sensitization to indoor allergens is associated with increased severity of airway obstruction in elderly subjects with asthma. DESIGN: Cohort study of subjects enrolled in a public hospital asthma clinic. SETTING: Asthma clinic in a municipal public hospital serving an indigent population in New York City. PATIENTS: Subjects aged > or = 60 years with asthma who were enrolled in the Bellevue Hospital Asthma Clinic. Total serum IgE and allergen-specific IgE measurements were performed in a cohort of elderly never-smokers who had asthma (45 patients) who had undergone spirometry before and after bronchodilator (BD) therapy. MEASUREMENTS AND RESULTS: The results of radioallergosorbent tests demonstrated that most subjects (ie, 60%) were sensitized to at least one allergen, with many sensitized to at least one indoor allergen. Cockroach (CR) was the most common allergen to which subjects were sensitized, with 47% displaying an elevated serum-specific IgE level. Fewer subjects were sensitized to dust mite, cat, dog, or ragweed. Subjects sensitized to CR (CR+) had greater reductions in airflow compared to subjects not sensitized to CR (CR-) [64 +/- 4.4% predicted vs 77.1 +/- 4.1% predicted FEV(1), respectively; p < 0.05]. Following BD administration, only 29% of CR+ subjects achieved a normal post-BD FEV(1) compared to 58% of CR- subjects. Lung volume measurements differed between CR+ and CR- subjects, with a greater elevation of functional residual capacity in CR+ subjects. CONCLUSION: In a population of elderly urban patients with asthma, the presence of CR-specific serum IgE is associated with more severe asthma, as reflected by an increase in airway obstruction and hyperinflation.

Aged↗
PubMedDate not supplied

Metabolic transformation of the brassinosteroid 24-epi-castasterone by the cockroach Periplaneta americana.

After feeding of 24-epi-castasterone to the cockroach Periplaneta americana an organ-specific epimerization of the brassinosteroid to 2,24-diepi-castasterone could be detected in female insects. The metabolite being observed only in the ovaries and not in the testes of the insect was identified by GC/MS in comparison with a synthesized authentic sample. Contrary, 24-epi-brassinolide is not metabolized in the sexual organs of Periplaneta americana. This is the first evidence of a metabolic transformation of a brassinosteroid in insects.

Animals↗
PubMed2004

Estradiol-stimulated nitric oxide release in nervous tissue, vasculature, and gonads of the giant cockroach Blaberus craniifer.

The vertebrate system of steroid hormones appears to have been conserved widely throughout the animal kingdom. The sex hormone estrogen, 17-beta-estradiol (E2), long considered to be exclusively a vertebrate hormone, is found also in invertebrates related to reproductive and developmental processes such as spawning, vitellogenesis and molting. These processes are affected by estrogen induced changes at the genomic level and take place at a large time scale. The discovery of surface membrane receptors for E2 has opened new possibilities for the involvement of estrogen in biological functions other than reproductive. These processes take place within a few seconds to minutes and involve sudden cytosolic calcium transients, activation of adenylate cyclase or activation of phospholipase C (PLC). E2 can modulate the production of nitric oxide (NO) in endotheliar and other cells. A similar mechanism linking estrogen to cNOS catalized nitric oxide (NO) release is reported herein for the first time in several tissues of the giant cockroach Blaberus craniifer. This process has been identified in the brain, nerve cord, vasculature and ovaries. This effect is concentration dependent and is inhibited by tamoxifen an estrogen receptor blocker.

Animals↗
PubMed2002

Efficacy of oral sulfadimethoxine against two gregarine parasites, Protomagalhaensia granulosae and Gregarina cubensis (Apicomplexa: Eugregarinida), infecting the Death's Head cockroach, Blaberus discoidalis.

Gregarines are common parasites of insects in culture, but no effective chemotherapeutic or prophylactic control protocol has been demonstrated. Sulfadimethoxine was administered in 5- and 7-day treatments to Death's Head cockroaches (Blaberus discoidalis) infected with Gregarina cubensis and Protomagalhaensia granulosae to test the efficacy of this sulfonamide against gregarine infection. Sulfadimethoxine significantly reduced the mean intensity of both G. cubensis and P. granulosae. Sulfadimethoxine treatment reduced gregarine intensity by 80% to 85% but had no significant effect on gametocyst production, suggesting that sulfonamide toxicity is directed primarily at sporozoites, trophozoites, and perhaps young gamonts. The possible use of sulfadimethoxine to produce gregarine-free insect cultures and the potential utility of gregarines as target organisms for screening pharmacologically active compounds for use against other intestinal apicomplexans are discussed.

Animals↗
PubMed2004

Intracellular responses of antennal chordotonal sensilla of the American cockroach.

The responses of mechanoreceptor neurons in the antennal chordotonal organ have been examined in cockroaches by intracellular recording methods. The chordotonal organ was mechanically stimulated by sinusoidal movement of the flagellum. Stimulus frequencies were varied between 0.5 and 150 Hz. Receptor neurons responded with spike discharges to mechanical stimulation, and were classed into two groups from plots of their average spike frequencies against stimulus frequency. Neurons in one group responded to stimulation over a wide frequency range (from 0.5 to 150 Hz), whereas those in a second group were tuned to higher frequency stimuli. The peak stimulus frequency at which receptor neurons showed maximum responses differed from cell to cell. Some had a peak response at a stimulus frequency given in the present study (from 0.5 to 150 Hz), whereas others were assumed to have peak responses beyond the highest stimulus frequency examined. The timing for the initiation of spikes or of a burst of spikes plotted against each stimulus cycle revealed that spike generation was phase-locked in most cells. Some cells showed phase-independent discharges to stimulation at lower frequency, but increasing stimulus frequencies spike initiation began to assemble at a given phase of the stimulus cycle. The response patterns observed are discussed in relation to the primary process of mechanoreception of the chordotonal organ.

Action Potentials↗
PubMedDate not supplied

Sensitization to cockroach in Italy: a multicentric study.

The prevalence of sensitization to cockroach (CR) was evaluated by skin prick test (SPT) in 1299 patients consecutively referred for rhinitis and asthma to five allergy centers in northern, central, and southern Italy. In patients with positive SPT to CR, an SPT with D. pteronyssinus extract was made. RAST inhibition was performed with pooled sera of subjects with positive SPT and RAST of at least Class 3 for CR and D. Pteronyssinus, to assess the cross-reactivity between these two allergenic sources. The protein content of allergen extracts was assayed by isoelectric focusing (IEF). A total of 170 patients (13%) had a positive SPT with CR extract, and 133 of them (78.2%) were also positive for D. pteronyssinus. RAST inhibition showed a cross-reactivity between CR and D. pteronyssinus, and IEF detected in the extracts employed a series of bands focusing at the same pI of CR and D. pteronyssinus relevant allergens. Therefore, the prevalence of sensitization to CR in the population studied, corresponding to 13%, suggests that CR extract might be added to standard SPT panels for respiratory allergy. However, the cross-reactivity with D. pteronyssinus calls for careful evaluation of the clinical importance of this sensitization.

Adolescent↗
PubMed1996

The expression of locomotor circadian rhythm in female German cockroach, Blattella germanica (L.).

Fifteen percent of intact female German cockroaches (n = 13), Blattella germanica (L.) (Dictyoptera: Blattellidae), had weak free-running locomotor rhythmicity under 28 degrees C and constant darkness conditions. However, 86% of ovariectomized females (n = 14) showed a strong free-running rhythm under the same conditions with a circadian period of 23.60 +/- 0.15 h, similar to the male's period of 23.45 +/- 0.03 h. In addition, the locomotory activities occurred mainly during the subjective night under DD conditions as was the case in males. These results indicated that female locomotion was under the control of a circadian oscillator, which was masked by the existence of ovaries. This internal masking effect could be removed by the existence of males, but females had no effect on the locomotor pattern of another female. Since the male failed to entrain female locomotion, its role as a zeitgeber was excluded. That the locomotory pattern of the females still coincided with their reproductive cycle when exposed to male odor suggests that exposure to a male only partially removed the internal masking effects.

Animals↗
PubMed1990

Stimulation of carbohydrate metabolising enzymes by synthetic hypertrehalosemic peptides in thoracic musculature of the American cockroach, Periplaneta americana.

The ability of the synthetic hypertrehalosemic peptides, HT-I and HT-II, to influence the activities of glycogen phosphorylase, trehalase and hexokinase via elevation of Ca++ and cAMP levels was examined in thoracic musculature of the American cockroach, Periplaneta americana. The peptides effect dose- and time-dependent activation of phosphorylase, trehalase and hexokinase activities that occur concomitantly with elevated levels of intracellular calcium. In addition, HT-I increases the accumulation of cyclic AMP in muscle cells.

Amino Acid Sequence↗
PubMed2002

E- and P-selectins are essential for the development of cockroach allergen-induced airway responses.

Peribronchial inflammation contributes to the pathophysiology of allergic asthma. In many vascular beds, adhesive interactions between leukocytes and the endothelial surface initiate the recruitment of circulating cells. Previous studies using OVA-induced airway hyperreactivity indicated that P-selectin, a member of the selectin family expressed by activated platelets and endothelium, contributed to both inflammation and bronchoconstriction. The current study used cockroach allergen (CRA), an allergen that induces asthmatic responses in both humans and mice, to further investigate the role of selectins in the development of peribronchial inflammation and airway hyperreactivity. P- and E-selectin mRNAs were detected in extracts of CRA-sensitized animals beginning shortly after intratracheal challenge with CRA. The P-selectin mRNA was transiently induced at early time points while up-regulation of the E-selectin mRNA was more prolonged. Mice with targeted deletions in E-selectin (E(-)), P-selectin (P(-)), and both genes (E(-)/P(-)) showed 70-85% reductions in airway hyperreactivity, peribronchial inflammation, and eosinophil accumulation. The P(-) and E(-)/P(-) groups showed the most profound reductions. The transfer of splenic lymphocytes from CRA-primed E(-)/P(-) into naive wild-type (WT) mice produced the same level of airway hyperreactivity as transfers from CRA-primed WT into naive WT hosts, indicating that peripheral immunization was similar. The observed changes in the selectin-deficient animals were not related to inadequate sensitization, because CRA priming and challenge increased serum IgE levels. Furthermore, pulmonary Th2-type cytokines and chemokines in the E-selectin(-/-) and WT animals were similar. The findings indicate that both P- and E-selectin contribute to CRA-induced peribronchial inflammation and airway hyperreactivity.

Adoptive Transfer↗
PubMedDate not supplied

[Wing receptors of the American cockroach Periplaneta americana].

Wing receptors of the cockroach have been studied using staining technique with methylene blue in living animals. Five types of the receptors were found: trychoid hairs, bristles, complaniform sensillae, chordotonal organs and multiterminal neurons. The majority of the receptors is located at the lower surface of the wing, especially along its ribs. Together with primitive features in the structure (polyneuronal origin of hairs and bristles, poor content of chordotonal organs, absence of distinct groups of companiform sensillae), some specialization of wing receptors with respect to flight function is noted (concentration of proprioceptors along the main mechanical axis of the wing and formation of distinct rows by the companiform sensillae).

Animals↗