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H Penzlin

Publications and source records attributed to H Penzlin.

At least 19 recordsLinked to original sources
PubMed1998

Isolation of periviscerokinin-2 from the abdominal perisympathetic organs of the American cockroach, Periplaneta americana.

Using the isolated hyperneural muscle as bioassay, a novel myotropin was isolated from the abdominal perisympathetic organs of Periplaneta americana. This is the second neuropeptide identified from insect perisympathetic organs. Peptide sequence analysis and mass spectrometry yielded the following structure: Gly-Ser-Ser-Ser-Gly-Leu-Ile-Ser-Met-Pro-Arg-Val-NH2. This peptide, named periviscerokinin-2, was confirmed to be amidated by chemical synthesis, bioassay, and comparison of retention times between native and synthetic peptides. A highly specific antiserum was used to determine sites of synthesis in the abdominal ganglia. Besides periviscerokinin-1, periviscerokinin-2 is the only putative myotropic neurohormone from the abdominal perisympathetic organs that is effective in the nanomolar range. This confirms the hypothesis that the neurohormonal system of the ventral nerve cord is remarkably different from that of the brain.

Abdomen↗
PubMed1998

Species-specific action and distribution of tachykinin-related peptides in the foregut of the cockroaches Leucophaea maderae and Periplaneta americana.

Nine tachykinin-related peptides (TRPs) have been isolated from the brain and intestine of the cockroach Leucophaea maderae. In the present investigation, two of the nine TRPs, LemTRP 1 and 5, were tested for their ability to stimulate contractions in the foregut of the cockroaches L. maderae and Periplaneta americana in vitro. The two LemTRPs and the related locust peptide locustatachykinin I (LomTK I) induced contractions in the foregut of P. americana in a dose-dependent manner, but had no myostimulatory action in L. maderae. A half-maximal response for the LemTRPs and LomTK I was obtained at 5x10(-9)mol l-1. In both species, the neuropeptide proctolin stimulated foregut contractions. Using an antiserum to LomTK I, we demonstrated that in both species there are LomTK-like-immunoreactive (LomTK-LI) cell bodies and fibers within the ganglia and nerves of the stomatogastric nervous system. However, correlated with the species-specific action of the TRPs, we found efferent LomTK-LI nerve fibers supplying muscle fibers in the foregut of P. americana, but not in L. maderae. In both cockroach species, there is a rich supply of proctolin-immunoreactive fibers to the foregut muscle. Some of the LomTK-LI fibers supplying the P. americana foregut muscle contain co-localized proctolin immunoreactivity. These fibers appear to be derived from a large cell body in the frontal ganglion which also displayed co-localized immunoreactivities. Since TRP-containing neurons are restricted to the nerves and ganglia of the stomatogastric nervous system both in P. americana and L. maderae, TRPs may be involved in the control of foregut movements in both species, but in P. americana the control may be more complex with the additional peripherally projecting LomTK-LI neurons.

Animals↗
PubMed1998

omega-Toxins affect Na+ currents in neurosecretory insect neurons.

omega-toxins specifically block certain Ca2+ channels in mammalian neurons as well as in dorsal unpaired median neurons isolated from the cockroach Periplaneta americana. In these cockroach neurons both the P/Q-type blockers omega-agatoxin IVA and omega-conotoxin MVIIC but not the N-type Ca2+ channel blocker omega-conotoxin GVIA affected fast Na+ currents sensitive to tetrodotoxin and veratridine. Both omega-toxins enhanced Na+ current decay and thus decreased the amplitudes of the peak currents. They also led to a slower recovery from inactivation. Toxin effects developing within a few min were ot removed upon washing. They were not use-dependent. The description of the effect of omega-conotoxin MVIIC on current kinetics in terms of the Hodgkin-Huxley model revealed that steady-state parameters were not affected whereas the time constant of inactivation was considerably reduced. Under control conditions, the inactivation time constant is similar to the time constant of recovery from inactivation. The toxin-induced increase of the latter time constant and the decrease of the inactivation time constant indicate that inactivation can no longer be described by first-order kinetics.

Animals↗
PubMed1997

Isolation and structural elucidation of eight kinins from the retrocerebral complex of the American cockroach, Periplaneta americana.

By monitoring the contractile activity of the hindgut of the American cockroach in vitro eight myotropic neuropeptides were isolated from the retrocerebral complex of the American cockroach. Peptide sequence analysis and mass spectrometry yielded the following structures: Arg- Pro-Ser-Phe-Asn-Ser-Trp-Gly-NH2 (Pea-K-1), Asp-Ala-Ser-Phe-Ser-Ser-Trp-Gly-NH2 (Pea-K-2), Asp-Pro-Ser-Phe-Asn-Ser-Trp-Gly-NH2 (Pea-K-3), Gly-Ala-Gln-Phe-Ser-Ser-Trp-Gly-NH2 (Pea-K-4), Ser-Pro-Ala-Phe-Asn-Ser-Trp-Gly-NH2 (Pea-K-5), Asp-Pro-Ala-Phe-Ser-Ser-Trp-Gly-NH2 (Lem-K-7), Gly-Ala-Asp-Phe-Tyr-Ser-Trp-Gly-NH2 (Lem-K-8) and Ala-Phe-Ser-Ser-Trp-Gly-NH2 (Lom-K). The C-terminal sequence Phe-X-Ser-Trp-Gly-NH2 characterized the peptides as members of the insect kinin family. All structures were confirmed by comparison of retention times between synthetic and natural peptides. The threshold concentration for stimulatory effects of the synthetic peptides on the isolated hindgut was about 10(-9) M and there was no significant difference measured between the different kinin forms. These neuropeptides are the first members of the insect kinin-family isolated from the American cockroach. Their occurrence in the retrocerebral complex suggests a physiological role as neurohormone.

Amino Acid Sequence↗
PubMed1997

Isolation and structural elucidation of two pyrokinins from the retrocerebral complex of the American cockroach.

By monitoring the contractile activity of the hyperneural muscle of the American cockroach in vitro two peptides were isolated from the retrocerebral complex of the American cockroach. Three purification steps using reversed-phase high performance liquid chromatography on C-18 columns containing trifluoroacetic acid or heptafluorobutyric acid as organic modifiers were sufficient to achieve homogeneous peptide preparations. The structures of both peptides were elucidated by a combination of Edman degradation and mass spectrometry which yielded the following structures: His-Thr-Ala-Gly Phe-Ile-Pro-Arg-Leu-NH2 (Pea-PK-1) and Ser-Pro-Pro-Phe-Ala-Pro-Arg-Leu-NH2 (Pea-PK-2). The C-terminal sequence Phe-X-Pro-Arg-Leu-NH2 characterized the peptides as members of the insect pyrokinin family. The synthetic peptides were shown to have the same retention times as the natural peptides. The occurrence of both peptides in the retrocerebral complex suggests a physiological role as neurohormones. The effects of the synthetic pyrokinis were clearly distinguishable in their actions on the hyperneural muscle. Regarding the threshold concentrations, Pea-PK-2 was only 0.3% as active as Pea-PK-1.

Amino Acid Sequence↗
PubMed1997

Ca2+ currents in central insect neurons: electrophysiological and pharmacological properties.

Ca2+ currents in dorsal unpaired median (DUM) neurons isolated from the fifth abdominal ganglion of the cockroach Periplaneta americana were investigated with the whole cell patch-clamp technique. On the basis of kinetic and pharmacological properties, two different Ca2+ currents were separated in these cells: mid/low-voltage-activated (M-LVA) currents and high-voltage-activated (HVA) currents. M-LVA currents had an activation threshold of -50 mV and reached maximal peak values at -10 mV. They were sensitive to depolarized holding potentials and decayed very rapidly. The decay was largely Ca2+ dependent. M-LVA currents were effectively blocked by Cd2+ median inhibiting concentration (IC50 = 9 microM), but they also had a remarkable sensitivity to Ni2+ (IC50 = 19 microM). M-LVA currents were insensitive to vertebrate LVA channel blockers like flunarizine and amiloride. The currents were, however, potently blocked by omega-conotoxin MVIIC (1 microM) and omega-agatoxin IVA (50 nM). The blocking effects of omega-toxins developed fast (time constant tau = 15 s) and were fully reversible after wash. HVA currents activated positive to -30 mV and showed maximal peak currents at + 10 mV. They were resistant to depolarized holding potentials up to -50 mV and decayed in a less pronounced manner than M-LVA currents. HVA currents were potently blocked by Cd2+ (IC50 = 5 microM) but less affected by Ni2+ (IC50 = 40 microM). These currents were reduced by phenylalkylamines like verapamil (10 microM) and benzothiazepines like diltiazem (10 microM), but they were insensitive to dihydropyridines like nifedipine (10 microM) and BAY K 8644 (10 microM). Furthermore, HVA currents were sensitive to omega-conotoxin GVIA (1 microM). The toxin-induced reduction of currents appeared slowly (tau approximately 120 s) and the recovery after wash was incomplete in most cases. The dihydropyridine insensitivity of the phenylalkylamine-sensitive HVA currents is a property the cockroach DUM cells share with other invertebrate neurons. Compared with Ca2+ currents in vertebrates, the DUM neuron current differ considerably from the presently known types. Although there are some similarities concerning kinetics, the pharmacological profile of the cockroach Ca2+ currents especially is very different from profiles already described for vertebrate currents.

Animals↗
PubMed1995

Anatomy of neurons crossing the tritocerebral commissures of the cockroach Periplaneta americana (Blattaria).

The neuronal connections of the tritocerebral commissures of Periplaneta americana were studied in the brain-suboesophageal ganglion complex and the stomatogastric nervous system by means of heavy metal iontophoresis through cut nerve ends followed by silver intensification. The tritocerebral commissure 1 (Tc1) contains mainly the processes of the subpharyngeal nerve (Spn) whose neurons are located in both tritocerebral lobes and in the frontal ganglion. Some neurons of the frontal ganglion project through the Tc1 to the contralateral tritocerebrum. A few fibers in this commissure were observed projecting to the protocerebrum and the suboesophageal ganglion. There are tritocerebral neurons which pass through the Tc1 or the tritocerebral commissure 2 (Tc2) and extend on into the stomatogastric nervous system. One axon of a descending giant neuron appears in the Tc2. This neuron lies in the tritocerebrum and connects the brain to the contralateral side of the ventral nerve cord. In addition, sensory fibers of the labral nerve (Ln) traverse both commissures to the opposite tritocerebrum. The anatomical and physiological relevance of the identified neuronal pathways is discussed.

Animals↗
PubMed1995

Periviscerokinin (Pea-PVK): a novel myotropic neuropeptide from the perisympathetic organs of the American cockroach.

A myotropic neuropeptide was isolated from extracts of 1000 abdominal perisympathetic organs of males of the cockroach, Periplaneta americana. This peptide, termed periviscerokinin, has excitatory actions on the hyperneural muscle of Periplaneta americana. After peptide sequence analysis and mass spectrometry, the structure of this peptide was confirmed by chemical synthesis and bioassay to be Gly-Ala-Ser-Gly-Leu-Ile-Pro-Val-Met-Arg-Asn-NH2. This sequence is different from the other known myotropic peptides in insects. The threshold concentration for stimulatory effects of the synthetic peptide on the isolated hyperneural muscle was about 10(-9) M, suggesting a physiological role as a neurohormone.

Abdomen↗
PubMed1995

The role of proctolin in the antenna-heart beat acceleration of Periplaneta americana (L.).

So-called accessorial pulsatile circulatory organs in insects have developed during evolutionary reduction of the vascular system. As such a peripheral organ, the antenna-heart supplies the antennae with haemolymph. In the antenna-heart, the beat rhythm is generated by a myogenic automatism and is controlled neuronally. The electrical stimulation of the antenna-heart nerve produces an immediate heart beat inhibition brought about by octopamine release. Following this heart inhibition, an accelerating effect can be observed, which is based on a peptidergic mechanism. Proctolin-like material was found in both the dilator muscle and the antenna-heart nerve by means of immunocytochemistry. After HPLC-separation of antenna-heart tissue, proctolin was identified by sequencing the bioactive material and subsequent mass spectrometry. Proctolin proved to be extraordinarily effective producing stimulation of the antenna-heart beat rate up to 450%. The threshold concentration is 10(-10) mol.1(-1) and the value of the dissociation constant was fixed to KO = 1.3 x 10(-8) mol.1(-1). The chrono-trophic effect is caused by an increase in the steepness of the rising phase of pacemaker activity. The enhancement of the membrane resistance Rinput indicates a reduction of K(+)-conductance by proctolin. The PI-second messenger system is involved as well. Proctolin was identified and isolated from a real target organ. This fact and the physiological results furnished proof of peptidergic transmitter function of proctolin in the antenna-heart.

Animals↗
PubMed1994

Ca2+ currents in cockroach neurones: properties and modulation by neurohormone D.

In dorsal unpaired median (DUM) neurones isolated from the terminal ganglion of the cockroach Periplaneta americana two types of Ca2+ currents were found: a transient one activated by lower depolarizations (LVA) and a sustained one activated by higher voltage jumps (HVA). Both currents were strongly reduced by 100 microM Cd2+; Ni2+ was less effective. The HVA currents were insensitive to dihydropyridines, but sensitive to phenylalkylamines. The LVA component was sensitive to omega-conotoxin GVIA and SK&F96365 whereas the HVA component was insensitive to both blockers. The octapeptide neurohormone D (NHD), a member of the family of adipokinetic hormones (AKH-peptides), is known to increase the spiking frequence in these DUM cells. We demonstrate that NHD increases the LVA current component and decreases the HVA current component. These effects of NHD can explain the previously found NHD-induced stimulation of Ca2+ dependent K+ currents.

Animals↗
PubMed1994

Neurohormone D induces ionic current changes in cockroach central neurones.

The octapeptide neurohormone D (NHD), a member of the family of adipokinetic hormones (AKH-peptides), increases the frequency of spontaneous activity in dorsal unpaired median (DUM) neurones isolated from the terminal ganglion of the cockroach Periplaneta americana. The increase in spike frequency is accompanied by changes in the shape and the amplitude of the single action potentials, e.g. a more pronounced afterhyperpolarization. Effects of NHD on membrane currents were investigated in these DUM cells with whole-cell voltage-clamp measurements. A voltage-independent Ca2+ current flowing at the resting potential (ICa,R) was found. NHD, at nanomolar concentrations, enhanced this ICa,R in a concentration-dependent manner. 0.1 mM Cd2+ markedly reduced ICa,R and in this case ICa,R was hardly potentiated by NHD. In the presence of NHD a fast activating Ca(2+)-dependent K+ current sensitive to charybdotoxin and to low concentrations of tetraethylammonium was augmented. The enhanced afterhyperpolarization of action potentials can be accounted for by the increase in the Ca(2+)-dependent K+ current. The changes of the membrane currents induced by NHD are discussed with respect to further effects on the spike pattern and in relation to the previously described mode of action of AKH-peptides in other preparations.

Animals↗
PubMed1993

Taurine-like immunoreactivity in octopaminergic neurones of the cockroach, Periplaneta americana (L.).

Taurine (2-aminoethanesulphonic acid) is reported to interact with the octopaminergic system. The distribution of taurine-like immunoreactivity (-LIR) in relation to octopamine-like immunoreactive dorsal unpaired median (DUM) neurones was investigated with the aim of revealing possible colocalization of these two neuromediators. The specificity of the anti-taurine serum used was demonstrated by dot blot immunoassay and by use of preabsorption controls. There was no crossreactivity with octopamine. The specificity of the octopamine antiserum employed has been described elsewhere. Taurine-LIR could be demonstrated in large dorso-median cells in the suboesophageal and the mesothoracic ganglion as well as in the abdominal ganglia. In addition taurine-LIR is distributed in numerous other regions of the ganglia. A comparison of the immunostaining for taurine and octopamine indicates that several of the taurine-like immunoreactive (-LI) neurones are probably members of the octopamine-immunoreactive DUM cell population. These taurine-LI neurones resemble octopamine-LI DUM cells in soma position and size as well as in the projections of their primary neurites. Colocalization of octopamine-LIR and taurine-LIR within the same neuronal element could be shown by alternate immunostaining of consecutive sections. It is probable that all octopamine-LI DUM neurones also exhibit taurine-LIR, and the possible physiological significance of this coexistence is discussed.

Animals↗
PubMed1993

Stress-induced release of octopamine in the American cockroach Periplaneta americana L.

After stress, changes of octopamine content were observed in the antennal heart and the retrocerebral complex of cockroaches. Only individually handled animals exposed to short and extreme stress showed an alteration in the haemolymph octopamine levels. The removal of the retrocerebral complex resulted in an elevation of the octopamine content in the haemolymph. We suppose that the corpora cardiaca are not the only source for the octopamine released into haemolymph in stress situations.

Animals↗
PubMed1992

A new specific antibody reveals octopamine-like immunoreactivity in cockroach ventral nerve cord.

An antiserum was raised in rabbits immunized with octopamine conjugated to thyroglobulin. The specificity of this antiserum for octopamine is shown by dot blot immunoassay analysis. The antiserum does not crossreact with dopamine, noradrenaline, and serotonin, but slight crossreactivity with the amine tyramine at high concentrations was observed. The tyramine crossreactivity could be eliminated by preabsorption with a tyramine-glutaraldehyde-BSA conjugate. Using this antiserum, we describe the topographical distribution of octopamine-immunoreactive (ir) neuronal elements in wholemounts and paraffin sections of the ventral nerve cord of the American cockroach. The pattern of octopamine immunostaining is completely different from that obtained with an antidopamine serum, and can be blocked by preabsorbing the antioctopamine serum with BSA-conjugated octopamine. Cell bodies and dendritic processes of putatively octopaminergic dorsal (DUM) and ventral (VUM) unpaired median neurons were clearly octopamine-ir in all ganglia examined. The numbers of stained DUM somata in the mesothoracic, metathoracic, and terminal ganglion of females correspond to those of peripherally projecting DUM cells revealed previously by retrograde tracing (Gregory, Philos Trans R Soc Lond [Biol] 306:191, 1984; Tanaka and Washio, Comp Biochem Physiol 91A:37, 1988; Stoya et al., Zool Jb Physiol 93:75, 1989). In addition, various, previously unknown, paired cells with octopamine-like immunoreactivity were found in all ventral ganglia except abdominal ganglia 3-6. Some of these probably project intersegmentally.

Animals↗
PubMed1992

The octopaminergic system within the ventral nerve cord of the American cockroach.

Octopamine-immunoreactive neurons within the ventral nerve cord of the cockroach, Periplaneta americana, were mapped with a new anti-octopamine serum. The specificity of this antiserum was demonstrated by dot blot immunoassay and by comparing the immunocytochemical staining patterns obtained after incubation with anti-dopamine and anti-octopamine serum. Putative octopaminergic dorsal and ventral unpaired median (DUM resp. VUM) neurons showed octopamine-like immunoreactivity in all ventral ganglia. The numbers of DUM cells in the mesothoracic, metathoracic and terminal ganglia of females correspond to those previously characterized by retrograde staining 19, 33, 34. It could be shown that besides segmentally projecting there are also intersegmentally projecting DUM neurons within the thoracic ganglia. In addition various, previously unknown, paired octopamine-ir cells were revealed in all ventral ganglia except the abdominal ganglia 2-5.

Animals↗
PubMed1992

Function and modulation of the antennal heart of Periplaneta americana (L.).

The antennal heart of Periplaneta americana, a small accessory circulatory pump in the head, shows a rhythmicity with myogenic automatism. The muscle fibres extending throughout of the dilator muscle are electrically coupled. Among the peptides, proctolin causes a dose-dependent strong excitation, but allatostatin does not affect heart rhythm. However, allatostatin applied before proctolin antagonized the proctolin effect. In contrast to this, an immediate heart block produced by octopamine is similar to that produced by electrical stimulation of the nervus cardioantennalis. This inhibition is caused by a K(+)-dependent hyperpolarization. The second effect of octopamine is a delayed increase of the cAMP level. Because octopamine is present at the antennal heart, a physiological role is assumed.

Action Potentials↗
PubMed1990

Structure-function studies on neurohormone D: activity of naturally-occurring hormone analogues.

The relative potencies of 11 naturally-occurring peptides of the adipokinetic hormone/red pigment-concentrating hormone family (AKH/RPCH-family) have been assessed with respect to increase in heart rate in adult, female American cockroaches, Periplaneta americana, in in vitro and in vivo bioassays. In addition, analogues that lacked the N-terminal pyroglutamate residue or had a free threonine acid at the C-terminus were also investigated. In both bioassays the N- or C-terminal-modified analogues give no or little response suggesting that blocked termini are essential for receptor-binding. In both bioassays the naturally-occurring peptide from the cockroach corpus cardiacum Pea-CAH-I (neurohormone D) is more potent than the second endogenous peptide, Pea-CAH-II. On the basis of this result and previous data it is proposed that neurohormone D is the only physiologically important "true" cardioactive peptide. The dose-response curves of the other peptides indicate that in octapeptides, amino acid residues at positions 2, 6, and 7 are important for receptor-recognition, and that decapeptides are not as effective as octapeptides (exception: the peptide Rom-CC-I isolated from the grasshopper Romalea microptera).

Amino Acid Sequence↗