Serotonin and beyond-a tribute to Manfred Göthert (1939-2019).

Manfred Göthert, who had served Naunyn-Schmiedeberg's Arch Pharmacol as Managing Editor from 1998 to 2005, deceased in June 2019. His scientific oeuvre encompasses more than 20 types of presynaptic receptors, mostly on serotoninergic and noradrenergic neurones. He was the first to identify presynaptic receptors for somatostatin and ACTH and described many presynaptic receptors, known from animal preparations, also in human tissue. In particular, he elucidated the pharmacology of presynaptic 5-HT receptors. A second field of interest included ligand-gated and voltage-dependent channels. The negative allosteric effect of anesthetics at peripheral nACh receptors is relevant for the peripheral clinical effects of these drugs and modified the Meyer-Overton hypothesis. The negative allosteric effect of ethanol at NMDA receptors in human brain tissue occurred at concentrations found in the range of clinical ethanol intoxication. Moreover, the inhibitory effect of gabapentinoids on P/Q Ca2+ channels and the subsequent decrease in AMPA-induced noradrenaline release may contribute to their clinical effect. Another ligand-gated ion channel, the 5-HT3 receptor, attracted the interest of Manfred Göthert from the whole animal via isolated preparations down to the cellular level. He contributed to that molecular study in which 5-HT3 receptor subtypes were disclosed. Finally, he found altered pharmacological properties of 5-HT receptor variants like the Arg219Leu 5-HT1A receptor (which was also shown to be associated with major depression) and the Phe124Cys 5-HT1B receptor (which may be related to sumatriptan-induced vasospasm). Manfred Göthert was a brilliant scientist and his papers have a major impact on today's pharmacology.

17 Beta-estradiol regulates nNOS and eNOS activity in the hippocampus.

Estrogen treatment in symptomatic postmenopausal women appears to improve cognitive performance including memory, an effect which may involve enhanced nitric oxide formation in hippocampal neurons. To study whether 17beta-estradiol (E2) affects NO synthase activity in the hippocampus, we investigated the influence of E2 on hippocampal NO synthase expression and activity in female rats. Ovariectomy, which significantly decreased E2 serum levels, reduced neuronal (nNOS) and endothelial NO synthase (eNOS) expression and Ca(2+)-dependent NOS activity. E2 substitution reversed these effects. It is concluded that E2 increases nNOS and eNOS expression and activity in female hippocampus and thus improves hippocampal function.

Effects of cytoskeletal modifications on Ca2+ influx after cerebral ischemia.

The fungal toxin cytochalasin D as well as endogenous gelsolin depolymerize filamentous actin which may induce dynamic uncoupling of membrane ion channels. In vitro application of cytochalasin D reduced NMDA-induced [(3)H]noradrenaline release from mouse brain neocortical slices by 38%. In gsn deficient neocortical synaptosomes [Ca(2+)](i) increase in response to K(+) (30 mM) depolarization was 33% higher than in wild-type. After transient focal cerebral ischemia K(+)-induced [Ca(2+)](i) increase in neocortical synaptosomes was 56% lower than in synaptosomes prepared from the non-ischemic contralateral hemisphere. After in vivo pretreatment with cytochalasin D 10 min before MCA occlusion K(+)-induced [Ca(2+)](i) increase in synaptosomes in vitro prepared 1 h after reperfusion from the ischemic hemisphere was only 25% lower than in contralateral synaptosomes, while cytochalasin D pretreatment in vivo did not reduce K(+)-induced [Ca(2+)](i) increase in vitro. Hence, presynaptic Ca(2+) influx and subsequently neuronal vulnerability are attenuated by increased and are aggravated by decreased F-actin depolymerization.

Minocycline inhibits caspase-1 and caspase-3 expression and delays mortality in a transgenic mouse model of Huntington disease.

Huntington disease is an autosomal dominant neurodegenerative disease with no effective treatment. Minocycline is a tetracycline derivative with proven safety. After ischemia, minocycline inhibits caspase-1 and inducible nitric oxide synthetase upregulation, and reduces infarction. As caspase-1 and nitric oxide seem to play a role in Huntington disease, we evaluated the therapeutic efficacy of minocycline in the R6/2 mouse model of Huntington disease. We report that minocycline delays disease progression, inhibits caspase-1 and caspase-3 mRNA upregulation, and decreases inducible nitric oxide synthetase activity. In addition, effective pharmacotherapy in R6/2 mice requires caspase-1 and caspase-3 inhibition. This is the first demonstration of caspase-1 and caspase-3 transcriptional regulation in a Huntington disease model.

Reduction of post-traumatic brain injury and free radical production by inhibition of the caspase-1 cascade.

Necrotic and apoptotic cell death both play a role mediating tissue injury following brain trauma. Caspase-1 (interleukin-1beta converting enzyme) is activated and oligonucleosomal DNA fragmentation is detected in traumatized brain tissue. Reduction of tissue injury and free radical production following brain trauma was achieved in a transgenic mouse expressing a dominant negative inhibitor of caspase-1 in the brain. Neuroprotection was also conferred by pharmacological inhibition of caspase-1 by intracerebroventricular administration of the selective inhibitor of caspase-1, acetyl-Tyr-Val-Ala-Asp-chloromethyl-ketone or the non-selective caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone. These results indicate that inhibition of caspase-1-like caspases reduces trauma-mediated brain tissue injury. In addition, we demonstrate an in vivo functional interaction between interleukin-1beta converting enyzme-like caspases and free radical production pathways, implicating free radical production as a downstream mediator of the caspase cell death cascade.

Treatment of accidental high dose intraventricular mezlocillin application by cerebrospinal fluid exchange.

An accidental high dose of intraventricular mezlocillin was given during antibiotic treatment for pneumonia in a patient admitted because of severe traumatic brain injury and occlusive hydrocephalus. Because of serial epileptic seizures not responsive to antiepileptic drug treatment, CSF exchange was performed. The CSF was drained through a ventricular catheter, while mock CSF was infused into the lumbar subarachnoid space. The patient soon recovered to her clinical status previous to intraventricular mezlocillin application. Side effects of CSF exchange were not seen. Under continued antiepileptic medication no more seizures occurred. It is concluded that high doses of intraventricular mezlocillin have proconvulsive effects. In this patient CSF exchange was a suitable means of preventing putatively permanent impairment of brain function caused by serial epileptic seizures due to intraventricular mezlocillin application.

Expression of a dominant negative mutant of interleukin-1 beta converting enzyme in transgenic mice prevents neuronal cell death induced by trophic factor withdrawal and ischemic brain injury.

To explore the role of the interleukin (IL)-1 beta converting enzyme (ICE) in neuronal apoptosis, we designed a mutant ICE gene (C285G) that acts as a dominant negative ICE inhibitor. Microinjection of the mutant ICE gene into embryonal chicken dorsal root ganglial neurons inhibits trophic factor withdrawal-induced apoptosis. Transgenic mice expressing the fused mutant ICE-lacZ gene under the control of the neuron specific enolase promoter appeared neurologically normal. These mice are deficient in processing pro-IL-1 beta, indicating that mutant ICEC285G blocks ICE function. Dorsal root ganglial neurons isolated from transgenic mice were resistant to trophic factor withdrawal-induced apoptosis. In addition, the neurons isolated from newborn ICE knockout mice are similarly resistant to trophic factor withdrawal-induced apoptosis. After permanent focal ischemia by middle cerebral artery occlusion, the mutant ICEC285G transgenic mice show significantly reduced brain injury as well as less behavioral deficits when compared to the wild-type controls. Since ICE is the only enzyme with IL-1 beta convertase activity in mice, our data indicates that the mutant ICEC285G inhibits ICE, and hence mature IL-1 beta production, and through this mechanism, at least in part, inhibits apoptosis. Our data suggest that genetic manipulation using ICE family dominant negative inhibitors can ameliorate the extent of ischemia-induced brain injury and preserve neurological function.