Alexander G. Karczmar

Actions of substance P on sympathetic neurons

Abstract When applied to the neurons of isolated inferior mesenteric ganglia of guinea pig, substance P consistently caused a membrane depolarization accompanied, in many instances, by intense neuronal discharges. The substance P-induced depolarization or spikings were not abolished by d-tubocurarine and/or atropine or by superfusing the ganglia with a low Ca/high Mg solution. Repetitive stimulation of hypogastric nerves elicited a slow non-chol inergic depolarization which exhibited electrophysiological and pharmacological properties similar to those of substance P-induced depolarization. When ganglion cells were desensitized by continuous application of substance P, preganglionic stimulation failed to induce the slow non-cholinergic depolarization. These results suggest the possibility that the slow non-cholinergic depolarization may be due to the synaptic release of substance P.

Acute and long lasting central actions of organophosphorus agents

Abstract This review concerns aspects of anticholinesterase (anti-ChE) research that differ from those of the classical studies of these agents; to clarify the focus of this review, let me first allude to three classical aspects of anti-ChE research. Animal research as well as records of purposeful or accidental administration of anti-ChEs of both organophosphorus (OP) or carbamate and related types were initiated more than 100 years ago (see Holmstedt, 1959 , 1963 ; Koelle and Gilman, 1949 ; Karczmar, 1970a ). Initially, peripheral, particularly neuromyal effects of these drugs were studied in depth, whereas their central actions that were described included essentially only their toxic effects, i.e., respiratory depression and convulsions ( cf. Gilman, 1946 ; Krop and Kunkel, 1954 ). Behavioral and functional central actions of OP and carbamate drugs, while sporadically reported in the Thirties and Forties came into their own much later ( Sjostrand, 1937 ; Izergina, 1949 ; cf. Karczmar, 1970b ). The second characteristic aspect of the early studies of anti-ChEs is as follows: in conjunction with the discoveries of the Twenties through Forties concerning ChEs, acetylcholine (ACh) and cholinergic transmission and with the discovery of the action of physostigmine ( Stedman et al. , 1932 ) and OP drugs (see Bodansky, 1945 ) on ChEs it was felt that pharmacological effects of these drugs are due solely to ChE, particularly AChE, inhibition. Only in the Forties evidence militating against this concept was presented. The third classical concept, actually a corollary of the notion that OP and carbamate drugs act via their inhibition of ChEs, is that their action is short-lived or relatively short-lived as it depends on dissociation of the ChE-carbamate complex in the case of physostigmine and related drugs or on regeneration of ChEs in that of OP drugs, a process that may take at most days, or hours ( Srinivasan et al. , 1976 ). More recent studies suggest that it may be not so. Accordingly, this paper is intended as a brief summary of research concerning these three novel aspects of action of anti-ChEs: their central including behavioral and mental health effects; their actions that may not depend on ChE inhibition—which is also the subject of other papers of this issue; and, finally, their chronic and delayed actions.

Brain catecholamines and serotonin levels in various strains and genera of mice and a possible interpretation for the correlations of amine levels with electroshock latency and behavior

Abstract In a group of six genera and three strains of mice, widely differing in habitats and in behavioral profiles, the brain levels of DOPA, dopamine, norepinephrine, epinephrine, and serotonin were determined. Marked differences, up to three-fold, were found. Genera and strains with the highest levels of dopamine also had the highest levels of norepinephrine, epinephrine, and serotonin. Electroshock seizure latencies were well correlated with the biogenic amine levels; shorter latencies occurred in mice with low amine levels, longer latencies occurred in those with higher amine levels. A possible relationship between brain amines and certain behavioral characteristics of these genera is also discussed.

Effects of diisopropyl phosphorofluoridate on acetylcholine, cholinesterase and catecholamines of several parts of rabbit brain.

Abstract Diisopropyl phosphorofluoridate (DFP) was administered to rabbits in which the pretreatment with a monoamine oxidase inhibitor, JB835, and DOPA caused an elevation in nore-pinephrine (NE) and, to a lesser extent, in dopamine (DA) levels in the thalamus, hypothalamus, midbrain and hippocampus. Pretreatment with JB835-DOPA combination and/or elevation of NE and of DA caused no significant effect upon either cholinesterase activity or acetylcholine (ACh) levels in the caudate nucleus, midbrain, thalamus or hypothalamus. Diisopropyl phosphorofluoridate caused nearly complete inhibition of cholinesterase activity in all these brain parts whether or not the animals were pretreated with JB835 and DOPA, and with atropine. Diisopropyl phosphorofluoridate induced elevation of levels of ACh was somewhat lowered by JB835-DOPA pretreatment in the case of the thalamus and hypothalamus but not in that of the caudate nucleus or midbrain; atropine but not atropine methyl nitrate further lowered ACh levels in all brain parts. Diisopropyl phosphorofluoridate caused a decrease of NE levels and elevation of DA levels in all 4 brain parts of the pretreated rabbits. In identically pretreated animals atropine methyl nitrate given prior to DFP prevented the DA increase but was without effect upon the NE decrease in these brain parts. Dopamine was affected maximally in the hypothalamus, midbrain and thalamus concomitantly with major increments in ACh at these sites. Maximal decreases in NE occurred in the caudate, thalamus and midbrain; the extent of these changes did not parallel that of the changes in ACh. These findings confirm our earlier results (Glisson, Karczmar and Barnes, 1972) and expand them to additional brain parts. They are discussed with respect to brain localization of ACh and catecholamine systems.

Cholinergic effects on adrenergic neurotransmitters in rabbit brain parts

Abstract A cholinergic-adrenergic coupling in the case of the EEG antirecruitment effects of anticholinesterases in rabbits was demonstrated in this laboratory. To further investigate this phenomenon, experiments were carried out in rabbits to determine the effects of the anticholinesterase, diisopropyl phosphofluoridate (DFP), upon the levels of norepinephrine and dopamine in the midbrain-diencephalon and the caudate nucleus brain areas. Pretreatment with the monoamine oxidase inhibitor, JB835, and the monoamine precursor, dihydroxyphenylalanine (DOPA), caused an expected elevation in both the norepinephrine and dopamine levels in the midbrain-diencephalon and to a lesser extent in the caudate nucleus. When DFP was given to animals pretreated with JB835-DOPA combinations a significant decrease in the levels of norepinephrine was observed, while dopamine levels were markedly elevated, primarily in the midbrain-diencephalon. Both the norepinephrine decrement and the dopamine increment were partially blocked by atropine, while atropine methyl nitrate blocked only the elevation of the dopamine levels. It was concluded that the central actions of DFP result in the decrease of norepinephrine levels, while the dopamine levels become elevated in response to the peripheral effects of DFP. Certain aspects of the cholinergic-adrenergic coupling indicated by these experiments are discussed with regard to the localization of these two systems.

Di-isopropyl phosphofluoridate-induced antinociception: possible role of endogenous opioids

Di-isopropyl phosphofluoridate (DFP, 0.1--1.5 mg/kg, s.c.) produced antinociception in rats as measured by the hot plate test. Naloxone reduced DFP-induced antinociception but did not affect the attenuated locomotor activity or hypothermia produced by DFP. Animals rendered tolerant to the antinociceptive action of morphine failed to exhibit cross tolerance to the antinociceptive action of DFP. Morphine- and DFP-induced antinociceptive states were antagonized by MR 2266 and GPA 1843, the (-)-isomers of 5,9 alpha-Diethyl-2-(3-furylmethyl)-2-hydroxy-6, 7-benzomorphan and -2-allyl-2-hydroxy-9 beta-methyl-5-phenyl-6, 7-benzomorphan hydrochloride, respectively; the corresponding (+)-isomers, MR 2267 and GPA 1847, did not antagonize the antinociceptive state produced by DFP or morphine. These results suggest that DFP-induced antinociception may be mediated via the release of endogenous opioids; however, this could occur at sites different from those concerned with morphine tolerance.

Substance P-induced depolarization in sympathetic neurons: not simple K-inactivation

Ionic mechanisms underlying substance P-induced depolarization of the inferior mesenteric ganglion cells of the guinea pig were analyzed by means of microelectrode methods. When the membrane potential was manually clamped at the resting level, substance P caused, in about equal number of neurons, increases and decreases of neuronal input resistance. In the majority of the cells tested the amplitude of substance P-induced depolarization was increased when the membrane was hyperpolarized to the level of EK; it was markedly reduced in a Na+-free media. These results suggest that substance P causes depolarization by simultaneously increasing Na+ and decreasing K+ permeability.

Acetylcholine depolarization of the dorsal root nerve terminals in the amphibian spinal cord.

When ACh or carbachol was directly applied to the isolated amphibian spinal cord, a slow depolarization which originated at or near the dorsal root nerve terminals could be recorded by means of the sucrose-gap method. This depolarization was a transient phenomenon. A marked and transient decrease in the amplitude of the DR-DRP was observed during the development of the ACh depolarization. With relatively small concentrations of ACh, the reduced amplitude of the DR-DRP was gradually restored to an almost normal value within 30–40 min. The depolarization of the dorsal root nerve terminals as well as the reduction in the size of the DR-DRP, caused by ACh or carbachol, were enhanced by anti-AChEs and prevented by atropine, DHE, d-TC or nicotine. These pharmacological properties were similar to those of the VR-DRP. On the basis of the experimental observations, the possible location of the cholinoceptive receptor sites in the amphibian spinal cord was discussed.

Cholinergic substrates of cognition and organism-environment interaction

Abstract 1. 1. Several lines of evidence support the notion of cholinergicity of cognition and organism-environment interaction: a) Certain central pathways which were amply demonstrated as cholinergic in nature were also shown as significant for cognition and related processes; this is indicated by lesion experiments in animals and related evidence collected in man which includes that obtained in SDAT. b) Cholinergic agonists evoke a specific EEG alerting and hippocampal theta patterns that were shown to be the EEG counterparts of learning. c) The REM sleep reflects significant cholinergic correlates, and this phenomenology relates to the EEG components of cognition. d) Cholinergic agonists facilitate and cholinergic antagonists disrupt animal learning; in fact, beneficial effects were obtained with cholinergic agonists in animal models specifically designed to reflect impaired animal-environment interaction. e) Trophic factors restore cognition in lesioned animals and may exhibit similar action in human subjects suffering from cholinergic deficit. 2. 2. While many of these effects show that the cholinergic phenomena underlie cognitive facilitation and specific alerting, certain depressive symptoms are evoked in man and animals by muscarinic agonists. 3. 3. Altogether, it is speculated that, overall the central cholinergic function in awaken man and animals represents a cholinergic syndrome which relates to REM sleep and which exhibits a number of characteristic EEG, functional and behavioral phenomena. This syndrome is referred to as CANMB and its normal function underlies appropriate animal-organism interaction.

Contrasting behavioral, pharmacological, neurophysiological, and biochemical profiles of C57 B1/6 and SC-I strains of mice☆

APKNOW1EDGMB~T I wish to express my sincere gratitude to Dr. A. G. Karczmar for the kindness and patience that he has shown me as his graduate student and during the preparation of this thesis.