Frontotemporal dementia caregivers and researchers: partnering for brain donation.

This study utilized a community-based, participatory research model between the Association for Frontotemporal Degeneration (AFTD) and the Education Core of the Indiana Alzheimer Disease Center. A total of 30 caregivers of persons with frontotemporal dementia (FTD) participated in 6 focus groups in 3 cities. The majority of participants were spouses of the person with FTD and had been providing care for an average of 6 years. Transcript analysis revealed 7 prominent themes: willingness to participate, when/how the issue of brain donation is raised, who initiates discussion about brain donation, who is involved in decisions about brain donation, motivation for participating in brain donation, lack of effective communication, and barriers to research participation. Caregivers demonstrated a strong desire to participate in research and contribute to advancing knowledge. The lack of effective communication between the clinicians and caregivers was a barrier to developing positive rapport, detrimentally impacting research participation.

Effects of p53 mutations on apoptosis in mouse intestinal and human colonic adenomas.

We have examined the effects of inactivation of the p53 tumor suppressor gene on the incidence of apoptotic cell death in two stages of the adenoma-to-carcinoma progression in the intestine: in early adenomas where p53 mutations are rare and in highly dysplastic adenomas where loss of p53 occurs frequently. Homozygosity for an inactivating germ-line mutation of p53 had no effect on the incidence or the rate of progression of ApcMin/+-induced adenomas in mice and also did not affect the frequency of apoptosis in the cells of these adenomas. To examine the effect of p53 loss on apoptosis in late-stage adenomas, we compared the incidence of apoptotic cell death before and after the appearance of highly dysplastic cells in human colonic adenomas. The appearance of highly dysplastic cells, which usually coincides during colon tumor progression with loss of heterozygosity at the p53 locus, did not correlate with a reduction in the incidence of apoptosis. These studies suggest that p53 is only one of the genes that determine the incidence of apoptotic in colon carcinomas and that wild-type p53 retards the progression of many benign colonic adenoma to malignant carcinomas by mechanism(s) other than the promotion of apoptosis.

Phenotype of mice lacking functional Deleted in colorectal cancer (Dcc) gene.

The DCC (Deleted in colorectal cancer) gene was first identified as a candidate for a tumour-suppressor gene on human chromosome 18q. More recently, in vitro studies in rodents have provided evidence that DCC might function as a receptor for the axonal chemoattractant netrin-1. Inactivation of the murine Dcc gene caused defects in axonal projections that are similar to those observed in netrin-1-deficient mice but did not affect growth, differentiation, morphogenesis or tumorigenesis in mouse intestine. These observations fail to support a tumour-suppressor function for Dcc, but are consistent with the hypothesis that DCC is a component of a receptor for netrin-1.

Suppression of intestinal neoplasia by DNA hypomethylation.

We have used a combination of genetics and pharmacology to assess the effects of reduced DNA methyltransferase activity on ApcMin-induced intestinal neoplasia in mice. A reduction in the DNA methyltransferase activity in Min mice due to heterozygosity of the DNA methyltransferase gene, in conjunction with a weekly dose of the DNA methyltransferase inhibitor 5-aza-deoxycytidine, reduced the average number of intestinal adenomas from 113 in the control mice to only 2 polyps in the treated heterozygotes. Hence, DNA methyltransferase activity contributes substantially to tumor development in this mouse model of intestinal neoplasia. Our results argue against an oncogenic effect of DNA hypomethylation. Moreover, they are consistent with a role for DNA methyltransferase in the generation of the C to T transitions seen at high frequency in human colorectal tumors.

Behavioural effects of scopolamine and the TRH analogue RX77368 on radial arm maze performance in the rat.

Effects of repeated intracerebroventricular administration of the thyrotrophin-releasing hormone (TRH) analogue, RX77368 (3,3'-dimethyl-TRH, 2 µg, once daily), on a scopolamine-induced performance deficit in an eight-arm radial maze were evaluated in adult rats. Scopolamine (0.3 mg/kg i.p.-30 min) pre-treatment produced a significant deficit in the number of unrepeated arm entries and total arm entries and increased the percentage of incorrect arm entries and the total time on the maze, compared with saline-treated controls. Prior treatment with RX77368 (40 min before maze testing) produced a partial but significant attenuation of the scopolamine-induced performance deficit on the maze during the first five trials but RX77368 also enhanced maze performance during the same period when given alone. These results suggest that the observed scopolamine-induced performance deficit on the radial arm maze partly results from a reduction in locomotion and maze exploration rather than solely impairment of memory, and that RX77368 treatment may improve radial maze performance by increasing arousal and exploratory behaviour in rats rather than directly enhancing cognition.

Thyrotropin releasing hormone (TRH) and a degradation stabilized analogue (RX77368) stimulate phosphoinositide turnover in cultured astrocytes in a regionally specific manner.

Whilst the CNS effects of thyrotropin releasing hormone (TRH) may result from a direct action on neurones it is also a possibility that another cell type may mediate an indirect action. A potential candidate for such a role is the astrocyte. The ability of TRH and a stable analogue RX77368 (di-methyl proline TRH) to stimulate phosphoinositide turnover has been investigated in cultured astrocytes from a number of CNS regions. Significant increases in turnover were noted in three of the four regions studied. Percentage values were: in spinal cord, 33% TRH, 31% RX77368 (n = 15); in brain stem, 33% TRH, 37% RX77368 (n = 6); in cerebellum, 72% TRH, 73% RX77368 (n = 6); in cortex, 4% TRH, 13% RX77368 (n = 6). EC50 values for both peptides were in the picomolar range. These results indicate that some astrocytes in vitro possess functional TRH receptors linked to the phosphoinositide second messenger system and hence this cell type would potentially be capable of mediating an indirect action of the peptide. Also, because the response was limited to certain regions, heterogeneity in receptor expression is implied. Furthermore, in the light of other evidence to support astrocyte heterogeneity within a region, we suggest that certain characteristics of the response seen in our experiments may be the result of TRH receptors being restricted to a subpopulation of astrocytes within a given culture. Thus, our data show that astrocytes prepared from some CNS regions possess functionally coupled TRH receptors.

Anticonvulsant activity of the imidazoline 6,7-benzoidazoxan.

The effects of the imidazoline 6,7-benzoidazoxan on seizure threshold were assessed using standard tests of anticonvulsant activity. Benzoidazoxan (10-30 mg/kg i.p.; 100 mg/kg p.o.) prevented tonic, but not clonic, convulsions induced by electroshock in mice. The increase in seizure threshold was of rapid onset, and, although of short duration, was comparable with that obtained using phenytoin and sodium valproate. Moreover, unlike sodium valproate, benzoidazoxan was an efficacious anticonvulsant at doses (20, 30 mg/kg i.p.) which did not impair rotarod performance. The anticonvulsant effects of benzoidazoxan were confirmed using the maximal electroshock test in mice (median effective dose, 13.2 mg/kg i.p.) and rats (anticonvulsant at 30 mg/kg i.p.). In addition, benzoidazoxan (10, 30 mg/kg i.p.) prevented tonic, but not clonic, seizures induced by bicuculline in mice. Thus, the imidazoline benzoidazoxan was found to be a novel anticonvulsant agent against electrically and chemically induced seizures in mice and rats with a profile of action similar to that of phenytoin.

Exploring the pharmacology of the pro-convulsant effects of alpha 2-adrenoceptor antagonists in mice.

The effects of selective and specific alpha 2-adrenoceptor antagonists on electroshock seizure threshold in mice were investigated. Idazoxan, at low doses, efaroxan, RX811059 and RX821002 significantly lowered seizure threshold. The alpha 1-agonist St 587 and the beta-agonist isoprenaline were also pro-convulsant. On the other hand the alpha 2-agonists clonidine and UK 14,304 produced small increases in seizure threshold. Anticonvulsant effects were also produced by low doses of the noradrenaline uptake inhibitor desipramine. This compound increases levels of noradrenaline in the synaptic cleft which could subsequently act at post-synaptic alpha 2-adrenoceptors. The pro-convulsant action of alpha 2-adrenoceptor antagonists could be explained in terms of two mechanisms: a) blockade of endogenous noradrenaline which may normally exert a tonic anti-convulsant influence on seizure threshold, through post-synaptic alpha 2-receptors and/or b) increased activation of alpha 1- and beta-adrenoceptors by elevated synaptic noradrenaline levels following blockade of pre-synaptic alpha 2-adrenoceptors. Of the alpha 2-antagonists tested, idazoxan was unusual in that high doses were not pro-convulsant; this difference may be explained by alpha 1-adrenoceptor mediated actions or be related to its recently described affinity at a non-adrenoceptor site--a function for which is currently unknown.

Effects of idazoxan on 5-hydroxytryptamine-mediated behaviour in the mouse and rat.

The α(2)-adrenoceptor antagonists idazoxan and RX811059 induced reciprocal forepaw treading, a component of the 5-HT-behavioural syndrome in rats. This response is independent of 'non-α(2)-adrenoceptor idazoxan binding sites' (NAIBS) at which RX811059 is inactive. Idazoxan pre-treatment, in rats, enhanced forepaw treading, head weaving and tremor induced by the 5-HT agonist 5-methoxy-N,N dimethyltryptamine (5-MeODMT), increased head twitches (but decreased hindlimb abduction) induced by the 5-HT releaser p- chloroamphetamine (pCA), but did not clearly alter head twitches induced by the 5-HT precursor L-5-hydroxytryptophan in mice. The α(1)-antagonist prazosin did not alter behaviour induced by either 5-MeODMT or pCA in rats. The α( 2)-agonist, guanoxabenz, did not alter 5-MeODMT-induced behaviour in rats. St587, an α(1)-agonist, selectively potentiated tremor induced by 5-MeODMT, but no other behaviour. A possible mechanism for these interactions could be through enhanced, α(2)-adrenoceptor-mediated, 5-HT release in specific brain areas. Other possibilities, e.g. direct action at subtypes of 5-HT receptors and the importance of these NA-5-HT interactions in the treatment of resistant depression, are discussed.

Pharmacological and biochemical comparison of thyrotropin releasing hormone (TRH) and di-methyl proline-TRH on pituitary GH3 cells.

1. The binding of [3H]-thyrotropin releasing hormone ([3H]-TRH) and [3H]-RX77368 (di-methyl proline TRH) and the ability of these peptides to stimulate phosphoinositide hydrolysis were investigated in the GH3 pituitary cell line. 2. For both peptides binding was found to be saturable with a single component (Hill slopes were, for TRH, 0.98 and for RX77368, 1.13). TRH bound with greater affinity than RX77368 Kd values were 16 nM and 144 nM respectively. Bmax values were 227 fmol mg-1 protein for TRH and 123 fmol mg-1 protein for RX77368. 3. The rank order of potency of a series of TRH analogues to inhibit binding was the same versus each peptide. However, unlike with saturation analysis, Hill slopes of all displacing ligands were less than 1.0 against both TRH and RX77368 suggesting either multiple binding sites, alteration of affinity state, negative co-operativity or some allosteric interaction. 4. Both peptides stimulated phosphoinositide hydrolysis in a dose-dependent fashion. TRH was more potent than RX77368, EC50 values were 7.9 +/- 1 nM and 96.3 +/- 3 nM respectively. 5. These in vitro data suggest that the greater in vivo potency of RX77368 is not the result of enhanced receptor affinity but is more probably due to its greater metabolic stability.

Specific α2-adrenoreceptor antagonists induce behavioural activation in the rat.

The behavioural effects of the specific and selective α(2)-adrenoreceptor antagonists, idazoxan, efaroxan and RX811059, have been investigated in the rat. All three drugs induced periods of behavioural activation characterized by increased locomotion and exploration (rearing and hole dipping). However, these effects were only apparent in animals which were fully habituated to their environments and thus displayed low baseline activity. The behaviour observed lay within the normal range of activity and was not apparent under conditions when exploration was stimulated such as in a novel environment. α( 2)-Adrenoreceptor antagonist- induced activation was a weak response when compared with the intense and prolonged hyperactivity, in both novel and non-novel environments, induced by the amine releaser D- amphetamine. Possible mechanisms involving a direct action of noradrenaline at postsynaptic α( 1)-adrenoreceptors (subsequent to enhanced presynaptic α(2)-receptor feedback blockade) or an indirect action of α(2)-antagonists on dopamine function in mesolimbic pathways are discussed.

Alpha 1- and alpha 2-adrenoreceptor antagonists differentially influence locomotor and stereotyped behaviour induced by d-amphetamine and apomorphine in the rat.

The importance of dopamine (DA) in mediating locomotor, exploratory and stereotyped behaviour in rodents is well established. Evidence also indicates a modulatory role for noradrenaline (NA) although, due to nonspecificity. of previously available agents, a precise role remains undefined. The effects of the specific and selective alpha-adrenoreceptor antagonists idazoxan (alpha 2) and prazosin (alpha 1) on behaviour induced by amphetamine and apomorphine have been investigated in the rat. d-Amphetamine (2 mg/kg) induced hyperactive locomotion and exploration. Pretreatment with prazosin (1 mg/kg) markedly reduced these responses. In contrast, pretreatment with idazoxan (20 mg/kg) only marginally altered d-amphetamine hyperactivity. Apomorphine (0.5 mg/kg) induced biphasic locomotor and exploratory activity. Neither alpha-antagonist affected the initial burst of activity (60 min), although prazosin inhibited whereas idazoxan potentiated the secondary phase (90-180 min). At higher dosage, amphetamine (6 mg/kg) and apomorphine (2 mg/kg) induced stereotyped behaviours. Prazosin pretreatment enhanced stereotyped gnawing and decreased sniffing and locomotion, whereas idazoxan increased locomotion and decreased amphetamine-induced mouth movements. These data indicate that DA-induced locomotor and stereotyped behaviours are differentially influenced (in opposite directions) by both alpha1- and alpha 2-adrenoreceptor antagonists. NA may thus modulate the expression and character of behaviour by influencing DA function in certain brain areas.

5-Hydroxytryptamine-mediated behaviour in male and female rats.

The responses of male and female rats to drugs causing the behavioural syndrome induced by 5-hydroxytryptamine (5-HT) were compared. Preliminary experiments showed that females had largely similar responses to the releaser of 5-HT, p-chloroamphetamine (PCA) and the 5-HT receptor agonist 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) at different stages of the oestrus cycle. The behavioural responses to 5-MeODMT (with and without the monoamine oxidase inhibitor pargyline) or to p-chloroamphetamine were not significantly different to those of males except for tremor after p-chloroamphetamine which was more marked in the females. However, concentrations of p-chloroamphetamine in brain in these animals, when killed immediately after behavioural recording were greater in the females. When rats, pretreated with the monoamine oxidase inhibitor, pargyline, were given the precursor of 5-HT, tryptophan, the females showed substantially greater hypothermia and larger scores for components of the 5-HT syndrome than the males. This sex difference may have been due to the moderately but significantly higher levels of 5-HT (and possibly tryptamine) in brain attained by the female rats, than by similarly-treated males. The results as a whole therefore suggest that the greater behavioural response of female rats to pargyline and tryptophan reflects a greater effect of this treatment on the synthesis of indoleamines than that occurring in males.

Central serotonergic responses and behavioural adaptation to repeated immobilisation: the effect of the corticosterone synthesis inhibitor metyrapone.

Rats were immobilised for 2 h/day. Twenty-four hours after the 1, 3 or 7 immobilisation periods they were injected with the 5HT agonist 5-methoxy-N,N-dimethyltryptamine (5MeODMT; 5 mg/kg i.p.) and behavioural responses (i.e. hind limb abduction, forepaw treading, head weaving, tremor, Straub tail) compared with those of a control group. As we have previously observed after 7 (but not after 1 or 3 immobilisations) forepaw treading and tremor were enhanced and the other responses unaffected. Pretreatment with metyrapone (a corticosterone synthesis inhibitor 150 mg/kg i.p., 3 h before each immobilisation) did not affect the above responses to 1 immobilisation, increased tremor after 3 immobilisations and also increased forepaw treading, hind limb abduction and Straub tail after 7 immobilisations but decreased head weaving under the latter conditions. Metyrapone without immobilisation had no effect on responses to 5MeODMT. Twenty four hours after 1 or 3 (but not 7) immobilisation periods, rats placed for the first time in an open field showed less locomotion and rearing and more defaecation than control animals. Rats also given metyrapone exhibited normal open field behaviour after only 3 immobilisations. The drug also accelerated the return to normal on repeated immobilisation of the impairment of food intake and growth rate which occurred after a single immobilisation. The results as a whole suggest that metyrapone promotes behavioural adaptation to repeated immobilisation and that this is associated with enhanced postsynaptic responses to 5HT. These findings suggest that immobilisation stress-induced changes might be relevant as an animal model for depression which incorporates reported biochemical abnormalities in the illness and is of relevance to proposals concerning its precipitation by stress.

Reduced-5-hydroxytryptamine-dependent behavior in rats following chronic corticosterone treatment.

The effect of chronic corticosterone treatment (50 mg/kg s.c. 2 x daily) for up to 4 days on behavioural responses to drugs affecting 5-hydroxytryptamine (5-HT) and dopamine (DA) systems was examined in rats 20 h after the last treatment, when placed in experimental cages, to which they had become habituated. Corticosterone- and vehicle-treated rats exhibited both comparable spontaneous behavior when given 0.9% NaCl i.p. and showed similar behavioural responses following amphetamine (3 mg/kg i.p.). However, responses to the 5-HT-releasing drug p-chloroamphetamine (PCA, 4 mg/kg i.p.) were altered with decreased head-weaving hind-limb abduction and forepaw treading. Postsynaptic changes appear to be involved as responses to the 5-HT agonist 5-methoxy-N,N-dimethyltryptamine (5-MeODMT, 5 mg/kg i.p.) (tremor, hind-limb abduction and forepaw treading) were also decreased. Hind brain and striatal concentration of 5-HT, DA and their metabolites were comparable in corticosterone and vehicle treated rats killed 20 h after the last treatment. Brain PCA levels determined 30 min after injection were also comparable in both groups. PCA induced behaviour was not altered 20 h after 1 day corticosterone treatment or 4 day after 1 day treatment and 5-MeODMT-induced behaviour was not altered 20 h after 14 days treatment with a lower dose of corticosterone (10 mg/kg s.c. x 2). Twenty h after 1 day corticosterone treatment (50 mg/kg s.c. x 2), rats placed in an open field for the first time showed significantly more activity and dropped fewer faecal pellets than controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhancement of some 5-HT-dependent behavioural responses following repeated immobilization in rats.

Responses to drugs affecting 5-hydroxytryptamine (5-HT) and dopaminergic (DA) system have been examined in rats after repeated immobilization. Groups of rats were immobilized for 2 h per day for up to 7 days. Twenty-four hours later their behavioural responses to various drugs were tested. Rats immobilized for 7 days showed decreased sniffing and increased grooming and body shakes. When given amphetamine (3 mg/kg, i.p.) the intensity of classical dopamine-dependent behaviours was similar to that of non-immobilized controls. Some responses to the 5-HT releaser p-chloroamphetamine (PCA) (4 and 10 mg/kg, i.p.) and the 5-HT agonist 5-methoxy-N,N-dimethyltryptamine (5-MEODMT) (5 mg/kg, i.p.) (forepaw treading and tremor) were enhanced after 7 days immobilization but others (limb abduction and headweaving) were not. These responses were not enhanced after 1 or 3 days immobilization. Backward walking and body shakes induced by PCA were also enhanced after 7 days immobilization. Concentrations of 5-HT, DA and their metabolites in striatum, cortex, hippocampus, hypothalamus and midbrain of non-drug-treated control and immobilized groups were comparable. Brain PCA concentrations 30 min after injection were also comparable. The above biochemical and behavioural data suggest that repeated immobilization increases some 5-HT postsynaptic functions. These results are discussed in relation to non-drug-provoked behavioural abnormalities occurring 24 h after the first immobilization but no longer evident after 7 periods of immobilization.

The effects of lesions produced by 5,7-dihydroxytryptamine on 5-hydroxytryptamine-mediated behaviour induced by amphetamine in large doses in the rat.

The role of 5-hydroxytryptamine (5-HT)-containing terminals in the spinal cord and basal ganglia in behavioural responses induced by amphetamine in large doses have been investigated using the neurotoxin for 5-HT, 5,7-dihydroxytryptamine (5,7-DHT). The effects of pretreatment with 5,7-DHT were also examined using the 5-HT agonist, 5-methoxy-N,N-dimethyltryptamine (5-MeODMT). d-Amphetamine (25 mg/kg) induced several classical 5-HT-dependent behavioural responses (head weaving , forepaw treading, hind limb abduction, "wet dog" shakes, Straub tail), together with some classical dopamine (DA)-dependent behaviour and backward locomotion which requires both transmitters. Pretreatment with 5,7-DHT, given into the striatum significantly decreased "wet dog" shakes and virtually abolished backward walking. Pretreatment with 5,7-DHT in the nucleus accumbens or substantia nigra did not significantly alter behaviour. Pretreatment with 5,7-DHT intraspinally did not significantly alter behaviour induced by amphetamine, although a decrease of Straub tail just failed to reach significance (P = 0.056). Similar pretreatment in rats given 5-MeODMT (8 mg/kg) significantly enhanced both Straub tail and tremor but did not alter the other behavioural responses induced by this drug (limb abduction, forepaw treading, head weaving ). The results in general suggest that behavioural responses induced by 5-HT can be classified into 3 groups (a) those requiring striatal 5-HT ("wet dog" shakes and backward locomotion), (b) those requiring spinal 5-HT (Straub tail, tremor) and (c) those requiring neither spinal nor striatal 5-HT (hind limb abduction, head weaving and forepaw treading).

Roles of dopamine and 5-hydroxytryptamine in stereotyped and non-stereotyped behaviour.

The roles of dopamine (DA) and 5-hydroxytryptamine (5-HT) in stereotyped and non-stereotyped components of the classical behavioural syndromes induced by 5-HT and DA were investigated by studying (a) behavioural interactions between the DA agonist apomorphine and the 5-HT agonist 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) and (b) the effects of depletion of 5-HT on the behavioural responses to amphetamine and p-chloroamphetamine. In agreement with evidence [Andrews, Fernando and Curzon (1982) Neuropharmacology 21:63-68] that non-stereotyped (i.e. body shakes and hind limb abduction) and stereotyped (i.e. head weaving and reciprocal forepaw treading) behaviour induced by d-amphetamine (25 mg/kg, i.p.) were inhibited and enhanced respectively by DA, apomorphine inhibited two non-stereotyped behavioural responses induced by 5-MeODMT (hind limb abduction and Straub tail) but enhanced reciprocal forepaw treading. However, head weaving was inhibited. Evidence indicated that behaviour induced by DA (whether stereotyped or not) was inhibited by 5-HT. Thus, the induction by apomorphine of sniffing and mouth movements was enhanced when the synthesis of 5-HT was inhibited. Also, p-chloroamphetamine caused sniffing and mouth movements only when 5-HT synthesis was inhibited. Under the latter conditions, while most classical behavioural responses associated with 5-HT did not occur, hind limb abduction persisted. Similarly, amphetamine (25 mg/kg) caused hind limb abduction and forepaw treading even when 5-HT was almost completely depleted. These results may indicate that the amine releasers have some direct 5-HT agonist properties. Results in general indicate the multiplicity of behavioural interactions between DA and 5-HT.