Notes: Summary Glucocorticoid receptor (GR) immunoreactivity (IR) was analyzed semi-automatically in the forebrain and in the lower brain stem of male rats treated for two weeks with imipramine (10 μmol/kg). Serum corticosterone and aldosterone levels were determined by means of radioimmunoassay procedures. The microdensitometric analysis demonstrated a selective increase in the GR IR in the nerve cell nuclei of the locus coeruleus (A6), of the ventral part of the reticular gigantocellular nucleus (B3L) and of the nucleus raphae magnus (B3M), whereas a small reduction of GR IR was found in the nucleus raphe obscurus (B2). In the morphometric analysis significant increases in the mean profile area of nuclear GR IR, which may be secondary to the increase in GR IR, were observed in the B3M. The serum corticosterone and aldosterone levels were not found to be significantly altered. The selective changes of GR IR may reflect the presence of an altered number of GR in these nerve cell groups and/ or an altered translocation of GR to the nuclei. It is of substantial interest that these changes were observed in the presence of unchanged serum levels of corticosterone and aldosterone. It seems possible that adaptive changes in monoamine synapses induced by the chronic imipramine treatment may be responsible for the changes in GR IR found in the noradrenaline (NA) and 5-hydroxytryptamine (5-HT) cell bodies, respectively. The present results open up the possibility that chronic imipramine treatment may help to maintain the glucocorticoid receptor function in the locus coeruleus and in the 5-HT cell groups of the rostral ventromedial medulla of depressed patients.

Notes: Summary Groups of male rats were treated for a period of 14 days with imipramine (10Μmol/kg) given twice daily. Separate groups of rats received a single dose treatment using the same dose and experimental design as for the repeated treatment. Employing the avidin-biotin immunoperoxidase technique for immunohistochemistry 5-hydroxytryptamine (5-HT)-, substance P (SP)- and thyrotropin releasing hormone (TRH)-like immunoreactivities (IRs) were visualized in consecutive coronal sections of the brain stem and of the spinal cord. The IRs were studied by means of morphometric and microdensitometric procedures using automatic image analysis on profiles representing nerve terminal networks of the ventral horn of the cervical and lumbar enlargements of the spinal cord as well as their coexistence (5-HT/SP and 5-HT/TRH). With the same technique 5-HT IR was measured in the 5-HT nerve cell groups of the medulla oblongata (B 1, B 2, B 3) and of the nucleus raphe dorsalis (B 7) of the midbrain. In addition 5-HT and 5-hydroxyindolacetic acid (5-HIAA) levels were measured in the ventral and dorsal horns of the cervical and lumbar enlargements of the spinal cord using high performance liquid chromatography (HPLC). In the same parts of the spinal cord SP IR was studied by means of radioimmunoassay (RIA). The microdensitometric studies showed that chronic, but not acute, imipramine treatment selectively increased SP IR in the 5-HT/SP/TRH costoring nerve terminals of the medial part of the ventral horn in both the cervical and the lumbar enlargements. Furthermore, quantitative analysis of the entity of coexistence in the 5-HT nerve terminal networks of these areas showed that all the 5-HT nerve terminals contained SP and TRH IRs and that this phenomenon remained after acute and chronic imipramine treatment. The microdensitometric studies on the 5-HT nerve cell groups of the medulla oblongata and of the nucleus raphe dorsalis demonstrated that chronic, but not acute, imipramine treatment selectively increased 5-HT IR in the nerve cell bodies of the lateral part of group B 3 as evaluated from the median grey values. Acute, but not chronic, imipramine treatment significantly increased the field area of 5-HT IR of nerve cell bodies in group B 7, reflecting an increase in the mean profile area of the 5-HT IR nerve cell body profiles. Instead, the mean profile area of 5-HT IR cell bodies of group B 1 was acutely reduced by imipramine. The biochemical studies demonstrated that chronic imipramine treatment selectively reduced 5-HT utilization in the ventral horn of the spinal cord and selectively increased SP IR in the dorsal horn of the lumbar enlargement. In view of these observations it is suggested that chronic imipramine treatment specifically increases SP IR in the 5-HT/SP/TRH costoring nerve terminals of the ventral horn probably related to reduced SP release and reduced 5-HT utilization in these terminals. The results obtained in group B 7 may be explained by a regulation by the3H-imipramine raphe binding sites of fast axonal transport, an influence which may have therapeutic consequences. This mechanism may also be responsible for the increase in 5-HT IR seen upon chronic imipramine treatment in the lateral part of the 5-HT nerve cell body group B 3. Such an effect may lead to a metabolic down-regulation of group B 7, having a possible role for the antidepressant activity of imipramine. The reduction of the mean profile area of 5-HT IR cell bodies of group B 1 seen in the acute treatment can possibly be caused by, noradrenaline (NA) uptake inhibition in inhibitory NA terminals innervating the B 1 group. These results also illustrate the heterogeneities in the responses of the 5-HT nerve cell groups to antidepressant treatment. The ability of chronic imipramine treatment to increase SP IR in the dorsal horn of the lumbar enlargement may reflect the existence of a monoamine-SP interaction in the substantia gelatinosa due to the NA and/or 5-HT uptake blocking activity of imipramine. The existence of such an interaction may help to explain the antinociceptive effect of chronic imipramine treatment.

Notes: Summary Male rats were exposed to severe 14 day immobilization stress. Body weight, body temperature, food and water intake, behavioral parameters, and serum corticosterone levels were measured during and after the stress period. On the 7th day after cessation of stress the experimental animals together with the control rats were taken to immunocytochemical analysis involving morphometry and microdensitometry of tyrosine hydroxylase (TH), 5-hydroxytryptamine (5-HT), various neuropeptide, and glucocorticoid receptor (GR) immunoreactivities (IRs) in a large number of regions of the central nervous system. In addition, adrenocorticotropic hormone (ACTH) IR was analyzed in the pituitary gland. Seven days following cessation of the chronic stress food intake, total locomotion and forward locomotion had been restored to normal. Serum corticosterone levels appeared to remain increased even 6 days following cessation of the chronic immobilization stress, probably caused by increased release of ACTH. Paraventricular corticotropin releasing hormone (CRF) IR was negatively correlated with the pituitary ACTH IR, indicating that the increase in ACTH release was produced by an increased release of CRF from the hypothalamus. The major immunocytochemical change observed 7 days after cessation of stress was a disappearance of 5-HT IR in the 5-HT cell groups B 1, B 2, B 3, and B 7. 5-HT IR in nerve terminals was only affected in the dorsal horn, where 5-HT IR was increased in the substantia gelatinosa. GR IR was found to be significantly increaed in monoaminergic cell groups: serotoninergic B 7, dopaminergic A 12, and noradrenergic A 1, A 2, and A 6. A trend for a reduction of TH IR was observed in nigral DA cells associated with significant reductions in TH IR in striatal DA nerve terminals. Finally, increases in 5-HT and substance P (SP) IR were found in the nerve terminals of the substantia gelatinosa of the cervical spinal cord in the stress group. In the present experimental model evidence has been obtained for a maintained activation of the hypothalamic-pituitary-adrenal axis as evaluated 7 days after cessation of severe chronic immobilization stress. The reduction of 5-HT IR in various 5-HT cell groups indicates a reduction of 5-HT synthesis, which may also be associated with reduced 5-HT release from the nerve terminals, since no depletion was observed in terminal regions and in one case an increase in 5-HT IR was noted (substantia gelatinosa). The increase in GR IR, demonstrated in the NA and 5-HT cell groups in the presence of a maintained hypersecretion of corticosterone may represent signs of an upregulation of GR synthesis and/or increased translocation, which take place in the presence of maintained hypersecretion of corticosterone. Thus, 5-HT and NA neurons may respond more effectively to circulating glucocorticoids after severe chronic stress. In this way glucocorticoids may protect against stress-induced exhaustion of neurons leading to impairment of transmission. Studies on TH IR suggest a deficit in the DA transmission line of the nigrostriatal DA neurons, but of no other CA neurons studied. Such effects may contribute to behavioral suppression. Finally, the stress-induced increases in 5-HT and SP IR in the substantia gelatinosa may in part underlie the phenomenon of stress-induced analgesia.

Notes: Summary Evidence exists for a negative correlation between Parkinson's disease and smoking. The present and previous studies indicate that nicotine treatment can markedly alter the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in the black mouse based on biochemical determinations of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels in neostriatum and substantia nigra 2 weeks after MPTP injection. Acute intermittent treatment with (−)nicotine starting 10 min before the MPTP injection partly protected against MPTP-induced neurotoxicity in the neostriatum and substantia nigra. Also, a partial protection was observed in the substantia nigra when (−)nicotine was given together with MPTP in an acute intermittent treatment schedule. Conversely, chronic infusion of (−)nicotine via minipumps produced a dose-related enhancement of MPTP-induced DA neurotoxicity in the neostriatum. It is suggested that the protective activity of nicotine in the MPTP model is related to a blockade of MPP + uptake into the DA cells via increased DA release. Conversely, the nicotine enhancement of MPTP-induced DA toxicity is suggested to be caused by a failure of the nicotinic cholinoceptors to desensitize to the chronic (−)nicotine exposure, leading to increased chronic influx of Na+ and Ca2+ ions via the ion channels of the nicotinic cholinoceptors located on the DA neurons with associated increased Ca ion toxicity and increased energy demands.

Notes: Summary Based on the observations that the psychostimulant drug amphetamine in combination with physiotherapy can promote recovery of brain function after brain injury, we have studied the ability of the vigilance promoting drug Modafinil to counteract 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-(MPTP)-induced degeneration of the nigrostriatal dopamine (DA) neurons of the black mouse. MPTP was given s.c. in a dose of 40 mg/kg and the mice were sacrificed 2 weeks later. The effects of acute and chronic treatment with Modafinil were studied on MPTP-induced DA neurotoxicity. The substantia nigra and neostriatum were taken to both biochemical and histochemical analysis of presynaptic parameters of the nigrostriatal DA neurons, the latter in combination with image analysis. In separate experiments in rats in vivo tests for DA uptake blocking activity were made using intrastriatal microdialysis to study superfusate levels of DA and its metabolites and the 4-α-dimethylmetatyramine (H77/77) model to test for a possible ability of Modafinil to protect against H77/77-induced depletion of forebrain DA stores. Chronic treatment with Modafinil in doses of 10 to 100 mg/kg counteracted the MPTP-induced disappearance of nigral TH IR nerve cell body profiles and neostriatal TH IR nerve terminal profiles as evaluated after 2 weeks with image analysis. Chronic treatment with Modafinil (10–100 mg/kg) also dose-dependently counteracted the MPTP-induced disappearance of striatal DA uptake binding sites as evaluated at the same time interval. Also in the dose range 10–100 mg/kg Modafinil counteracts the MPTP-induced depletion of DA stores both in the neostriatum and the substantia nigra. In the acute experiments Modafinil (30 mg/kg) protected against the MPTP-induced depletion of striatal DA, dihydrophenylacetic acid (DOPAC) and homovanillic acid (HVA) levels both when given 15 min before, at the same time and 3 h following the MPTP injection. In the substantia nigra, however, these protective actions of Modafinil were only observed when the drug was coadministered with MPTP. Experiments with microdialysis in intact rats failed to demonstrate any increases of superfusate DA levels in neostriatum with 30 mg/kg of Modafinil. Modafinil in high doses of 2 × 50 mg/kg, however, significantly counteracted the H77/77 induced DA depletion of striatal DA stores. Thus, morphological and biochemical evidence has been obtained that Modafinil in the dose range 10–100 mg/kg protects against MPTP-induced degeneration of the nigrostriatal DA neurons of the black mouse. The results also indicate that the protective action of Modafinil is not caused by monoamine oxidase inhibition or by DA uptake inhibition, although the latter action may contribute in the highest dose used (100 mg/kg). Instead, it is hypothesized that its protective action may be related to actions on GABAergic mechanisms as evidenced by reduced cortical GABA outflow in doses of 3–30 mg/kg (Tanganelli et al. 1991) and/or to other unknown mechanisms.

Notes: Summary Morphological changes in ventral mesencephalic dopamine (DA) neurons of a monkey sustaining a unilateral electrolytic lesion of the ventromedial mesencephalic tegmentum four years earlier were examined. Substantia nigra (A9) DA neurons lateral to the lesion underwent hypertrophic changes. The mean area of these neurons was enlarged by approximately 30% relative to corresponding neurons in the contralateral substantia nigra. Semi-quantitative immunohistochemical measurements of the intensity of tyrosine hydroxylase-like immunoreactivity (TH-li) indicated an increase in the amount of TH-li protein per cell in the hypertrophied neurons. Hypertrophic changes were also observed in ipsilateral A11 DA neurons of the caudal hypothalamus, suggesting that the increase in size was related to transection of the axons of DA neurons as they pass through the midbrain in their projections to target sites. The lesion did not overtly change the density or pattern of the substance P innervation of the substantia nigra, indicating that the striato- and pallido-nigral projections were spared by the lesion. These data suggest that hypertrophy may be a compensatory mechanism of dopaminergic neurons in response to partial lesions of the nigrostriatal system, and thus represent a morphological counterpart to the compensatory biochemical processes effected in response to partial lesions of the striatal dopaminergic innervation.

Notes: Abstract Basic fibroblast growth factor (bFGF, FGF-2) is a trophic factor for neurons and astrocytes and has recently been demonstrated in the vast majority of dopamine (DA) neurons of the ventral midbrain of the rat. Potential neuroprotective actions of FGF-2 in the l-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP) model have also been reported. The actions of the FGF-2 have now been further analyzed in a combined morphological and behavioural analysis in the MPTP model of the adult black mouse, using a continuous human recombinant FGF-2 (hrFGF-2) intraventricular (i.v.t.) administration in a heparin-containing (10 IU heparin/ml) mock cerebrospinal fluid (CSF) solution. Tyrosine hydroxylase (TH) immunocytochemistry in combination with computer assisted microdensitometry demonstrated a counteraction of the MPTP-induced disappearance of neostriatal TH-immunoreactive (ir) nerve terminals following the FGF-2 treatment. Unbiased estimates of the total number of nigral TH ir neurons, using stereological methods involving the optical disector (Olympus), showed that the MPTP-induced reduction in the number of nigral TH ir nerve cell bodies counterstained with cresyl violet (CV; by 56%) was partially counteracted by the FGF-2 treatment (by 26%). The behavioral analysis demonstrated an almost full recovery of the MPTP-induced reduction of the locomotor activity after FGF-2 treatment. This action was maintained also 1 week after cessation of treatment. The hrFGF-2 produced an astroglial reaction as determined in the lateral neostriatum and in the substantia nigra (SN) far from the site of the infusion, indicating that the growth factor may have reached these regions by diffusion to activate the astroglia. Immunocytochemistry revealed FGF-2 immunoreactivity (IR) in the nuclei of the astroglia cell population in the dorsomedial striatum and the microdensitometric and morphometric evaluation demonstrated an increase in the number, but not in the intensity, of these profiles on the cannulated side, suggesting the possibility that hrFGF-2 stimulates FGF-2 synthesis in astroglial cells with low endogenous FGF-2 IR. These results indicate that hrFGF-2, directly and/or indirectly via astroglia, upon i.v.t. infusion exerts trophic effects on the nigrostriatal DA system and may increase survival of nigrostriatal DA nerve cells exposed to the MPTP neurotoxin.

Notes: Abstract We studied the ability of the vigilance-promoting drug modafinil to modulate the anterograde and retrograde changes in tyrosine hydroxylase (TH) immunoreactivity and in dopamine (DA) stores in the nigro-neostriatal DA neurons, following a partial hemitransection of this ascending DA system, using a combined morphometrical, biochemical and behavioural analysis. Modafinil was given daily i.p. in doses of 10–100 mg/kg, starting 15 min after the lesion, and the partially hemitransected rats were killed 2 weeks later. Changes in TH-immunoreactive nerve cell bodies and nerve terminals induced by the partial hemitransection were studied in the substantia nigra and neostriatum in combination with image analysis. The substantia nigra and neostriatum were also subjected to biochemical analysis of DA, 3,4-dihydroxyphenylacetic acid and homovanillic acid levels. Modafinil treatment dose-dependently (10–100 mg/kg) counteracted the hemitransection-induced disappearance of nigral TH-immunoreactive nerve cell body profiles and neostriatal TH-immunoreactive nerve terminal profiles. A 2-week treatment with 100 mg/kg of modafinil also counteracted the hemitransection-induced depletion of DA stores in the neostriatum and the ventral midbrain. Moreover, the repeated daily treatment with modafinil (100 mg/kg) protected against the hemitransection-induced disappearance of striatal 5-hydroxytryptamine, 5-hydroxyindoleacetic acid and noradrenaline levels. Striatal DA function was analysed by studying apomorphine-induced (1 mg/kg, s.c.) ipsilateral rotational behaviour 4 and 11 days after the operation. A marked dose-dependent reduction of ipsilateral rotational behaviour was demonstrated after the daily modafinil treatment in the partially hemitransected rats. In another model involving unilateral nigral microinjections of 6-hydroxydopamine, acute (one single dose) modafinil (100 mg/kg) did not affect the contralateral rotational behaviour induced by apomorphine (0.05 mg/kg s.c.), when given 30 min before the apomorphine. Taken together, morphological, neurochemical and behavioural evidence has been obtained that anterograde and retrograde changes induced in the DA stores and TH immunoreactivity of the nigro-neostriatal DA neurons by a partial hemitransection are counteracted by modafinil in a dose dependent way with 100 mg/kg producing a significant protective action against impairment of DA transmission. The results of this study open up the possibility that modafinil may protect against the anterograde and retrograde degeneration of nigrostriatal DA neurons seen after mechanically induced injury.

Notes: Summary The effects of modafmil on acetylcholine and GABA outflow from the cerebral cortex of awake freely moving guinea pigs provided with an epidural cup were studied. In the dose range of 3–30 mg/kg s. c. modafmil produced a dose dependent significant inhibition of GABA outflow without influencing cortical acetylcholine release. Methysergide (2 mg/kg, i.p.) and ketanserin (0.5 mg/kg, i. p.) but not prazosin (0.14 mg/kg, i. p.) counteracted the inhibitory action of modafinil on cortical GABA outflow. Modafinil both acutely and chronically in the same dose range increased striatal 5-HIAA levels and 5-HT utilization in the rat (acute) and mouse (chronic). The action on cortical GABA release may be dependent on activity at 5-HT2 receptors, since the action of modafmil in this respect is blocked by the non-selective 5-HT antagonist methysergide and the 5-HT2 antagonist ketanserin. The involvement of 5-HT mechanisms in the inhibitory action of modafmil on cortical GABA release is also suggested by the findings that 5-HT metabolism may become increased by modafmil at least in the striatum. The reduction of cortical GABA outflow via 5-HTZ receptors by modafmil is probably related to some of its actions on the central nervous system including behavioural effects.