| 1. |
- Cenci Nilsson, Angela, et al.
(författare)
-
Striatal c-fos Induction by Cocaine or Apomorphine Occurs Preferentially in Output Neurons Projecting to the Substantia Nigra in the Rat
- 1992
-
Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 4:4, s. 376-380
-
Tidskriftsartikel (refereegranskat)abstract
- Fluorogold or rhodamine-labelled latex beads were injected in the substantia nigra (SN) or the globus pallidus (GP) in order retrogradely to label striatal output neurons that project to the two target structures. Ten days later, striatal c-fos was induced by systemic administration of cocaine (five normal rats; 25 mg/kg cocaine i.p. 2 h before killing) or apomorphine (five unilaterally dopamine-denervated rats; 0.25 mg/kg apomorphine s. c. 2 h before killing), and detection of the Fos protein in the striatum was achieved by immunofluorescence. Sections through the caudate-putamen that displayed good labelling from both SN and GP were selected for a quantitative analysis: the number of retrogradely labelled cells that exhibited Fos immunoreactivity, as well as the total number of retrogradely labelled cells located within a grid (0.16 mm2 in size) were counted manually at 25 x magnification. Cocaine induced a proportionally higher c-fos expression in striato-nigral compared to striato-pallidal neurons, whereas apomorphine activated Fos almost exclusively in striato-nigral neurons. The present findings are consistent with the idea that striatal c-fos induction by dopaminergic agents is primarily mediated by an interaction with D1-receptors, which are thought to be selectively localized on neurons projecting to SN.
|
|
| 2. |
- Guillery, Ray, et al.
(författare)
-
Editorial note
- 1990
-
Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 2:7, s. 565-565
-
Tidskriftsartikel (refereegranskat)
|
|
| 3. |
- Kalén, Peter, et al.
(författare)
-
Host Brain Regulation of Fetal Locus Coeruleus Neurons Grafted to the Hippocampus in 6-Hydroxydopamine-Treated Rats. An Intracerebral Microdialysis Study
- 1991
-
Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 3:9, s. 905-918
-
Tidskriftsartikel (refereegranskat)abstract
- Release properties of intrahippocampal transplants of noradrenergic neurons were monitored by microdialysis in awake and halothane-anaesthetized rats. Fetal locus coeruleus neurons were implanted as a cell suspension into hippocampi deprived of their innate noradrenalin (NA) innervation by intraventricular 6-hydroxydopamine treatment. Dialysis probes of the loop type were implanted into the dorsal hippocampus 1 - 2 days before each experiment, i.e. 7 - 11 months after grafting. Age-matched intact and lesion-only animals served as controls. Microscopic analysis showed a graft-derived tyrosine hydroxylase immunoreactive, presumably noradrenergic, fibre network throughout the dorsal hippocampal formation, surrounding the probe site. The innervation density varied from sub- to supranormal. The grafts restored baseline NA release in the graft-reinnervated hippocampus to near-normal levels both in awake and halothane-anaesthetized animals. Potassium chloride (100 mM) in the perfusion fluid induced a dramatic increase in NA release that was similar in magnitude in the grafted and intact hippocampi. A NA uptake blocker (desipramine) added to the perfusion fluid at 5 microM induced a similar increase in NA output in the grafted and intact hippocampi, and the output was substantially reduced by tetrodotoxin, added at 1 microM in the presence of uptake blockade. Electrical stimulation of the lateral habenular nucleus (15 Hz, 0.5 mA) in halothane-anaesthetized rats induced a significant increase in NA output both in the intact and grafted hippocampi. This effect was abolished by transection of the fasciculus retroflexus, which carries the efferent projections of the habenular complex. Behavioural activation through handling induced a consistent increase in NA release only in the intact animals, but in a few grafted rats (which also responded to habenular stimulation) the NA output was clearly elevated by handling. Forced immobilization induced a significant increase in NA output both in the intact and grafted hippocampi, but in the grafted ones the response was somewhat smaller and more transient. In the same set of animals, swimming in warm water (25 - 30 degrees C) induced a sharp increase in NA output in the intact animals, whereas only one of the grafted rats responded by increased NA output. The results indicate that the locus coeruleus grafts, despite their ectopic location, can become functionally integrated with the host brain, and that the activity of the transplanted noradrenergic neurons can, under some circumstances, be modulated from the host brain in response to environmental challenges.
|
|
| 4. |
- Kokaia, Merab, et al.
(författare)
-
Seizure development and noradrenaline release in kindling epilepsy after noradrenergic reinnervation of the subcortically deafferented hippocampus by superior cervical ganglion or fetal locus coeruleus grafts
- 1994
-
Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 130:2, s. 351-361
-
Tidskriftsartikel (refereegranskat)abstract
- Solid pieces of fetal locus coeruleus (LC) or superior cervical ganglion (SCG) were placed into a fimbria-fornix lesion cavity in 6-hydroxydopamine-treated, noradrenaline (NA)-denervated rats. Six to 8 months later, all animals were subjected to electrical kindling stimulations in the hippocampus until they had reached the fully kindled state. Nongrafted lesioned animals showed markedly increased kindling rate which was partly attenuated by LC but not SCG grafts. In both LC- and SCG-grafted animals, dopamine beta-hydroxylase immunocytochemistry demonstrated a high density of graft-derived noradrenergic fibers in the dorsal hippocampus, whereas reinnervation of the ventral hippocampus was much more sparse. Subregional distribution of these fibers within the hippocampus was different in the two grafted groups. Both grafts partly restored basal extracellular NA levels in the hippocampus and reacted to generalized seizures by a significant (two- to threefold) increase of NA release, as measured by intracerebral microdialysis. Our data indicate (i) that seizure activity can regulate transmitter release from noradrenergic neurons in both LC and SCG grafts, (ii) that only fetal LC grafts retard seizure development in kindling, and (iii) that the inability of SCG implants to influence kindling epileptogenesis could be due to a lack of synaptic contacts between the graft-derived ganglionic fibers and host hippocampal neurons.
|
|
| 5. |
- Lindvall, Olle, et al.
(författare)
-
Grafts in models of epilepsy
- 1994
-
Ingår i: Functional Neural Transplantation. - 078170068X ; , s. 387-387
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
| 6. |
- Mandel, Ronald J., et al.
(författare)
-
The Importance of Graft Placement and Task Complexity for Transplant-Induced Recovery of Simple and Complex Sensorimotor Deficits in Dopamine Denervated Rats
- 1990
-
Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 2:10, s. 888-894
-
Tidskriftsartikel (refereegranskat)abstract
- The present study examined the role of graft placement and behavioural task complexity in determining the functional efficacy of intrastriatal grafts of dopamine-rich fetal ventral mesencephalon (VM) placed in the dopamine (DA) depleted striatum. The functional effects of two different striatal placements of VM grafts were evaluated using tests of drug-induced motor asymmetry, simple sensorimotor orienting response, and a more complex sensorimotor integrative task (disengage behaviour), in which the rat has to perform the orienting response while in the act of eating. Rats with complete unilateral 6-hydroxydopamine (6-OHDA) lesions of the mesostriatal DA pathway, received either implants of dissociated fetal VM in the central or ventrolateral portions of the denervated striatum. Nongrafted lesioned rats served as controls. Nine weeks after grafting, the rats were tested on separate days for disengage behaviour, sensorimotor orientation, and amphetamine-induced rotational behaviour. Consistent with previous findings, the two graft placements had differential effects on drug-induced motor asymmetry and sensorimotor responses: the centrally placed VM grafts reversed amphetamine-induced rotational asymmetry but had little effect on the sensorimotor deficit, whereas the ventrolaterally placed grafts reversed the sensorimotor orientation deficits without any effect on the drug-induced rotation. In contrast, fetal VM grafts, regardless of their placement, did not ameliorate the observed deficits in disengage behaviour; that is the grafted rats that had recovered their sensorimotor response in the absence of food were unable to perform the same orienting response while eating. These results provide evidence that functional intrastriatal VM grafts which are capable of restoring sensorimotor responses or motor asymmetry fail to affect lesion-induced deficits in a task that requires more complex sensorimotor integration. It is suggested that the degree of anatomical integration of the grafted DA neurons into the host circuitry will determine the efficacy of the grafts to influence more complex sensorimotor integrative deficits in the DA lesion model.
|
|
