Purkinje cells appearance

Pilpel and Segal, 2004). This spine phenotype was also observed in transgenic mice expressing CA Racl in Purkinje cells (Luo et al., 1996). Such spines appear to be often engaged in multiple synaptic contacts, which is rarely seen in normal animals (Luo et al., 1996). On the other hand, expression of a DN Racl... 

In slices of rat cerebellum, LTD of parallel fibre inputs to Purkinje cells can be induced by pairing low-frequency stimulation (1 Hz for 5 min) with post-synaptic depolarisation. Both WIN55, 212-2 (1 pM) and CP55,940 (400 nM) reduced the EPSC by about 50%, and impaired the induction of LTD, an effect which was blocked by rimonabant (1 pM) (Levenes et al. 1998). In this pathway, therefore, it appears that cannabinoid effects on synaptic plasticity may be secondary to changes in baseline responses. 

In the cerebellar cortex, the most frequently noted pathology is a decreased number of Purkinje cells (Kemper and Bauman, 1998 Palmen et al., 2004 Bauman and Kemper, 2005 Whitney et al., 2008). This pathology is most marked in the posterior lateral part of the cerebellar hemispheres and the adjacent archicerebellar cortex and occurs without evidence of loss of neurons in the inferior olive in the brain stem (Kemper and Bauman, 1998 Bauman and Kemper, 2005). The Purkinje cells have an intimate relationship with the axons of the inferior olivary neurons in the brain stem, such that loss of Purkinje cells at any time after birth leads to loss of neurons in the inferior olive (Holmes and Stewart, 1908 Norman, 1940 Sakai et al., 1994). Since this intimate relationship between the Purkinje cell and the inferior olive is established in the human brain sometime after 29-30 weeks of gestation (Rakic and Sidman, 1970), it is likely that the decrease in number of Purkinje cells occurred before this time. In those brains with a marked decrease in the number of Purkinje cells, there appears to be a concomitant decrease in the number of granule cells (Bauman and Kemper, 2005). The relationship between the number of granule cells and the number of Purkinje cells noted in the autistic brain has been elucidated in rat studies. With prenatal loss of Purkinje cells the number of granule cells is adjusted such that the ratio of Purkinje cells to the number of granule cells is maintained (Chen and Hilman, 1989). 

Soluble guanylate cyclase is activated by nitric oxide (NO) (see Section 3.4). NO has been implicated in the generation of long term depression (LTD) of parallel fiber-mediated EPSP s in Purkinje cells. LTD can be prevented by the application of haemoglobin that absorbs NO, or by the inhibition of NO synthesis (Crepel and Jaillard, 1990 Shibuki and Okada, 1991 Ito, 1991). However, nitric oxide synthase, the synthesizing enzyme of NO, appears to be absent from the Purkinje cell (Section 3.4.). 

Fig. 30. A. Frontal section through the cerebellum and attached brainstem of an adult rat. All the Purkinje cells are stained by cyclic 3, 5 -guanosine monophosphate-dependent protein kinase (cGK) antiserum, including their dendrites in the molecular layer and their axon terminals in the deep nuclei and in the brainstem (arrow). Bar = 1 mm. B. Higher magnification of the neurons indicated by an arrow head in A. Like a few other isolated labelled cells found in variable locations, these cells are considered as ectopic Purkinje cells. Bar = 50 /tm. C. cGK immunoreactive neuron in the cerebellum of I day-old rat. This ectopic Purkinje cell is located in the white matter and its appearance mimics that of 1-day-old Purkinje cells as visualized in Golgi impregnated material. Bar = 25 /tm. Wassef and Sotelo (1984).

L-7 is a protein specific for Purkinje cells. Labelling with polyclonal antibodies against predicted L-7 sequences was present in somata, including the nucleus, in dendrites and dendritic spines, and in axon and axon terminals of Purkinje cells. All Purkinje cells, but no other types of cerebellar neurons appeared to be labelled (Berrebi and Mugnaini,... 

The large ealiber fibers within the compartments of the white matter could be identified as Purkinje cell axons with axonal tracing methods and immunohistochemistry with Purkinje cell-specific antibodies. They appear as discrete bundles, separated by narrow gaps with antibodies against cyelic GMP-dependent protein kinase (De Camilli et al.,... 

---