Biomedical subjects

M Poltorak

Publications and source records attributed to M Poltorak.

41 records · Page 3Linked to original sources

PubMedDate not supplied

Changes in L1 antigen expression in the rat striatum after substantia nigra lesions.

L1 antigen promotes neurite outgrowth from dopaminergic neurons in tissue culture. In the present study, we examined the effects of dopaminergic deafferentation of the striatum on L1 expression. In the medial-periventricular part of the striatum, both complete and partial substantia nigra (SN) lesions decreased L1 expression. Complete lesions increased L1 expression in the dorso-medial and ventro-lateral parts of the striatum on the lesioned side when compared with that on the non-lesioned side. The decrease in the ventro-lateral area was maintained in animals examined three months after the lesioning. Animals with partial SN lesions showed a different pattern of altered L1 expression. After frontal cortex lesions, changes in L1 expression also occur preferentially in the dorso-medial and periventricular striatum. Therefore, the results indicate a complex regulation of L1 expression after damage of striatal circuitry, manifested by a preferential occurrence of changes in periventricular regions.

Animals↗

PubMedDate not supplied

Intracerebroventricularly transplanted embryonic neuronal tissue from inflammatory-resistant F344/N rats decreases acoustic startle responses in inflammatory-susceptible LEW/N rats.

Recently, we have shown that intracerebral transplantation of fetal F344/N hypothalamic tissue into LEW/N rats converts the LEW/N inflammatory-susceptible phenotype into an inflammatory-resistant phenotype in LEW/N hosts. Because LEW/N rats also exhibit relatively high acoustic startle responses (ASRs) compared to F344/N rats, in the present study we examined the effects on ASR of transplantation of F344/N hypothalamic tissue into the third ventricle of LEW/N rats. Dissected neuronal tissue from F344/N rats (Day E15-16) was implanted into the third ventricle of LEW/N rats. After 4 wk of postoperative survival, the animals' responses to acoustic startle stimuli were tested. Compared to naive and sham-operated animals, LEW/N rats transplanted with hypothalamic tissue exhibited significant decreases in ASR amplitudes. A similar decrease in ASR amplitude was observed in the group of LEW/N rats transplanted with embryonic striatal tissue. Our results indicate that the third ventricular neuronal grafts may modulate behavioral responses in the LEW/N rats. Although the mechanism of this effect is unknown, these studies suggest that intracerebral neuronal transplantation is a viable method with which to explore mechanisms of behavioral, neuroendocrine, and inflammatory response associations.

Acoustic Stimulation↗

PubMedDate not supplied

Constitutive expression of glutamic acid decarboxylase (GAD) by striatal cell lines immortalized using the tsA58 allele of the SV40 large T antigen.

Rodent striatal cells were immortalized using the A58 temperature-sensitive allele of the SV40 large T antigen. Seventy-eight clones and 10 mixed cultures were characterized at the nonpermissive and permissive temperatures. Based on morphology and expression of proteins, cells were classified into three primary types, with types b and c expressing some neuronal characteristics. Type a cells have an epithelial-like morphology with coarse cytoplasmic extensions and occasional fine processes. These cells express vimentin, do not grow well under serum-free conditions and, when confluent, form a uniform monolayer. Type b cells have a polygonal shape and usually extend multiple thin processes. These cells possess large nuclei with multiple nucleoli and do not express vimentin. Type c cells have a fibroblast-like appearance, are unipolar or multipolar, and their soma is smaller than that of type b cells. Type c cells do not express vimentin, and when confluent form a uniform monolayer. Some type b and c clones express N-CAM and MAP-2. Several type b and c cell lines were found to consistently express glutamic acid decarboxylase (GAD) immunoreactivity under several tissue culture conditions. Selected cell lines were transplanted into the intact adult rat brain in several locations. Cells survived well for 15 wk and did not form tumors. The proteins expressed in vivo were similar to those expressed in vitro.

Alleles↗

PubMedDate not supplied

The degree of genetic disparity between donor and host correlates with survival of intraventricular substantia nigra grafts.

We have evaluated the degree of genetic disparity that permits survival of intraventricular brain tissue grafts without additional immunosuppression. Fisher 344 rats (n = 100) with unilateral substantia nigra lesions were used as hosts. Donors consisted of Fischer 344 rats (isografts), Sprague-Dawley rats (allografts), mice, hamsters, and rabbits (xenografts). Grafts were obtained from the ventral mesencephalon of embryonic animals. The functional properties of the grafts were measured by behavioral rotation tests. Frequency of graft survival determined histologically was related to the degree of genetic disparity between donor and host. In comparing rabbit and hamster xenografts, the greater degree of disparity for the rabbit-to-rat grafts was associated with a shorter period of behavioral recovery (3 weeks vs. 5 to 6 weeks) after transplantation. It is concluded that rejection of intracerebral brain tissue grafts does not occur as an all-or-none process, but instead varies as a function of the degree of genetic disparity between donor and host.

Animals↗

PubMedDate not supplied

Intraventricular xenografts: chronic injection of antibodies into the CSF provokes granulomatosis reactions but Ia antibodies do not enhance graft survival.

We have studied the influence of chronic infusions of antibodies against Ia antigen into the CSF on immunological reactions to intraventricular xenografts in rats. The antibodies were infused with osmotic pumps implanted one day before grafting. One set of control groups consisted of animals with xenografts which simultaneously received antibody against penicillin or vehicle with no antibody. In a second set of control groups, antibodies against Ia antigen, penicillin, rat anti-mouse IgG or vehicle (no antibody) were administered alone, without grafts. In the animals that received infusions of antibodies against either Ia antigen or penicillin plus xenografts, intense granulomatosis reactions were observed in the host brains. These reactions were not observed in the animals that received antibody infusions without xenografts. It appears that this reaction was produced by the massive and persistent injection of immunoglobulins, together with the presence of xenograft tissue. The chronic infusion of Ia antibodies did not prolong xenograft survival.

Animals↗