Interaction between recovery from behavioral asymmetries induced by hemivibrissotomy in the rat and the effects of apomorphine and amphetamine.

Spontaneous and drug-induced turning behavior and thigmotactic scanning were tested either acutely (4-6 hr) or chronically (9 days) after unilateral removal of vibrissae in rats. Rats that were tested acutely scanned more with the intact vibrissae side. This asymmetry was reduced in rats that were tested chronically, indicating behavioral recovery. The indirect dopamine agonist amphetamine induced a reversed asymmetry after 9 days because the animals then scanned more with the side lacking the vibrissae. Postsynaptic doses of apomorphine administered to acutely tested rats induced more scanning with, and more turning toward, the intact vibrissae side. A negative correlation was found in the chronically tested rats between the asymmetry in spontaneous scanning and the asymmetry after apomorphine. Nonrecovered rats showed indications of a reversal after apomorphine. The results are discussed in relation to mechanisms of neural plasticity in the basal ganglia, such as receptor supersensitivity and changes in nigrostriatal afferents.

Inhibition of proliferation and induction of differentiation of pluripotent human embryonal carcinoma cells by osteogenic protein-1 (or bone morphogenetic protein-7).

BACKGROUND: Osteogenic protein-1 (OP-1) is a member of the transforming growth factor-beta super family closely related to the bone morphogenetic proteins and also known as bone morphogenetic protein-7. Other members of this family of growth factors influence cell differentiation as well as cell growth in a number of systems. The Drosophila homolog encoded by the decapentaplegic locus is involved in dorsal-ventral pattern formation during embryogenesis, whereas the expression of several bone morphogenetic proteins including OP-1 is developmentally regulated in mammalian embryos. EXPERIMENTAL DESIGN: The effect of recombinant human OP-1 on the proliferation and differentiation of an established pluripotent human embryonal carcinoma (EC) cell line, NTERA2, and three nullipotent human EC cell lines, 2102Ep, 833KE and TERA-1, was investigated. These cells were grown under reduced serum conditions, and differentiation was monitored by morphology and expression of marker antigens. RESULTS: OP-1 inhibited proliferation of NTERA2 and induced their differentiation, marked by changes in cellular morphology, the loss of EC cell antigens (SSEA3, SSEA4, the liver isozyme of alkaline phosphatase), and the appearance of new antigens, notably SSEA1 and class 1 major histocompatibility complex antigens. These changes were irreversible and did not involve significant cell degeneration or cell death. The OP-1-induced differentiation of NTERA2 appeared distinct from that induced by either retinoic acid or hexamethylene bisacetamide. Nevertheless, OP-1 did induce the homeobox gene, HOXA1. By contrast, OP-1 elicited only a limited and partial response from the nullipotent EC cell lines. CONCLUSIONS: Our results suggest that pluripotent human EC cells differentiate in response to OP-1 and that this factor can modulate the differentiation induced by retinoic acid. Like other members of the transforming growth factor-beta super family, OP-1 might play an inductive role in the early embryo. The results also suggest a possible therapeutic value for OP-1 in the treatment of some germ cell tumors.

Regulation of intracellular Ca2+ in response to muscarinic and glutamate receptor agonists during the differentiation of NTERA2 human embryonal carcinoma cells into neurons.

Single cell microfluorimetry was used to study intracellular calcium ion signals ([Ca(2+)](i)) evoked by acetylcholine (ACh), glutamate receptor agonists and by KCI-induced membrane depolarization, during neuronal differentiation of the human embryonal carcinoma (EC) cell line, NTERA2. In undifferentiated NTERA2 EC cells, [Ca(2+)](i) was elevated in response to ACh, but not to the glutamate receptor agonists NMDA, kainate or AMPA. The ACh-induced rise in [Ca(2+)](i) was dependent upon both Ca(2+) influx and Ca(2+) mobilization from cytoplasmic calcium stores. Three other human EC cell lines responded similarly to ACh but not to glutamate or KCI-induced depolarization. In neurons derived from NTERA2 cells by retinoic acid induction, [Ca(2+)](i) signals were evoked by ACh, NMDA, kainate and by an elevation of the extracellular KCI concentration. As in undifferentiated EC cells, the ACh-mediated increases in [Ca(2+)](i) were governed by both Ca(2+) influx and Ca(2+) mobilization. In contrast, the effects of NMDA, kainate and KCI did not involve intracellular Ca(2+) mobilization. The appearance of glutamate and KCI responsiveness was not detected in non-neuronal differentiated derivatives of NTERA2 cells. Using a number of pharmacologically defined muscarinic receptor antagonists we found that NTERA2 EC cells express M(1), M(3), M(4) and possibly M(5) receptor subtypes linked to changes in [Ca(2+)](i), whilst only M(3) and M(5) are present in NTERA2-derived neurons. The results were supported by PCR analysis of the muscarinic mRNA species expressed in the cells. The data demonstrate that differentiation of NTERA2 EC cells into neurons involves the induction of functional glutamate receptors coupled to rises in [Ca(2+)](i), and changes in the expression of muscarinic ACh receptor subtypes.