Expression of carbonic anhydrase II gene in early brain cells as revealed by in situ hybridization and immunohistochemistry

Neuronal localization of 5-HT1A receptor mRNA and protein in rat embryonic brain stem cultures

The aim of the present work was to study the cellular localization of 5-HT1A receptor protein and mRNA in rat embryonic brain cultures. Primary cultures of the whole brain from rat fetuses at embryonic day (ED) 12 and of the brain stem at ED 14-ED 16 were stained with specific anti-5-HT1A receptor antibodies or a 40-mer biotin-labelled deoxyoligonucleotide complementary to the 5-HT1A receptor mRNA. The use of a biotinylated probe allowed the morphology of the cells to be preserved. 5-HT1A receptor mRNA was already detected in primary cultures from the brain of ED 12 embryos whereas the receptor protein first appeared two days later, at ED 14. Both 5-HT1A receptor mRNA and protein were found within neuron-like cells (labelled with antibodies against neuron specific enolase, microtubule-associated protein 2 or aromatic L-amino acid decarboxylase) but not in glial cells (specifically labelled with antibodies against glial fibrillary acidic protein, myelin basic protein or carbonic anhydrase II). Double staining with the 5-HT1A receptor mRNA probe and anti-5-HT antibodies suggests that 5-HT1A (auto)receptors are expressed by serotoninergic neurons during early ontogenesis.

Primary culture of postnatal rat hypothalamic neurons in astrocyte-conditioned medium

Mature functional hypothalamic neurons of male and female rats (21-day postnatal) were successfully cultured without attachment to non-neuronal cells in serum-free astrocyte-conditioned medium (ACM). A novel cell-collecting method was designed for these vulnerable cells by allowing the dissociated cell suspension to stand in a vertically held, wide-tipped syringe so that the cells were concentrated near the lower liquid surface, from which position they could be easily dropped into the medium, leaving most of the small debris in the syringe. This method made it possible to study statistically the survival of cultured neurons. It was impossible to collect many viable cells by the commonly used dissociating technique for fetal rat brain. However, neuron-like cells with a few processes could be isolated from sliced hypothalamic tissues by means of enzymatic and mechanical treatments. The original processes disappeared within 1-2 days and some new processes were generated after 2-3 days in vitro; the cells survived for 28 days in vitro. The cells were identified as neurons by the immunostaining method for microtubule-associated protein 2 (MAP2) and neurofilament (NF). Such neurons were obtained from every site of hypothalamic tissue sampled. These phenomena were not observed in chemically-defined medium (CDM), CDM supplemented with basic fibroblast growth factor (bFGF), epidermal growth factor (EGF) or nerve growth factor (NGF).

Double-labeling in situ hybridization analysis of mRNAs for carbonic anhydrase II and myelin basic protein: expression in developing cultured glial cells

We applied in situ hybridization to analyze the location and the developmental changes in the distribution of the transcripts for carbonic anhydrase II (CAII) and myelin basic protein (MBP) in mouse primary cultured glial cells. Both mRNAs were localized to the oligodendrocyte using double-labeling in situ hybridization. No evidence for CAII transcripts in astrocytes was obtained, indicating that CAII is expressed only by oligodendrocytes in normal rodent glia. As early as 48 h after plating, CAII and MBP mRNAs are present in a few, small round cells. Message is present 2-4 days before levels of these proteins can be detected in similar primary glial cultures. The intensity of labeling for MBP and CAII mRNA positive cells increases significantly during the second week but then decreases after the end of the third week. Only the oligodendrocyte perikaryon and a few processes are positive during the first week. In contrast, at 14 days, a large number of cell processes in addition to the cell bodies are heavily stained for both mRNAs. Both mRNAs could be detected far away from the cell body, up to 250 microns in some cell processes. Some segments on a cell process accumulate higher levels of mRNA than other areas. These areas may correspond to the accumulation of free ribosomes and to starting points for the membrane sheets elaborated by cultured oligodendrocytes. The developmental profile for timing and distribution of these two messages mimics closely their in situ pattern.

Cellular and molecular aspects of the renal effects of diuretic agents

In the past few years, increased knowledge of the nature of transport proteins and their molecular regulation in the translocation of ions across kidney membranes has emerged. We are beginning to better understand the characteristics of the interaction of diuretics with these transport proteins. It is likely that this knowledge will permit further insight into nephron function regulation.