NGF and BDNF in the anterior pituitary lobe of adult rats.

Previous studies revealed that NGF-like immunoreactivity is present in cells from the adult rat anterior pituitary lobe, both in vivo and in vitro, and that in both situations NGF colocalizes with the thyroid-stimulating hormone (TSH). More recently, brain-derived neurotrophic factor (BDNF) was similarly found to occur in the anterior pituitary tissue, again with a general colocalization with TSH. In the present study, we have extended the use of adult rat anterior pituitary cultures to show their content of BDNF-immunoreactive cells and their main colocalization with TSH. We have also explored the question of whether neurotrophins nerve growth factor (NGF) and/or BDNF are actually produced within anterior pituitary cells. Use of the sensitive method reverse transcription-polymerase chain reaction (RT-PCR) has allowed us to confirm the presence of NGF and BDNF mRNAs in the cell suspension freshly derived from adult anterior pituitary. In situ hybridization techniques applied to the cell cultures from such a suspension, however, have revealed only a variable presence of NGF mRNA-positive cells but no recognizable BDNF mRNA. Thus, the question of whether the two neurotrophins are produced within the very cells whose immunoreactive content can be recognized remains an open one.