Effects of prolactin on expression of the mRNAs encoding the immediate early genes zif/268 (NGF1-A), nur/77 (NGF1-B), c- fos and c- jun in the hypothalamus

• Published in: Brain research. Molecular brain research. Vol. 61; no. 1; pp. 62 - 68
• Main Authors: Sagrillo, Cathleen A., Selmanoff, Michael
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 30.10.1998; Elsevier
• Subjects: Animals; Autofeedback; Biological and medical sciences; DNA-Binding Proteins - biosynthesis; DNA-Binding Proteins - genetics; Early Growth Response Protein 1; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - drug effects; Genes, fos - drug effects; Genes, fos - genetics; Genes, Immediate-Early - drug effects; Genes, jun - drug effects; Genes, jun - genetics; Hormones and neuropeptides. Regulation; Hypothalamus; Hypothalamus - chemistry; Hypothalamus - drug effects; Hypothalamus. Hypophysis. Epiphysis. Urophysis; Immediate early gene; Immediate-Early Proteins; In Situ Hybridization; Injections, Subcutaneous; Male; Nerve Tissue Proteins - genetics; Neurons - chemistry; Neurons - drug effects; Neuropeptides - genetics; Prolactin; Prolactin - administration & dosage; Prolactin - pharmacology; Rats; Rats, Sprague-Dawley; RNA, Messenger - analysis; RNA, Messenger - biosynthesis; RNA, Messenger - drug effects; Transcription Factors - biosynthesis; Transcription Factors - genetics; Vertebrates: endocrinology; Zinc Fingers; Hypothalamus; Prolactin; Autofeedback; Immediate early gene; Vertebrata; Mammalia; Adenohypophyseal hormone; Rat; Rodentia; Gene expression; Protooncogene
• ISSN: 0169-328X; 1872-6941
• DOI: 10.1016/S0169-328X(98)00198-3

Prolactin (PRL) exerts a short-loop negative feedback effect on hypothalamic neurons which control its secretion from the anterior pituitary gland. The purpose of this study was to identify the location of hypothalamic neurons which respond to acute PRL exposure. Increasing evidence indicates that excitation of neurons often results in the rapid transcription of immediate early genes (IEGs). In the present study, quantitative in situ hybridization histochemistry (ISHH) was used to visualize the induction of mRNAs for four different IEGs: zif/268 (NGF1-A), nur/77 (NGF1-B), c- fos and c- jun. Three groups of male rats were compared: unmanipulated controls, rats injected s.c. with 2.4 mg ovine PRL (oPRL) suspended in polyvinylpyrrolidone (PVP), and PVP-injected controls. Animals were decapitated 0, 0.5, 1, 2, 3 or 4 h following injection. In all rats, the four probes labeled cells within the cortex, particularly the cingulate and piriform cortices, the hippocampus and the striatum. In the arcuate nucleus, there was a modest increase in the average number of cells/animal which expressed zif/268 mRNA following the injection of PVP and oPRL at all times studied. The average area of grains/cell representing zif/268 message also increased following the injection stimulus. The number of neurons expressing nur/77 mRNA was greater in PRL-treated rats compared with PVP-treated controls 0.5 and 1 h following injection. Nur/77-labeled neurons were co-extensive with the tuberoinfundibular dopaminergic (TIDA) neurons. The data suggest that cells located within the arcuate nucleus are involved in mediating PRL autofeedback on the brain.