Molecular Alterations in Nerve Cells: Direct Manipulation and Physiological Mediation. In: Imura H, editor. Recombinant DNA Technologies in Neuroendocrinology. Berlin: Springer Berlin Heidelberg; 1993. pp. 169-91. [DOI: 10.1007/978-3-642-77503-1_7]

Actions of sex steroids on behaviours beyond reproductive reflexes

The actions of sex steroids in the brain have been shown, from molecular to systems levels, to control reproductive behaviour in a wide range of vertebrates. It has become increasingly clear that gonadal steroid hormones have regulatory functions which extend far beyond the direct coordination of an animal's physiological state and its display of sexual behaviour. While some of these actions may include changes in mood or other behavioural measures, such as exploration or excitability, sex steroid hormones also influence neural plasticity, neuronal activity and, possibly, learning and memory, as reflected by long-term potentiation or age-related deficits. Here we describe two systems that have been used to explore the non-reproductive roles of gonadal steroid hormones. The first of these is to examine the oestrogen-sensitive opioid peptide gene expression in the hypothalamus. Currently, we are attempting to identify the types of behaviour which may be altered consequent to the oestrogenic induction of the preproenkephalin gene. The second approach involves studying the effects of progesterone at the neuronal cell membrane and characterizing the metabolites of progesterone which have benzodiazepine-like actions in the brain. A number of studies suggest that this may provide an alternative mechanism through which progesterone can influence mood or behaviour.

Gene transfer and in vivo promoter analysis of the rat progesterone receptor using a herpes simplex virus viral vector

The progesterone receptor (PR) gene is expressed in cells of the anterior pituitary and hypothalamus, and PR levels are regulated by estrogen (E) in a tissue-specific fashion. To demonstrate that E induces transcription via the PR promoter, and to identify sequences within the PR promoter responsible for tissue-specific and hormonal regulation, we have utilized a defective herpes simplex virus vector for direct gene transfer into the rat pituitary and brain. We designed a viral amplicon expressing the beta-galactosidase gene under the regulation of a 2.1-kb PR promoter fragment to create a defective viral vector for gene transfer into the brain. Following injection of this vector into the pituitary and brain, its pattern of expression and ability to respond to estradiol 3-benzoate (EB) were examined. In the pituitary, lacZ activity was observed in cells of the anterior lobe (AL). However, no activity was seen in the neurointermediate lobe (NIL), demonstrating tissue specific transcriptional regulation. A approximately sixfold increase in cells demonstrating beta-galactosidase activity was observed in the AL following treatment with EB. Likewise, injection of defective viral vector into the hypothalamus followed by treatment with EB resulted in a approximately eightfold increase in cells demonstrating beta-galactosidase activity including the very cell groups responsible for EB-dependent reproductive behavior. In contrast, no vector dependent activity was observed in the caudate nucleus, a tissue with no endogenous expression of PR, despite polymerase chain reaction evidence demonstrating the presence of the vector in this tissue. These results demonstrate that the 2.1-kb PR promoter fragment contains the sequence information required for correct tissue and hormonal regulation of PR.

Application of antisense DNA method for the study of molecular bases of brain function and behavior

The antisense DNA method has been used successfully not only in vitro but also with in vivo systems to block effectively the expression of specific genes. An increasing number of studies have shown that antisense DNA administered directly into the brain can modify various kinds of behaviors. These findings strongly suggest that the antisense DNA method can be widely used as a powerful tool for the study of the molecular bases of behavior. In addition to traditional methods of behavioral genetics, the antisense DNA method may provide a new approach for the study of the effects of gene in behavioral function. In this article, we review recent studies reporting in vivo effects of antisense DNA on brain function and behavior.