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The short-term effects of administering testosterone propionate (TP) to 4-day female rats (androgenized females) on the synthesis of specific brain proteins were investigated. At various times after the intraperitoneal injection of TP or arachis oil, [35S]methionine was injected into the third ventricle and 1 h later proteins were extracted from the hypothalamus-preoptic area (H-POA) and analyzed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Changes in synthesis of two 13,000-14,000 mol. wt. proteins in the 4-day rat brain were detected, and these changes appeared to be specific for the H-POA. In addition, silver staining revealed a 50,000 mol. wt. protein which was present in the male and androgenized female H-POA but not in the oil-treated female H-POA. An incidental, but potentially important finding, was the synthesis of a 77,600 mol. wt. protein in the H-POA of one animal which had several seizures during the experiment. These results show that changes in the synthesis of specific proteins occur in the H-POA of neonatal female rats within 8 h of TP administration and support the hypothesis that hormone-induced changes in brain protein synthesis may be involved in sexual differentiation of the brain.

We have investigated the changes in the concentrations of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in the hypothalamus-preoptic area (HPOA) and midbrain raphe (MR) region of male and female rats throughout development. No sex differences were found in the concentrations of the indoleamines in either of the areas investigated at any stage of development. The 5-HIAA/5-HT molar ratio was maximal at 4 days of age in both the HPOA and MR. A small but significant sex difference in the 5-HIAA/5-HT ratio occurred in the HPOA (higher in males) but not in the MR at 40 days of age, and the ratio was significantly greater in 80-day-old female rats in the HPOA but not MR. Studies using NSD 1015 to block the conversion of 5-hydroxytryptophan to 5-HT showed that a higher rate of 5-HT synthesis occurred in the HPOA of 80-day-old rats compared with the neonatal HPOA and that in 80-day-old rats the rate of 5-HT synthesis was significantly higher in females. These results show that endogenous steroids do not affect the activity of serotoninergic neurons in the HPOA or MR either during or immediately after the critical period of sexual differentiation. In addition, the results from the NSD 1015 experiments show that the high 5-HIAA/5-HT ratio found in neonates does not involve a higher rate of 5-HT synthesis than that in adult rats.

To investigate possible sex differences in central catecholaminergic systems, the concentrations of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were measured by high-performance liquid chromatography with electrochemical detection in the hypothalamus-preoptic area (H-POA) and midbrain raphe (MR) region of male and female rats throughout postnatal development. Other than a small but significant sex difference in DA concentration in the MR at 36 h (higher in females), the results showed that there were no sex differences in the concentrations of DA or DOPAC at any age in either brain region. The developmental profiles of the concentrations of DA and DOPAC showed that DAergic systems in the H-POA are immature at birth, with concentrations increasing steadily until 80 days of age, but in the MR concentrations reach a maximum at 20 days of age; a situation which is perhaps a reflection of differing monoamine metabolism in the two areas.

The study examined how a project based on the research process was included in ENB Course 100 and how effective this method was in teaching course members about nursing research. The data was collected by a postal questionnaire to course teachers and by pre- and post-project questionnaires to 12 course members taught by the investigator. Most course teachers include a project in their programme and felt this met the research objective required by the ENB. Advantages of the method described were improved problem-solving skills, awareness and understanding of research and implications arising for clinical practice. Disadvantages include limitations of time, quality, ethical considerations and selecting suitable topic areas. The course members had received little instruction on nursing research prior to the course, but their attitudes to it were positive. Following the project, they described the practical experience of data collection and analysis as the most enjoyable aspects, and the least enjoyable as interpretation and writing up of results. Attitudes to nursing research had improved or remained positive from the experience of the project method. It was recommended that the project be considered as a method of teaching nursing research in this post-basic course.

Sex differences in brain protein synthesis were investigated by analyzing the in vitro translation products of poly (A)+ mRNA isolated from the hypothalamus-preoptic area of male, female and androgenized female (injected with testosterone propionate at day 4) rats at different stages of development. Poly (A)+-enriched mRNA, prepared by oligo (dT)-chromatography of total RNA extracted by guanidine thiocyanate, was translated in either a rabbit reticulocyte lysate or cell-free wheat germ system supplemented with either [35S]methionine or a [3H]amino acid mix. The translation products were analyzed by one- and two-dimensional SDS-PAGE. Several developmental and androgen-induced changes were found in the translation products of specific mRNA species, the most important of which was a sex difference (higher in the male) in the apparent amount of mRNA coding for proteins with the electrophoretic characteristics of actin and tubulin. These developmental and sex differences in the apparent amounts of specific mRNA species in brain may be the cause or result of functional and structural changes such as neurite growth and synapse formation.

Subcellular fractions were prepared from the hypothalamus-preoptic area and the ‘remainder of the brain’ of intact male and female rats at 0, 8, 25 and 72 days of age. Proteins associated with each fraction were subjected to SDS-PAGE chromatography and stained with Coomassie Brilliant Blue. Developmental changes were found to occur in proteins associated with the soluble (14, 600, 15, 000, 29, 900, 38, 900 and 49, 000 mol. wt), nuclear (40, 000–50, 000 and 13, 800–16, 000 mol. wt.), mitochondrial-lysosomal (49, 000–52, 000 mol. wt.) and microsomal (14, 400, 20, 000, 50, 100, 56, 900 and 130, 000 mol. wt.) fractions. In addition, soluble proteins were greater in males than in females at days 0 (53, 000–56, 000 mol. wt.; probably tubulin) and 25 (14, 600 and 15, 000 mol. wt.). These changes in brain proteins probably reflect important structural and functional changes that occur during maturation and sexual differentiation of the brain.