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The main center for the control of sexual functions is located in the hypothalamus. The medical preoptic area and the mediobasal hypothalamus are sites of production of neuropeptides which are released into the hypothalamo-pituitary portal vessel system and which function as releasing and inhibiting hormones.

1. EEG (occipito-central, anterior and posterior temporo-central), blood concentration of hormones (oestradiol, progesterone, prolactin, folliculo-stimulating (FSH) and luteinizing (LH) hormones) and psychometric tests (reaction time, concentration, simple calculations, visual orientation and simple motor performance tasks) were recorded from 16 young women during a spontaneous menstrual cycle (s.c.w. group) and from 16 women taking combined oral contraceptives (o.c.w. group). All data were collected every second day except Sundays. 2. The EEGs underwent power spectrum analysis. Power and weighted mean frequency were determined for different frequency bands (theta, alpha and beta). The most constant finding in the s.c.w. group was a slight increase of mean alpha frequency during the luteal phase until menstruation (mean of occipital alpha acceleration = +0.3c/sec). The average time course of this acceleration fitted the time course of progesterone increase, but no direct correlation could be established. No such acceleration of alpha frequency could be found in the o.c.w. group, but the mean frequency in this group was about 0.5c/secslower than that of the s.c.w. group. In addition, minor cyclic changes of EEG paramenters in the s.c.w. group were observed in the occipital and temporal theta activity, the temporal alpha activity, but none in the beta range. 3. Reaction times to simple tasks, simple arithmetic, etc. were slightly but significantly decreased in the s.c.w. group during the luteal phase with a minimum on the day before or during menstruation. No such changes were observed in the o.c.w. group, which performed, in all tasks, slightly slower and slightly less correctly than the s.c.w. group. 4. The individual relative accelerations of alpha frequency and shortening of reaction times were positively correlated with each other.

By means of microelectrodes action potentials of single optic nerve fibers from on-center neurons of the cat's retina were recorded. The latency of the inhibition of the neuronal activity elicited by light stimuli in the inhibitory receptive field periphery was measured. The inhibiting light stimuli (rings or bars) were projected into different parts of the receptive field periphery. From the spatial separations of the inhibiting light stimuli and the differences of the corresponding inhibition latencies the conduction velocity of lateral inhibition within the receptive field was measured. A value of 90–110 mm · sec−1 in the retina was found, which corresponds to about 400–480 degrees · sec−1 in the visual field.

The 105 kDa extracellular domain of c-erbB-2 encoded protein p185 is detectable in serum. Elevated p105 serum levels were found in patients with breast and ovarian cancer and in pregnancy. The effects of interfering and influencing factors on the measurement are still unclear.We used an ELISA based on the monoclonal capture antibody OD-3 and investigated possible interfering factors, like changing transporting and storing conditions of blood and serum samples. In order to evaluate a normal range of p105 serum values we examined 71 healthy women.In our tests we found no influence on the reproducibility of results by changing transporting and storing conditions. We could not find any dependency of p105 serum values on the menstrual cycle or the age of controls. Postmenopausal women showed significantly higher serum values than premenopausal women (p = 0.0127).Clinical interpretation of female p105 serum values requires comparison with normal ranges when considering the menopause as an influencing factor.

In breast and ovarian cancer patients elevated serum levels of the oncoprotein p105 were detected. We examined the influence of endocrine factors on the p105 serum concentration.The sera of 115 and non-pregnant women were analysed. Of the premenopausal women (n = 77) hormonal contraception was used by 30 women, and of the postmenopausal women (n = 33) there were 15 women using hormonal replacement therapy (HRT). The serum specimens were analysed by ELISA.Women with hormonal contraception had significantly lower serum levels than premenospausal controls (82-138 fmol/ml, median 109 fmol/ml vs. 103-183 fmol/ml, median 130 fmol/ml; P0.001). In postmenopausal women with HRT serum levels were significantly lower than in postmenopausal controls (88-136 fmol/ml, median 117 fmol/ml vs. 99-261 fmol/ml, median 148 fmol/ml; P0.001).Sex steroids seem to modulate c-erbB-2 activity. These results are important with regard to clinical studies on p105 oncoprotein in cancer patients.