Changes of olfactory sensitivity during the estrus cycle in female laboratory mice

In female Albino laboratory mice neural olfactory thresholdswere established by means of evoked potential measurements withpermanently implanted electrodes. The method allowed registrationof the bulbar activity up to 17 consecutive days; each day thesexual status of the animals was determined by the vaginal smears. There is a close correlation between olfactory sensitivity andestrus cycle: All individuals had their maximum olfactory acuityin proestrus; in metestrus the threshold values were up to 1million times higher. During diestrus and estrus the thresholdvalues were inbetween these extremas. This pattern was foundin the three test substances geraniol, butyric acid and butyricmethyl ester. In comparison to the olfactory thresholds in male mice, in theaverage the females had a slightly higher sensitivity in proestrus,whereas in metestrus all of them show a marked increase in theirthreshold values.     

Age-related changes in olfactory sensitivity of laboratory mice

Age-related alterations in the electrical response of olfactory epithelium to odorant-induced stimulation and certain morphometric indices were investigated in male and female laboratory mice of strains C57BL/6 (B6) and AKR (AK). It was found that maximum amplitude of response to odorants characterized young and adolescent animals. Ageing is accompanied by a decline in response level in the olfactory epithelium. Age-related distinctions between morphometric characteristics of the olfactory organ such as overall area and depth of the olfactory epithelium were noted.Applied Mathematics and Cybernetics Research Institute, N. I. Lobachevskii University, Gor'kii. Translated from Neirofiziologiya, Vol. 21, No. 6, pp. 723–729, November–December, 1989.     

Influence of nasal trigeminal stimuli on olfactory sensitivity

In the nose, the capacity to detect and react to volatile chemicals is mediated by two separate but interrelated sensory pathways, the olfactory and trigeminal systems. Because most chemosensory stimulants, at sufficient concentration, produce both olfactory and trigeminal sensations (i.e., stinging, burning or pungent), it is relevant to seek how these anatomically distinct systems could interact. This study was designed to evaluate by psychophysical measurements the modifications of the olfactory sensitivity of 20 subjects to phenyl ethyl alcohol (PEA) and butanol (BUT), after trigeminal stimulation with allyl isothiocyanate (AIC). Thresholds obtained in two separate sessions, one with and the other without previous trigeminal stimulation, were compared using a two-alternative forced-choice procedure, with a classical ascending concentrations method. The results showed that, whatever the odorant (PEA or BUT), AIC trigeminal activation produced a decrease in the olfactory thresholds, corresponding to an increase in olfactory sensitivity. These data confirm that in physiological conditions the trigeminal system modulates the activity of olfactory receptor cells but do not exclude the possibility of a central modulation of olfactory information by trigeminal stimuli. These findings are discussed in terms of methodological and physiological conditions.     

Ontogenetic development of neural responses in the olfactory bulb of laboratory mice

Summary In laboratory mice (strain NMRI) the ontogenetic development of single unit activity in the olfactory bulb was investigated. From postnatal day 10 on, spontaneously active neurons were recorded with glass-microelectrodes, and their responses to olfactory stimuli were tested (butyric acid, geraniol, grass- and nest-odour).From day 10 to 13 only very few neurons were recordable (and most of these elements were too weak and were lost before being stimulated). At day 14 the number of recordable neurons increased rapidly, and by day 15 spontaneously active neurons reached adult level in terms of incidence and electric properties.There were 3 types of neurons: 1. respiration synchronous elements; 2. bursting neurons not correlated with respiration; 3. continuously, but randomly, firing elements (about 60% of all neurons). Reactions to odour stimuli (excitation, ca. 50%; inhibition, ca. 34%; complex reactions, ca. 12%; change in activity pattern, ca. 4%) occurred as soon as the cells were stable enough for testing. The reaction patterns showed no age specific differences; the duration of the responses varied from 100 ms to 100 s.In younger animals (P11–P14) the percentage of responses was slightly smaller (47%) than in the older ones (P30–P50; 64% response to olfactory stimulation). For some of the odours tested the proportion of responding cells differed depending on age (for instance grass odour evoked a response in 40% of the cells in young ones, but in 65% in adults).Abbreviations AP action potential - In interneuron - MTc mitral or tufted cell - P10 postnatal day 10     

The influence of early odour experience on the neural response of the olfactory bulb in laboratory mice

Summary In mice (strain NMRI) the influence of olfactory rearing conditions on the ontogenetic development of the bulbar electroencephalogram (EEG) was investigated.The cages of control animals were perfused continually with filtered air, whereas in the three experimental groups geraniol was added to the atmosphere at different times (group G_0–13, from birth till day 13; group G_0–6, from birth till day 6; group G_6–12, from day 6 till day 12). At various ages the EEG of the bulbus olfactorius was studied by means of permanently implanted tungsten electrodes, and the neural response to nest odour and geraniol (10^–2 vol. %) was recorded.No differences were found between the groups regarding the overall development of the bulbar EEG, nor did the raising conditions affect the neural response to nest odour. However, in groups G_0–13 and G_6–12 a marked response to the odour of geraniol was recorded, while in the controls and the individuals that had experienced geraniol only during their first week of life, the bulbar response to this odourant did not differ from that obtained following stimulation with clean air. In the animals of group g_0–13, which were investigated as adults (day 70), the prominent geraniol response was still recordable 2 months after the last contact with the odour.These results indicate that odours experienced during a sensitive period in the nest evoke neuronal alterations in the olfactory system of the mouse that facilitate processing of a known odourant.     

美洲斑潜蝇蛹期化学环境对成虫嗅觉定向的影响

将美洲斑潜蝇Liriomyzasativae Blanchard蛹分别暴露于3种植物挥发物-芳 樟醇、β-子丁香烯和3- 己烯-1-醇,羽化后用Y形嗅觉仪测定雌成虫对相应挥发物的定向反 应。蛹期暴露于3-己烯-1-醇后羽化的雌成虫趋向该化合物的比率（37.7%）和平均反应时 间（21.5 s）,与对照组（30.4%,35.0 s）差异不显著;β-子丁香烯处理组雌成虫选择 该化合物的比率（46.2%）与对照组（42.0%）差异不显著,但平均反应时间（21.0 s）却显著短于对照组（41.5 s）。蛹期经芳樟醇处理后雌成虫选择该化合物的比率（52.9%）显著 高于对照组（28.4%）,平均反应时间（19.5 s）也显著短于对照组（34.5 s）。以芳樟醇为处理化合物的进一步研究表明,蛹发育早期是诱导成虫产生定向反应的敏感时期。将1、3、5 、7 日龄蛹分别暴露于芳樟醇48 h后,只有1日龄组蛹羽化的雌成虫趋向芳樟醇的比率（54%） 显著高于对照组（26%）;但1、3、5 日龄组蛹羽化的雌成虫对芳樟醇的平均反应时间均显著 短于对照组。此外,蛹期暴露于芳樟醇的持续时间也影响雌成虫对该化合物的定向反应,2日龄 蛹分别暴露于芳樟醇24、48、72、96和120 h后,只有处理时间大于72 h的雌成虫选择该化合物 的比率才显著高于对照组;但所有处理组羽化雌成虫的平均反应时间均显著低于对照组。由此 推断,美洲斑潜蝇蛹期经历的化学环境会影响成虫的嗅觉定向反应。     

Effect of the estrous cycle stage on sensitivity to pheromone 2,5-dimethylpyrazine in the house mouse Mus musculus

Frequency of cytogenetic disturbances was estimated in mitotically dividing bone marrow cells of CBA strain female mice after the 24-h long action of pheromone 2,5-dimethylpyrazine (2,5-DMP). The stage of the estrous cycle of each animal was taken into account at the moment of the end of the pheromone action. The analysis was performed using the anatelophase method that allows evaluating frequencies of various types of disturbances--bridges, fragments, delayed chromosomes. The spontaneous level of the mitotic disturbances revealed by the anatelophase method in animals of the control group amounts to 5.4 %. Action of pheromone 2,5-dimethylpyrasine induced the mitosis disturbances detected in the dividing bone marrow cells at the anaphase-telophase stage in the females at the di- + postestrus stage. The corresponding frequency of disturbances after the pheromone action was equal to 9.2%. In the female in estrus, the mitotic disturbance level amounted 6.7%, which did not differ statistically significantly from control. It is suggested that differences in the female mouse hormonal state at different estrous cycle stages affect sensitivity to olfactory signals. Mechanisms of the revealed effect and significance of the differences in sensitivity to pheromone for reproductive processes are discussed.     

Influence of TRPV3 mutation on hair growth cycle in mice

We recently reported that Gly573Ser substitution of the transient receptor potential cation channel, subfamily V member 3 (TRPV3) caused hair loss in DS-Nh mice. To further elucidate the effects of this mutation on the development of the spontaneous hairless phenotype, we examined the temperature-response to epidermal sheets from DS-Nh and DS mice. It was indicated that the mutation was gain-of-function. We also performed genetic and histological analyses with both strain skins. DNA microarray data revealed that the levels of keratin-associated protein 16-1, 16-3, and 16-9 genes related to the anagen phase were decreased in the skins of DS-Nh mice compared with those of three days old DS mice. Histological analysis revealed that the anagen phase persisted in DS-Nh mice, and that the telogen phase was seen in DS but not DS-Nh mice at 21 days of age. Regulation of TRPV3 appears to be important for appropriate hair development in rodents.     

A model of olfactory adaptation and sensitivity enhancement in the olfactory bulb

It has been suggested that the olfactory bulb, the first processing center after the sensory cells in the olfactory pathway, plays a role in olfactory adaptation, odor sensitivity enhancement by motivation and other olfactory psychophysical phenomena. In a mathematical model based on the bulbar anatomy and physiology, the inputs from the higher olfactory centers to the inhibitory cells in the bulb are shown to be able to modulate the response, and thus the sensitivity of the bulb to specific odor inputs. It follows that the bulb can decrease its sensitivity to a pre-existing and detected odor (adaptation) while remaining sensitive to new odors, or increase its sensitivity to interested searching odors. Other olfactory psychophysical phenomena such as cross-adaptation etc. are discussed as well.     

Influence of stage of the reproductive cycle and estradiol on thymus cell antigen presentation

The objective of this study was to determine whether thymus cells present antigen and if endocrine balance influences antigen presentation. We report here that antigen presenting cells (APC) from the thymus glands of male and female rats, when incubated with ovalbumin (OVA)-specific T cells and OVA, are functionally able to present antigen via MHC class II. To determine whether antigen presentation in the thymus is under hormonal control, tissues from female rats at different stages of the estrous cycle were analyzed. Antigen presentation was higher at estrus and proestrus than that seen at diestrus when estradiol levels are low. Estradiol given to ovariectomized animals for 3 days stimulated antigen presentation by adherent thymus cells compared to saline controls. Flow cytometry studies indicated that the adherent thymus cell preparations consisted of DC, T cells, B cells and cells of the myeloid lineage all of which expressed MHC class II, as did a small population of non-leukocytes. Antibody neutralization studies indicated that thymus cell antigen presentation involves the expression of transmembrane proteins B7.1 and B7.2. These studies demonstrate that sex hormones play a central role in regulating antigen presentation in the thymus.     

Influence of stage of oestrous cycle on time of oestrus following cloprostenol treatment in the bovine

The first of 2 injections of 0.5 mg cloprostenol (PG1 and PG2) eleven days apart was given to 19 Friesian-Hereford cross heifers between days 8-14 of their cycle (Treatment A) and 16 similar animals between days 0-4 (Treatment B). Oestrus show was monitored by Kamar Heat Mount detectors and vasectomised bulls with chin-ball markers. Blood samples taken at PG1, six days later, at PG2 and four days later were assayed for progesterone to confirm that luteolysis had occurred as expected. Four hourly rectal examinations of the ovaries were carried out from 56-112 hours after PG2 and four hourly blood samples from 36-96 hours after PG2 were collected for FSH and LH assay. Mean time in hours from PG2 to oestrus onset, LH peak and ovulation respectively was 57.4 +/- 2.9, 60.2 +/- 2.0, 91.7 +/- 1.8 for Treatment A and 64.9 +/- 4.1, 68.9 +/- 2.4, 96.7 +/- 1.3 for Treatment B. Treatment A animals showed significantly higher (p<0.01) FSH levels at PG2 than Treatment B. Time from PG2 to LH peak was significantly shorter in animals treated either on days 7 and 8 (p<0.01) or days 15-16 (p<0.05) of their cycle compared with treatment on days 12-14 and it is suggested that these shorter response times correspond to an early and late cycle wave of follicular growth. Secondary FSH peaks some 28 hours after that occurring synchronously with the pre-ovulatory LH peak were observed to be significantly (p<0.01) higher at oestrus associated with the early cycle follicular growth wave as compared with that later in the cycle which may argue a difference in endocrine control of the two periods of follicular maturation.     

Gestational stage sensitivity to ultrasound effect on postnatal growth and development of mice

BACKGROUND: An experiment was conducted to find out whether ultrasound exposure leads to changes in postnatal growth and development in the mouse. METHODS: A total of 15 pregnant Swiss albino mice were exposed to diagnostic levels of ultrasound (3.5 MHz, 65 mW/cm2, I(SPTP) = 1 mW/cm2 Intensity(Spatial Peak-Temporal Peak), I(SATA) = 240 mW/cm2 Intensity(Spatial Average-Temporal Average)) for 30 min for a single day between days 10 and 18 of gestation (GD 10-18). Virgin female mice were placed with same age group males for mating in the ratio 2 females : 1 male and examined the next morning for the presence of vaginal plug, a sign of successful copulation. The females with vaginal plugs were separated and labeled as 0-day pregnant. Maternal vaginal temperature was also measured. A sham exposed control group of 15 pregnant mice was maintained for comparison. All exposed as well as control animals were left to complete gestation and parturition. Their offspring were used in our further studies. They were monitored during early postnatal life for standard developmental markers, postnatal mortality, body weight, body length, head length, and head width, and growth restriction was recorded up to 6 weeks of age. RESULTS: An exposure to ultrasound induced nonsignificant deviations in the maternal vaginal temperature or developmental markers. Significant low birth weight was observed in the present study, after exposure at GD 11, 12, 14, and 16. However, 14 and 16 days postcoitus during the fetal period appears to be the most sensitive to the ultrasound effect, in view of the number of different effects as well as severity of most of the observed effects when exposed on these gestation days. CONCLUSIONS: The results indicate that diagnostic ultrasound can induce harmful effects on mouse growth and development when given at certain critical periods of gestation.     

Influence of cell cycle stage at nuclear transplantation on the development in vitro of mouse embryos

Nuclei were transplanted from embryos of mice at different stages of the 1st and 2nd cell cycle to oocytes enucleated at various times after fertilization. After transfer of pronuclei, a greater proportion of embryos developed to blastocysts if donor and recipient embryos were at the same stage of the cell cycle (synchronous transfer = 94%, asynchronous transfer = 76%). By contrast, when 2-cell blastomere nuclei were fused to the cytoplasm of enucleated zygotes, there was a significant effect of both cytoplast and karyoplast cell cycle stage on the development of the reconstituted embryos. Karyoplasts and cytoplasts derived from embryos at later stages of the cell cycle had greater potential to support development to blastocysts in vitro. It is suggested that the secretion of stage-specific messengers and the timing of nuclear membrane breakdown are the main factors causing the karyoplast and cytoplast effects, respectively.