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Sex difference in rabbit eyelid conditioning

100%
Orlowska-Majdak M., Kolodziejski P., Traczyk W. Z.
Acta Neurobiologiae Experimentalis
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2001
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vol. 61
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issue 2
135-140
EN
The rabbit eyelid conditioned reflex has been used to compare associative learning in males and ovariectomized females. A new method for monitoring eyelid movements is described. Rabbits were trained on simple delay classical conditioning. Conditioned responses were recorded during 8 acquisition days and 6 days of extinction training. Analysis of variance (ANOVA) and the least significant difference (LSD) post hoc test was used to analyse the data. The results showed that males achieved significantly better learning than females during the 1st day of acquisition but later they slowly attained the best result, contrary to females. Moreover, extinction of the conditioned reflex was significantly faster in females than in males. It is postulated that females learn and extinguish faster than males because of a higher level of brain plasticity.
2

Effect of 9-cis retinoic acid (RA) on sex hormone secretion and RA receptor expression in chicken ovarian follicles

88%
Pawlowska K., Sechman A., Suchanek I., Grzegorzewska A., Rzasa J.
Folia Biologica
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2008
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vol. 56
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issue 1-2
65-72
EN
Several lines of evidence indicate that retinoids, derivates of vitamin A, affect reproductive function in birds, however, the mechanism of their action in the ovary is still unknown. Therefore, the present study was designed (i) to show whether in the domestic hen 9-cis retinoic acid (9-cis RA), one of the retinoids, influences steroid secretion in vitro by white and yellow chicken ovarian follicles, and (ii) to detect expression of retinoic acid RXR receptor mRNA in these follicles. The white follicles (small: 1-4 mm, medium: 4-6 mm and large 6-8 mm in diameter) and the three largest yellow preovulatory follicles (F3-F1; 25-37 mm) were isolated from the ovary 3 h before ovulation. The granulosa layer was separated from the theca layer in the preovulatory follicles, which were subsequently divided into 4 equal pieces. The isolated whole white follicles or parts of the granulosa or theca layers were incubated for 24 h at 38oC in Eagle's medium in the following 4 groups: control, ovine LH (oLH; 10 ng/ml), 9-cis RA (100 ng/ml) and 9-cis RA + oLH. After incubation, the medium was collected for estradiol (E2) and progesterone (P4) determination while tissues were saved for protein assay. It was found that 9-cis RA affects steroid secretion from chicken ovarian follicles. It decreased E2 secretion from white follicles and from the theca layer of the two largest (F2 and F1) preovulatory follicles. 9-cis RA had no effect on oLH-stimulated E2 secretion by the white follicles and yellow F2 and F1 follicles, but it diminished E2 secretion by F3 follicles. As regards P4, the effect of 9-cis RA was opposite; it increased P4 secretion from the granulosa layer of all preovulatory follicles. 9-cis RA did not change oLH-stimulated P4 secretion by granulosa layers of F3 and F2 follicles, however, it inhibited oLH-enhanced P4 secretion from the F1 granulosa layer. In a separate experiment, the presence of mRNA encoding RXR was found in the stroma and all follicles of the chicken ovary by means of the RT-PCR technique. The results indicate that retinoids, acting by specific nuclear receptors, are modulators of follicular steroidogenesis in the chicken ovary.
3

Gonadotropins and sex hormones modulate interrenal function in soft-shelled turtle

88%
Ray P. P., Maiti B. R.
Folia Biologica
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2002
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vol. 50
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issue 3-4
115-120
EN
The aim of the current work was to investigate the role of gonadotropins and female sex hormones on interrenal activity in soft-shelled turtles, Lissemys punctata punctata. 1) FSH treatment (3 mug/100 g body wt daily for 10 days) caused interrenal hypertrophy with increased nuclear diameter, raises of acid phosphatase and alkaline phosphatase concentrations, and depletions of cholesterol (except the free fraction) and ascorbic acid levels from the interrenal gland. However, LH treatment (3 mug/100 g body wt daily for 10 days) failed to produce any perceptible change in the interrenal activity. The combined treatments of FSH and LH (3 mug each/100 gm body wt daily for 10 days) produced no further change beyond that of FSH alone. 2) Estrogen treatment with the low dose (25 mug/100 g body wt daily for 10 days) had no effect, but with higher doses (50 mug or 100 mug/100 gm body wt daily for 10 days) is caused interrenal stimulation by inducing the same manifestations to those of FSH. The degree of manifestations was higher with the higher dose (100 mug daily) than that of the moderate dose (50 mug daily). Progesterone treatment with the low dose (25 mug / 100 g body wt daily for 10 days) had no significant effect, but with the moderate (50 mug daily) and higher (100 mug daily) doses suppressed interrenal activity by showing the reverse changes to those of estrogen. The degree of manifestations was higher with the higher dose than that of the moderate one. The combined treatments of estrogen and progesterone (100 mug each/100 g body wt daily for 10 days) caused interrenal stimulation but to a lesser extent than that of estrogen alone. The findings are briefly discussed.
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