Tamoxifen decreases level of immunoglobulins in blood of the hen (Gallus domesticus) without alteration in non-immunoglobular fractions of plasma proteins.

The effect of tamoxifen (TMX), an anti-estrogen compound, on immunoglobulins (Ig) level in blood plasma of laying hens was investigated. TMX (4 mg/hen/day) was given per os for seven consecutive days; control hens received placebo. Blood samples were collected from the wing vein every day before TMX treatment, and plasma Ig levels were measured by means of Rlebodzinski's test. TMX significantly decreased plasma Ig levels, maximally by 51% on day 2 of the experiment. The observed reduction in Ig level was accompanied by the significant, 37% decrease in the ratio of Ig/total protein (Tp). From the third day of TMX treatment, level of Ig and the ratio of Ig/Tp gradually increased and on the day 5 of the experiment no difference between control and experimental group was found. In non-immunoglobular (Tp-Ig) fractions of plasma proteins no significant alterations after TMX treatment were observed. Therefore, treatment of laying hens with TMX transiently decreased plasma Ig levels. Most likely the effect of TMX is associated with the antagonistic properties of TMX toward estrogen receptors. On the contrary, the transient decrease in plasma Ig levels of TMX-treated hens followed by the gradual increase suggests adaptation of the immunological system to treatment with the anti-estrogen preparation.

Effect of non-steroidal aromatase inhibitor on blood plasma ovarian steroid and thyroid hormones in laying hen (Gallus domesticus).

HyLine Brown laying hens at 30 weeks of age were treated twice daily with Fadrozole, a non-steroidal aromatase inhibitor (AI; 1 mg/kg body weight; i.m.) for six consecutive days; control hens received saline. Blood was collected every day 0.5 h after oviposition, i.e. just before AI treatment. Ovarian steroids: progesterone (P4), testosterone (T) and estradiol (E2), and iodothyronines: thyroxine (T4), triiodothyronine (T3) and reverse-triiodothyronine (rT3) were measured in blood plasma by radioimmunoassay methods. In AI-treated hens a gradual delay in oviposition time was observed. AI significantly decreased P4 and E2 levels, maximally by 43% on day 4 and by 74% on day 5, respectively, and elevated T level, maximally by 248% on day 4. Simultaneously, the increases in T4 and T3 levels with no changes in rT3 levels were observed. The maximal effect of AI on T4 and T3 levels was found on day 4 (60% increase) and day 5 (312% increase), respectively. Moreover, statistically significant, negative coefficient of correlation between E2 and T3 (r = -0.51), and positive coefficient of correlation between T and T3 (r = 0.42) in AI-treated hens were found. The results obtained indicate that in mature laying hens there is a strong relationship between ovarian steroids and thyroid hormones, and suppression of E2 synthesis not only disrupts ovarian function but also affects the activity of the thyroid gland and peripheral metabolism of thyroid hormones.

Attenuation by leptin of the effects of fasting on ovarian function in hens (Gallus domesticus).

Thirty-four-week-old laying hens received injections of recombinant chicken leptin to assess the role of leptin in avian ovarian function. In the first experiment, the hens (n=60) were divided into three groups: (i). fed ad libitum; (ii). fasted; and (iii). fasted + leptin. Hens were fasted for 5 days and those treated with leptin received 250 microg leptin kg-1 body weight twice a day, i.p. In the second experiment, the hens (n=72) were divided into four groups: (i). fed ad libitum; (ii). fasted; (iii). fasted + leptin given only during fasting (5 days); or (iv). fasted and leptin given during both fasting and 5 days of re-feeding (10 days). LH was measured in blood plasma, and progesterone and oestradiol were measured in blood plasma and the ovary by radioimmunoassay. Apoptosis was examined in the walls of the three largest yellow hierarchical follicles (F3-F1; F38-12 mm), and the granulosa layer of F3 follicles. The expression of leptin receptor in the granulosa layer of F2 and F1 follicles was barely detectable. This was in contrast to a much higher expression of leptin receptor maintained in the theca layer of F3-F1 follicles. The present results indicate that in chickens leptin might be involved in the adaptation to starvation due to attenuation of follicular apoptosis. The presence of leptin receptors in the ovary indicates the possibility of a peripheral effect of the hormone.

Presence of histamine and mast cells in chicken oviduct.

The purpose of the present study was: (1) to demonstrate immunocytochemically the localization of histamine in the wall of four chicken oviductal parts, i.e. infundibulum, magnum, isthmus, and shell gland, (2) to identify the presence of mast cells in chicken oviduct, and (3) to determine histamine concentration in oviductal tissue by the spectrofluorometric method. Experiments were carried out on Isa Brown laying hens decapitated just after oviposition. The specific immuno-reactivity for histamine and the presence of mast cells were found in the wall of all the examined oviductal parts. The immuno-reactive histamine was localized in epithelium, tubular glands, connective tissue layer, circular and longitudinal muscles, and endothelium and muscles of blood vessels. The intensity of immuno-positive reaction was as follows: infundibulum > shell gland > magnum = isthmus and correlated with quantitatively determined histamine level and tissue density of mast cells. It is suggested that mast cells are the main source of histamine in the chicken oviduct.

Simultaneous determination of plasma ovarian and thyroid hormones during sexual maturation of the hen (Gallus domesticus).

The concentrations of ovarian steroids (estradiol--E2, progesterone--P4 and testosterone--T) and thyroid hormones (thyroxine--T4 and triiodothyronine--T3) were determined in blood plasma of the domestic hen during sexual maturation and the initial period of egg lay. Blood samples were collected from Hy-Line pullets at 3 day intervals from days 87 to 144 day of life, i.e. 42 days before and 14 days after the onset of egg lay (OEL). Ovarian and thyroid hormones were measured by RIA methods. During sexual maturation an increase in ovarian steroids in the blood plasma was observed. The maximum E2 and P4 levels were recorded on day 6 and day 3 prior to OEL, respectively. In the case of plasma T level, an increase from 42 to 18 days before OEL followed by a decrease and a renewed increase from day 9 till OEL was observed. The relatively unchanged plasma level of T4 until day 9 before OEL decreased significantly just before the first oviposition while the T3 level gradually decreased between day 42 and day 9 before OEL, and then increased and again decreased from day 3 before till day 3 after OEL. During sexual maturation the following statistically significant coefficients of correlation between ovarian steroids and T3 were found: E2 vs. T3-->r = -0.551 and P4 vs. T3-->r = -0.373. There was no significant correlation between T and T3 or between the examined steroids and T4. The data obtained indicate that during sexual maturation of the domestic hen there is a negative relationship between the ovary and the thyroid gland.

Distribution of histamine in laying hen ovary.

In a laying hen, histamine was found to be present in all compartments of the ovary, i.e. stroma with follicles < 1 mm, small white (1-4 mm), large white (4-8 mm), atretic white, yellow preovulatory (8-35 mm) and postovulatory follicles. Stroma containing non-yolky follicles exhibited the highest histamine concentration (6080 +/- 331 ng/g wet wt. tissue) which differed significantly (P < 0.01) from histamine levels observed in all examined classes of ovarian follicles. High histamine concentration was found in small, large and atretic white follicles as well as in older postovulatory follicles whereas low levels of histamine contained yellow preovulatory and younger postovulatory follicles. Population of yolky white follicles presented significant (P < 0.01) differences in histamine level among small (4280 +/- 333), atretic (2940 +/- 193) and large (2010 +/- 110 ng/g) follicles. Within hierarchy of yellow preovulatory (F7-F1) follicles initial decrease in histamine concentration, from 859.3 +/- 51.5 ng/g in F7 follicle to 363.9 +/- 28.3 ng/g in F4 follicle, was followed by the increase as follicle matured, reaching the highest level in F1 follicle (711.4 +/- 35.9 ng/g). In postovulatory (P1-P5) follicles histamine concentration gradually increased as they were getting older, from 604.3 +/- 49.3 ng/g in P1 follicle to 2253 +/- 197 ng/g in P5 follicle. Determination of histamine in relation to ovulation revealed significant (P < 0.01) difference both in histamine concentration and content between the largest preovulatory F1 follicle and the largest postovulatory P1 follicle, being 0.5 h before and 0.5 h after ovulation, respectively. It is suggested that in chicken, ovarian histamine may play a role in the follicular development and/or the ovulatory process.

Changes of histamine concentration in chicken oviduct during the egg-laying cycle.

This study was undertaken to determine histamine concentration in chicken oviductal parts (infundibulum, magnum, isthmus and shell gland) in relation to the egg location within the oviduct and ovulation. The experiment was performed on Hisex Brown laying hens with regular sequences of at least four eggs. Ovulation occurred within 5-15 min of oviposition of the previous egg in the series. Histamine was determined spectrofluorometrically in the following stages of the egg-laying cycle: during c2 oviposition; 0.5 h, 6.5 h, 12.5 h and 18.5 h after c2 oviposition; and during c3 oviposition. Irrespective of the egg formation stage histamine concentration in the examined oviductal parts was arranged in the following order: infundibulum > magnum > isthmus > shell gland. During the egg-laying cycle histamine concentration significantly changed. During oviposition, i.e. just before ovulation of the next egg in the series, histamine concentration significantly increased in the infundibulum while 6.5 h after oviposition, i.e. about 1.5 h of the egg stay in the shell gland, there was a significant increase in histamine concentration both in the infundibulum and the shell gland. In the magnum histamine concentration was elevated when the ovum entered the segment, i.e. 0.5 h after oviposition. There were no changes in histamine concentration in the isthmus. It is suggested that histamine participates in the local events taking place in the hen oviduct during the egg formation cycle.

The feedback regulation of pituitary GTH-II secretion in male African catfish (Clarias gariepinus): Participation of 11-ketotestosterone.

11-ketotestosterone (OT) is a typical androgen of male teleost fish, but information on the question if it is involved in the feedback regulation of pituitary gonadotropin II (GTH-II) secretion is controversial. We have therefore studied the effects of OT on gonadotropin releasing-hormone (GnRH) stimulated GTH-II secretion in male African catfish Clarias gariepinus). In vivo experiments were carried out with intact and castrated fish. OT plasma levels were increased by implantation of silastic capsules containing 11-ketoandrostenedione (OA) which is converted to OT in both intact and castrated fish. When intact males received OA- or blank-capsules, treatment with salmon gonadotropin releasing-hormone analogue (Des-Gly(10)-D-Arg(6)-sGnRH-NEt; 0.2 µg sGnRHa/kg body weight) elevated the plasma GTH-11 levels in both groups. However, the levels were about 2 times higher in blank- than in OA-implanted fish. When castrated fish received either blank-or OA-capsules, sGnRHa treatment led to plasma GTH levels significantly higher than in sham-operated fish. However, there was no difference between the blank- or OA-implanted castrates, though OA implantation led to a restoration of OT plasma levels. This suggests that replacement ofOT is insufficient to reverse castration-induced effects. In vitro experiments were carried out with pituitary tissue fragments using a static culture system. The tissue remained sensitive to sGnRHa (5 × 10(-9)M) for 4 days after the beginning of incubation. Preincubation of pituitary tissue for 24 hours with 25 ng OT/ml medium (80 nM) completely abolished the stimulatory effect of sGnRHa on GTH-II secretion. Tritiated OT was not metabolized by pituitary tissue during 6 hours of incubation. We conclude that 11-ketotestosterone, a quantitatively prominent and non-aromatizeable circulating androgen participates, at least in part by direct action on the pituitary, in the negative feedback regulation of GnRH-stimulated GTH-II secretion in male African catfish.

Serotonin levels in the hen ovarian follicles after methallibure (I.C.I 33, 828) treatment.

The purpose of the present study was to examine the effect of methallibure (MLB), a non-steroid inhibitor of pituitary gonadotrophic activity on serotonin (5-HT) levels in the wall of preovulatory follicles (F1-F4) in the domestic hen. 5-HT was determined spectrofluorometrically. Hens were treated with MLB (10 mg/hen per os) twice a day for 3 successive days. 5-HT was determined in F1-F4 (F1 greater than F2 greater than F3 greater than F4) follicles of the control group, on the next day (MLB-1 group) and 6 days following cessation of MLB administration (MLB-6 group). During MLB treatment egg production was inhibited in all hens. In the MLB-6 group, five hens out of seven took up egg laying on the sixth day after MLB administration. Within each examined group there were no significant differences in 5-HT concentration between F1-F4 follicles. In comparison to the control, MLB caused a significant (P less than 0.01-0.05) increase of 5-HT concentration in F1 (MLB-1 group) and F4 (both MLB-groups). The results obtained indicate that there is a relationship between pituitary activity and 5-HT levels in the preovulatory follicles of the domestic hen.

Histochemical demonstration of the presence of serotonin in the hen (Gallus domesticus) reproductive tract.

The purpose of the present study was to demonstrate visually and localize the presence of serotonin (5-HT) in the ovary and oviduct of the domestic hen using a histochemical Falck-Hillarp method. Experiments were carried out on White Leghorn laying hens with no egg in the shell gland. The specific yellow fluorescence, indicating the presence of 5-HT, was found both in the ovary and all examined oviductal parts. The strongest fluorescence was present in the ovarian stroma containing small follicles with a diameter under 4 mm. In the wall of the largest preovulatory follicle a very strong fluorescence was located mainly in the theca layer. In the oviductal parts, the intensity of 5-HT fluorescence in the infundibulum and magnum was fairly strong, whereas in the isthmus and shell gland it was weak. Fluorescence seen in the infundibulum, magnum, and isthmus was primarily localized along the luminal borders of the fold surface epithelium. In the shell gland 5-HT fluorescence was found within the uterine folds, especially in the tubular glands. Moreover, the presence of an egg in the definite oviductal segment (infundibulum or isthmus) increased the intensity of yellow fluorescence in this part.

Effect of indomethacin and vasotocin on oviposition in the hen (Gallus domesticus).

The interrelationship between prostaglandins (PG) and vasotocin (AVT) in the oviposition of the domestic hen was investigated. Single or combined injections of indomethacin (IND), an inhibitor of PG synthesis, and AVT gave delay or induction of oviposition. Injection (i.m.) of IND (5 mg/kg) 5 h before oviposition resulted in 15.1 h (+/- 0.93) delay of oviposition. Injection (i.v.) of AVT (0.1 microgram/kg) 2.5 h before oviposition caused premature oviposition within a few minutes (3.1 +/- 0.2). Combined injection of IND and AVT at 5 h and 2.5 h, respectively, before oviposition caused the delay of oviposition (15.8 h +/- 0.8). The results indicate that IND blocked the induction of oviposition by AVT.