New facts and the concept of physiological regulation of the dopaminergic system function and its disorders.

We present the main results of the study and justification of our opinion on the role of dopamine (DA) retrograde transfer in the cavernous sinus in the regulation of the dopaminergic (DArgic) system activity. We are convinced that under physiological conditions DA - which is continuously retrograde transferred in the cavernous sinus from venous brain effluent to arterial blood supplying the brain and carried by the arterial blood to endothelial cells and perivascular astrocytes of striatal DArgic cell groups - can inhibit dopamine transporter (DAT) expression by a down-regulation mechanism. A new concept of the genesis of DArgic system dysfunction with involvement of DA retrograde transfer in the cavernous sinus is presented. We suggest that future research that aims to explain the genesis of hypo- or hyperfunction of the DArgic system, and DArgic system dysfunction causing Parkinson's disease, attention deficit hyperactivity disorder (ADHD), schizophrenia, and many other psychiatric disorders, must involve two areas: 1) the cavernous sinus, where DA is taken up, and transferred from the venous blood of the cavernous sinus to the arterial blood supplying the brain. To regulate this process pharmacologically, understanding the mechanism and explanation of what determines its course is necessary; 2) brain DArgic structures, whose activity is regulated primarily by the action of DAT. It is essential to clarify whether the expression of the DAT is regulated directly by DA reaching the presynaptic membrane or by any factor secreted by specific perivascular glial cells (astrocytes) under the influence of DA and DA metabolites.

Countercurrent transfer of dopamine from venous blood in the cavernous sinus to the arterial blood supplying the brain - the perfused rabbit head as an experimental model.

The objective of the current study was to check whether countercurrent transfer of dopamine occurs in the cavernous sinus of the rabbit and whether the rabbit can be used as an animal model to study cavernous sinus function. After exsanguination of the animal, oxygenated and warmed (37°C) Hanseneleit-Krebs buffer with autologous or homologous blood (in a 3:1 or 1:1 ratio) was pumped through both common carotid arteries into the head (60 ml/min; 80-100 mm Hg) and radiolabeled dopamine (3(H)-DA, 10 µCi) was infused into the cavernous sinus through the angular oculi vein. Cerebral blood from the basilar artery was collected from the cannulated vertebral artery during 3(H)-DA infusion and for 10 minutes after completion of infusion. Selected brain tissue samples were collected after completion of the head perfusion. It was demonstrated that dopamine can penetrate from the rabbit's cavernous sinus to the internal carotid artery supplying the brain. Dopamine permeation was greater when the rabbit head was perfused with buffer and blood in a 3:1 ratio than with 1:1 (P<0.01). When the head was perfused with buffer and blood in a 3:1 ratio, significant radioactivity was found in samples collected from the brain basilar artery during and after 3(H)-DA infusion (P<0.001). The radioactivity was identified as 34.13 ± 2.7% unmetabolized 3(H)-DA and 65.9 ± 2.7% its metabolites. Significant radioactivity was also found in some brain tissue samples in both groups (P<0.05). The concentration of free radiolabeled dopamine particles in the dialysate of blood plasma and plasma diluted with buffer did not differ significantly. Because the structures of the cavernous sinus and cavernous fragment of the internal carotid artery of the rabbit are similar to those in humans, it suggests that rabbits can serve as a model for experimental physiological studies of cavernous sinus function and retrograde dopamine transfer in the cavernous sinus should be considered as an important link in the genesis of Attention Deficit Hyperactivity Disorder (ADHD) and Parkinson's disease.

Local retrograde and destination transfer of physiological regulators as an important regulatory system and its role. Facts and hypothesis.

In recent decades, among many physiological regulatory systems operating as local and central controls, the mechanism of the local regulatory system based on the uptake and retrograde transfer of hormones and other physiological regulators to the places of their secretion or their destination transfer to nearby structures has become precisely understood. The system of the retrograde transfer and local destination transfer of the physiological regulators, situated between endocrine and paracrine regulation, operates primarily on the basis of specific morphological adaptations of the local blood circulatory system and lymphatic system. These adaptations enable the transfer of the regulatory molecules through the walls of blood and lymph vessels and locally increase their concentrations in the arterial blood supplying the organ secreting them (retrograde transfer) or a nearby organ (destination transfer). Extensive studies on the structure and functions of the retrograde and destination transfer system have focused on several key areas: the female and male reproductive organs, the perihypophyseal vascular complex (the venous cavernous sinus and the internal carotid artery or the rete mirabile of the internal carotid artery or maxillary artery), and the periophthalmic vascular complex (the venous ophthalmic sinus or plexus and the rete mirabile of the external ophthalmic artery). The local retrograde transfer of regulatory molecules not only allows them to be reused but also influences their production by a feedback mechanism. The local destination transfer of physiological regulators can selectively supply nearby organs with certain regulatory factors and thereby affect their function. Many observations indicate that the retrograde and local destination transfer of hormones and other biologically active substances may be a universal physiological regulatory mechanism, operating with only minor modifications in various species of animals and in humans. This review evaluates the most important published experimental studies and presents facts and hypothesis on the regulatory role of the retrograde and destination transfer of many steroid hormones, prostaglandins, pheromones, neurotransmitters (neurohormones) and CO in male and female reproductive physiology, in the physiology of the central nervous system and hypophysis and in eye function.

The role of the endometrium in endocrine regulation of the animal oestrous cycle.

A critical analysis of the results of research in the function of the endometrium was carried out and a view point presented. The role of the endometrium in endocrine regulation of the oestrus cycle can be summarized as follows: 1. The transfer of prostaglandin F(2alpha) (PGF(2alpha)) from the uterus to an ovary, which causes luteolysis, occurs mainly via the lymphatic pathways. 2. The system of retrograde transfer of PGs enables PGF(2alpha) and PGE(2) to reach the myometrium and endometrium with arterial blood at high concentration. In the luteal phase, PGF(2alpha), together with the increasing concentration of progesterone, constricts the arterial vessels of the uterus; in the follicular phase and in early pregnancy, PGE(2) together with oestrogen and embryonic signals, relaxes the arterial vessels. In addition, this system protects the corpus luteum from premature luteolysis during the cycle and luteolysis during early pregnancy. 3. In days 10-12 of the cycle, the blood flow in the uterus decreases by 60-70% in pigs and around 90% in sheep. This causes ischaemia and local hypoxia confirmed by the presence of hypoxia inducible factor and thus remodelling of the endometrium commences. 4. The pulsatile elevations in PGF(2alpha) concentration occurring in the blood flowing out of the uterus during the period of luteolysis and the next few days, do not result from increased PGF(2alpha) synthesis as suggested in numerous studies. They are the effect of excretion of PGF(2alpha) and its metabolites together with lymph and venous blood and tissue fluids in which prostaglandin accumulates.

A local pathway for increased testosterone supply from the testis to the epididymis, vas deferens and accessory genital glands of the rat.

Radiolabeled testosterone (3H-T) was infused into the testes or left and right mesofuniculus (106 dpm) or injected into a testes (2 x 10(6) dpm). The 3H-T concentration was estimated 15 or 10 min after 3H-T infusion or injection, respectively, in the tissue samples collected from the prostate, seminal vesicles, caput and cauda epididymides, vasa deferentia and the mesofuniculi. The abdominal aorta and posterior vena cava were cannulated, and the posterior part of the body perfused with blood (at blood pressure 70-140 or 260-300 mm Hg in abdominal aorta) was used to study 3H-T transfer from the testes to venous blood and other male genital organs. The concentration of 3H-T found in the accessory genital glands, epididymes and vasa deferentia was affected by blood pressure in the abdominal aorta. The reduced blood pressure and partial blocking of blood supply to the genital organs (after ligation of both testicular arteries or the terminal part of the abdominal aorta) increased the concentration of 3H-T in accessory genital glands, vasa deferentia and epididymes. The removal of the mesofuniculi and vasa deferentia with their mesoducti reduced 3H-T concentration in the prostate, seminal vesicles and cauda epididymides. Both arterial trunks, testicular arteries and common iliac arteries, were shown to be connected by anastomoses in target organs so effectively, that supplying the male genital organs with blood by only one of them assures the transfer of testosterone from the testes to the epididymes, vasa deferentia, mesofuniculi as well as prostate and seminal vesicles. It was concluded that lymphatic vessels of the mesofunicules and of the spermatic cords as well as venous and arterial vasculature of the mesofunicules create a recently unknown pathway for the increase of testosterone supply from the testes to the epididymes, vasa deferentia and accessory genital glands of rats.

Retrograde transfer of ovarian steroid hormones to the ovary in the porcine periovarian vascular complex.

The aim of the present study was to investigate the mechanism of the retrograde transfer of ovarian steroid hormones from the ovarian lymphatic and venous effluent to the arterial blood supplying the ovary. In the first experiment, reproductive organs were collected from gilts in the luteal (n = 10) and follicular (n = 10) phase of the oestrous cycle. The ovary with the mesovarium was isolated and perfused through the ovarian artery with warmed, oxygenated autologous blood. The concentrations of progesterone and oestradiol in ovarian arterial blood increased on passing through the ovarian artery to the ovary, in the luteal phase, from 20.3 +/- 2.1 to 31.4 +/- 3.9 ng ml(-1) (P < 0.001) and from 6.2 +/- 0.8 to 11.4 +/- 1.4 pg ml(-1) (P < 0.001), respectively, and in the follicular phase, from 1.2 +/- 0.2 to 2.2 +/- 0.4 ng ml(-1) (P < 0.001) and from 8.2 +/- 1.8 to 13.2 +/- 2.3 pg ml(-1) (P < 0.001), respectively. Approximately 17.5 +/- 3.9 % of the progesterone and 12.6 +/- 1.7 % of the oestradiol found in the ovarian venous effluent was retrogradely transferred from the ovarian venous blood to the ovary in the luteal phase. In the follicular phase, these values were 10.1 +/- 2.0 % and 8.6 +/- 1.4 %, respectively. The efficiency of retrograde transfer of oestradiol and the rate of retrograde transfer of progesterone differed between phases of the oestrous cycle (P < 0.05 and P < 0.0001, respectively). A direct relationship between the concentration of the steroids in the venous effluent and the efficiency and rate of the retrograde transfer to the ovary was not found. In the second experiment (luteal phase, n = 10; follicular phase, n = 5), the concentration of progesterone and oestradiol increased in both ovarian arterial blood (P < 0.0001) and in the venous effluent (P < 0.0001) after administration of the steroids into the lymphatic vessels of the isolated mesovarium with separated ovary. In the third experiment (follicular phase, n = 5), with the mesovarium isolated after the ovary was removed and ovarian venous blood flowing out under the force of gravity (without the blood pressure in the ovarian vein), it was demonstrated that the veno-venous network covering the branches of the ovarian artery was supplied with the blood flowing out from the mesovarian tissue and that the filling of the veno-venous network was dependent on the blood pressure in the ovarian artery. We conclude that the effective retrograde transfer of steroid hormones from ovarian venous and lymphatic effluent to the ovary is accomplished not only by the classical counter-current exchange mechanism, but also as a result of complex processes that may be dependent on a specific part of the circulation of the blood and lymph in the periovarian vascular complex of the mesovarium.

Humoral pathway for local transfer of the priming pheromone androstenol from the nasal cavity to the brain and hypophysis in anaesthetized gilts.

It is generally accepted that pheromones act by stimulating of the dendritic receptors of the olfactory neurones massed in the olfactory epithelium. This study was designed to ascertain whether it is possible for the boar pheromone androstenol (5alpha-androst-16-en-3-ol) to be transported from the nasal cavity of anaesthetized gilts to the brain and hypophysis via local transfer from the blood in the perihypophyseal vascular complex. The experiment was performed on days 18-21 of the porcine oestrous cycle (crossbred gilts, n = 6). Tritiated androstenol (3H-A; total amount 10(8) d.p.m. (758 ng)) was applied for 1 min onto the respiratory part of the nasal mucosa, 4-6 cm from the opening of the nares. Arterial blood samples from the aorta and from the carotid rete were collected every 2 min during the 60 min period following administration of the steroid. Total radioactive venous effluent from the head was removed and an adequate volume of homologous blood was transfused into the heart through the carotid external vein. At the end of the experiment gilts were killed and tissue samples of the hypophysis and some brain structures were collected to measure radioactivity. In addition, corresponding control tissues were collected from three untreated gilts and from three heads of gilts 60 min after 3H-A was applied post mortem into the nasal cavity. The concentration of 3H-A was significantly higher (P < 0.0001) in the arterial blood of the carotid rete than that of aorta. The mean rate of 3H-A counter current transfer from venous to arterial blood in the perihypophyseal vascular complex, expressed as the ratio of the 3H-A concentration in arterial blood of the carotid rete to the 3H-A concentration in blood sampled simultaneously from the aorta, was 1.96 +/- 0.1. The concentration of 3H-A in plasma from the venous effluent from the head ranged from 1.3 to 1.8 pg x ml(-1). During the 60 min period of the experiment, 0.68% of the total applied dose of 3H-A was resorbed from the nasal cavity into the venous blood. Moreover, we found that 3H-A was present in the olfactory bulb (P <0.01), amygdala, septum, hypothalamus, adenohypophysis, neurohypophysis (P > 0.05) and perihypophyseal vascular complex (P < 0.01). These results demonstrate that, in anaesthetized gilts, the boar pheromone androstenol may be resorbed from the nasal mucosa, transferred in the perihypophyseal vascular complex into arterial blood supplying the brain and hypophysis, and then arrested in the hypophysis and certain brain structures. We suggest that in addition to the standard neural pathway for signalling pheromones, another pathway exists whereby androstenol, as a priming pheromone, may be resorbed from the nasal cavity into the bloodstream and then pass locally from the perihypophyseal vascular complex into the arterial blood supplying the brain and hypophysis, thus avoiding the first passage metabolism in the liver.

Humoral pathway for transfer of the boar pheromone, androstenol, from the nasal mucosa to the brain and hypophysis of gilts.

Signaling and priming pheromones play an important role in intraspecies behavioral and sexual interactions and in the control of reproduction. It is generally accepted that pheromones act by stimulating the dendritic receptors in the mucus-imbedded cilia of olfactory neurons massed in the olfactory epithelium. The boar pheromone androstenol, known to induce sexual behavior in pigs, is 1 of 2 pheromones that have been chemically defined, tritiated and thus made available for use in studies. In Experiment 1, sexually mature cyclic gilts at Days 16 to 21 of the estrous cycle were humanely killed and the heads separated from the bodies. The heads were attached to a perfusion system using heated, oxygenated, heparinized, autologous blood. A total amount of 10(8) dpm (758 ng) of 3H-5 alpha-androstenol (3HA) was either infused into the angularis oculi veins that drain the nasal cavities (n = 7) over a 5-min period or applied through intranasal catheters onto the mucose surface (n = 16) for 2 min. In both groups frequent blood samples were collected from the carotid rete and from venous effluent. Concentration of 3HA in the arterial blood of the carotid rete after direct (into angularis oculi veins) or indirect (onto the nasal mucosa) administration of 3HA into veins draining the nasal cavities was significantly higher than background radioactivity before 3HA administration (P < 0.0001 and P < 0.05, respectively). The 3HA was selectively accumulated (compared with the respective control tissue) in the neurohypophysis (P < 0.001), adenohypophysis (P < 0.01), ventromedial hypothalamus (P < 0.05), corpus mammillare (P < 0.01), and perihypophyseal vascular complex (P < 0.001). In a second in vitro experiment, active uptake of 3HA into the nasal mucosa of the proximal, respiratory segment of the nasal cavity was observed. These results demonstrate a humoral pathway for the transfer of pheromones from the nasal cavity to the hypophysis and brain. Androstenol was taken up by the respiratory part of the nasal mucosa, resorbed into blood, transported to the cavernous sinus and transferred into the arterial blood of the carotid rete (supplying the hypophysis and brain), and then selectively accumulated in the hypophysis and certain brain structures.

Local increase of ovarian steroid hormone concentration in blood supplying the oviduct and uterus during early pregnancy of sows.

Countercurrent transfer in the ovarian vascular pedicle elevates the concentration of steroid hormones in blood supplying the oviduct and periovarian part of the uterus during the estrous cycle in the pig. This study was conducted to determine whether during early pregnancy the arterial blood supply to the oviduct and uterus carries greater concentration of steroid hormone than systemic blood. The concentration of ovarian steroid hormones (progesterone, estradiol-17 beta, estrone, androstenedione and testosterone) was measured in 40 gilts on Days 12, 18, 25 or 35 of pregnancy. Silastic catheters were inserted: a) into the jugular vein, b) into the branch of uterine artery close to the ovary (proximal to the ovary) and c) into the branch of the uterine artery close to the cervix (distal to the ovary). On the day following surgery simultaneous blood samples from cannulated vessels were collected every 20 min for 3 hours. The concentration of steroid hormones was determined by radioimmunoassay. The mean concentrations of studied hormones in branches of the uterine artery proximal and distal to the ovary were significantly greater than in the jugular vein (P < 0.001) by 18 to 69% and 7 to 31%, respectively. The concentrations of hormones in proximal and distal to the ovary branch of the uterine artery were also significantly different (P < 0.001). The increase in concentrations of the measured hormones did not differ considerably between investigated days of pregnancy. It is concluded that during maternal recognition of pregnancy, formation of the corpus luteum of pregnancy, implantation of the embryo and the placenta elongation the oviduct and uterus are supplied with locally elevated concentration of steroid hormones compared to systemic blood.

Countercurrent transfer of 125I-LHRH in the perihypophyseal cavernous sinus-carotid rete vascular complex, demonstrated on isolated pig heads perfused with autologous blood.

The objective of the study was to determine whether the local permeability of luteinizing hormone-releasing hormone (LHRH) from the venous blood of the perihypophyseal cavernous sinus into the arterial blood of the carotid rete, supplying the brain and hypophysis in gilts, depends on the day of the estrous cycle, as well as to determine whether this transfer exists when LH concentration in the blood is reduced (the experimental short-loop negative feedback for LH secretion after estradiol injection in ovariectomized gilts). Experiments were conducted on isolated gilt heads with necks, on chosen days of the estrous cycle (n = 40), and on previously ovariectomized gilts treated with estradiol benzoate (EB) (n = 5) or corn oil (n = 3). After exsanguination, the gilt heads with necks were disarticulated and about 30-45 min later were supplied with autologous, oxygenated, and heated blood at a stable blood flow and pressure through the left carotid artery for 30 min. 125I-LHRH was infused into both cavernous sinuses through the cannulated angularis oculi veins for 5 min. After 125I-LHRH infusion, radiolabeled LHRH was found (P < 0.001) in arterial blood taken from the carotid rete through the open right carotid artery in all animals used in the experiment: on Days 1-2 (six gilts), on Days 12-14 (seven gilts) of the estrous cycle, and in five ovariectomized gilts during negative feedback for LH surge (40 hr after EB). No significant radioactivity of 125I-LHRH was found in the arterial blood on Days 3-5 (n = 6), 9-11 (n = 4), and 15-21 (n = 17) of the estrous cycle. A very low level of radioactivity was found in the ovariectomized control group after the injection of corn oil (n = 3). These results provide evidence for the permeability of LHRH from the venous to the arterial blood and its retrograde transport with the arterial blood to the hypophysis and brain, after the ovulation period (Days 1-2) and on Days 12-14 of the estrous cycle. This suggests that a close relationship exists between the day of the estrous cycle and LHRH permeability from the venous to the arterial blood in the perihypophyseal cavernous sinus-the carotid rete complex in gilts-and that this mechanism may be included in a short-loop feedback for LHRH secretion.

Involvement of adrenoceptors in the ovarian vascular pedicle in the regulation of counter current transfer of steroid hormones to the arterial blood supplying the oviduct and uterus of pigs.

1. On Day 10 of the oestrous cycle in pigs, after laparotomy noradrenaline (NA), methoxamine (alpha 1-adrenomimetic, M), Prazosin (alpha 1-adrenolytic, Pr) in total doses of 4 mumol, and saline were infused (10 min) into the superficial layer of mesovarium on both sides of the ovarian pedicle vasculature, close to the ovary. 2. Blood flow in the ovarian artery, heart rate and progesterone (P4) and androstenedione (A4) secretion from the ovary and their concentrations in the ovarian venous effluent, as well as the concentrations of P4 and A4 in the blood supplying the oviduct and the uterus, were determined. 3. A significant increase of P4 and A4 secretion after NA and M infusion and increased concentrations of P4 and A4 in the ovarian venous effluent were found, but these changes did not influence the counter current transfer of hormones from the venous effluent into arterial blood supplying the oviduct and the uterus. 4. Infusion of Pr caused a significant decrease of P4 and A4 secretion and their concentrations in the ovarian venous effluent and significantly increased A4 concentration in the blood supplying the oviduct and uterus. 5. The results indicate that stimulation of alpha 1-adrenoceptors in the area of ovarian vasculature did not influence, whereas block of alpha 1-adrenoceptors affected, the local concentration of steroid hormones in the blood supplying the oviduct and the part of the uterus proximal to the ovary, despite the changes in the concentrations of steroid hormones in the ovarian effluent.

Counter current transfer of beta-endorphin in the perihypophyseal cavernous sinus--carotid rete vascular complex of sheep.

This study was performed to answer the question of whether counter current retrograde transfer of beta-endorphin in the perihypophyseal cavernous sinus-carotid rete vascular complex depends on the reproductive activity of sheep and if this transfer depends on membrane Na+ K+ ATP-ase blocking by ouabain. Sheep were anaesthetised and the jugular vein and the carotid artery were cannulated on both sides. Multielectrolitical liquids (Solfin, Polfa "Kutno", Poland): 500 ml of Solfin with heparin (25,000 IU), or Solfin with heparin and ouabain (Sigma, St. Louis, USA) in concentrations of 10(-5) or 10(-4) mol 1(-1) were infused into the brain through the carotid artery. Heparinized blood was collected through the carotid artery. After exsanguination, the head with the neck was removed. The isolated head was supplied with oxygenated, heated, autologous blood diluted with Solfin (4:1) without or with ouabain in concentration of 10(-5) or 10(-4) mol 1(-1). Blood pressure and temperature were measured throughout the duration of the experiment. During the experiment 125I-beta-endorphin (7.9 x 107 dpm) dissolved in 10 ml of Solfin was infused for 5 min (5 ml) into each cavernous sinus through the angularis oculi veins. Blood samples for radioactivity measurements were collected each min from the carotid rete (through the opposite carotid artery to the artery supplying the brain with arterial blood) and from both jugular veins. In all the experiments significant 125I-beta-endorphin radioactivity was found in arterial blood supplying the brain and hypophysis in the early luteal phase in sheep. No radioactivity was found (with the exception of one animal) in sheep during seasonal anoestrus. A blockage of Na+ K+ ATP-ase by ouabain administered during exsanguination and during head perfusion with dose of 10(-4) mol 1(-1) reduced beta-endorphin counter current transfer to arterial blood, but this effect was not evident with the dose of 10(-5) mol 1(-1). Increased blood pressure was observed in all the experiments with either dose of ouabain.

Counter current transfer of oxytocin from the venous blood of the perihypophyseal cavernous sinus to the arterial blood of carotid rete supplying the hypophysis and brain depends on the phase of the estrous cycle in pigs.

The objective of the present study was to determine whether or not the neuropeptide, oxytocin, can move by counter current transfer from venous blood of the perihypophyseal cavernous sinus into arterial blood of the carotid rete supplying the brain and hypophysis, and also whether this exchange depends on the day of the estrous cycle. Isolated heads of gilts (n = 37), on different days of the estrous cycle, were supplied with autologous, oxygenated and heated blood at a stable blood flow and pressure through the right carotid artery for 30 min. 125I-Oxytocin (125I-OT) was infused into both cavernous sinuses through the angularis oculi veins for 5 min. After 125I-OT infusion, radiolabeled oxytocin was found in arterial blood taken from the carotid rete in all 7 gilts on Days 1-3, and in 7 of 9 gilts on Days 12-13 of the estrous cycle. In general, the level of radioactivity in arterial blood during Days 12-13 was significantly lower (p < 0.002) than during Days 1-3 of the estrous cycle. No 125I-OT was found in arterial blood from Days 4 through 11 (n = 10) or from Day 14 to the beginning of ovulation (n = 11). These results provide evidence for the counter current transfer of oxytocin from hypophyseal and brain venous effluent (cavernous sinus) to arterial blood supplying the hypophysis and brain, during the ovulation period and the late luteal phase of the estrous cycle. The meaning of this process is not as yet known and needs further study.

Total content of prostaglandin F2 alpha in the endometrium and myometrium from various sections of the porcine uterine horn during the estrous cycle.

The purpose of this study was to determine effects of various stages of the estrous cycle on the content and concentration of PGF2 alpha in endometrium and myometrium in different segment of the uterine horn and whether different methods of expressing PGF2 alpha data would affect interpretation of results. Total content of PGF2 alpha in the endometrium and myometrium of the entire uterine horn, and PGF2 alpha concentrations in five sections of uterine horn each of equal length (1 to 5 beginning from the ovarian end) were measured in gilts during three different phases of the estrous cycle: the early luteal phase (Days 3 to 6 of the estrous cycle), mid-luteal phase (Days 9 to 12), and during luteolysis (Days 15 to 18). The total content of PGF2 alpha in the early and mid-luteal phases was similar (P > or = 0.05) in both the endometrium and myometrium. During luteolysis the content of PGF2 alpha in the endometrium and myometrium increased 7-fold and 4-fold, respectively, when compared to the early luteal phase. The distribution of PGF2 alpha was similar throughout the length of the uterine horn and this did not change during the phases of the cycle studied. The PGF2 alpha concentrations during different phases of the estrous cycle differed with methods of expressing the data i.e. ng g-1 tissue, ng mg-1 DNA, ng mg-1 protein, but the relative differences were not appreciably altered.

Rapid absorption and local redistribution of progesterone after vaginal application in gilts.

Catheters were implanted in 6 anaesthetized gilts (3 animals in the follicular phase, 3 in the luteal phase) into a carotid artery and into the utero-ovarian vein and uterine artery on both sides. The uterine lumina were closed by a suture. Further, a catheter was inserted into the vagina after which the animals were allowed to recover. Tritiated progesterone was infused into vagina the following day during a 2 min period and simultaneous blood samples collected from the 5 catheters every 10 min for 2 h after which the animals were sacrificed. Tissue samples were obtained from the genital organs. The results showed a rapid absorption of progesterone from the vaginal lumen and a marked redistribution to the genital organs. The increased level of radioactivity in the plasma samples collected from the uterine arteries compared to the simultaneous samples from the carotid artery in 2 of the 3 animals in the luteal phase indicates the existence of a local redistribution system.

New pathways in animal reproductive physiology frontiers and perspectives.

With the inrush of new data the recent clear division of neural, hormonal and immunological regulation has been seriously complicated. Both central and peripheral neural tissue produce over 30 neuropeptides, among which are many classic peptide hormones. A steroid biosynthetic pathway has been demonstrated in oligodendrocytes. However, the distribution and role of peptydoergic neurons within the reproductive system are only superficially known among farm animals. Neurons have receptors for many hormones and interleukins. Cells of the immune system, in addition to secretion of many interleukins and interferons, produce neuropeptides locally and they possess specific receptors for them as well. Till now, the interaction between the nervous, hormonal and immunological systems has not been taken into account while investigating the functions of ovarian follicles, the corpus luteum, oviduct and uterus. The penetration of blood and lymphatic vessels by hormones, neuropeptides and cytokins has not been taken into consideration also. The counter current transfer of many steroid and peptide hormones from ovarian venous and lymphatic effluent to arterial blood supplying the ovary and through arterial anastomoses of the oviduct and uterus has been hithero shown. It has been demonstrated that thanks to this system, arterial blood supplying the uterus and oviduct has, in physiological conditions, a much higher level of some steroid hormones such as progesterone and androstendione, 37% and 36% respectively, than in systemic blood. Recently, a powerful exchange system for resupplying hormones to the brain which is dependent on the phase of the estrous cycle, has been discovered. It has also been demonstrated that neuropeptides LH-RH, beta-endorphin and oxytocin as well as the steroid hormone progesterone, were counter current transferred from venous to arterial blood at the perihypophyseal cavernous sinus and carotid rete in sheep and gilts, but only during specific periods of reproductive activity. The mechanism of this process is still unknown. The role of peptydoergic neurons and cytokins in vascular permeability during hormone counter current transfer in the broad ligament vasculature, perihypophyseal cavernous sinus and carotid rete has not been investigated. It is suggested that progress in this area may change our point of view on many basic regulatory mechanisms involved in animal reproductive physiology.

Counter current transfer and back transport of 3H-PGF2 alpha in the cow's broad ligament vasculature ipsilateral and contralateral to the corpus luteum.

Eight cows of similar age (5-7 years) were chosen for the experiment. Isolated reproductive tract was supplied with autologous oxygenated and heated (40 degrees C) blood through the uterine artery and ovarian artery. 3H-PGF2 alpha in total dose of 2 MBq (10(7) cpm) was injected into each of the uterine lumen of isolated organ. Blood samples were collected at 5 min intervals during 120 min of experiment using cannulae inserted into the branches of uterine arteries about 1 cm below the horns and from ovarian arteries inserted 0.5 cm below the ovaries. The concentration of 3H-PGF2 alpha found in blood plasma taken from uterine artery or from ovarian artery on the side with active corpus luteum (CL) was significantly lower (p less than 0.001) compare with contralateral side to active CL. Radioactive PGF2 alpha found in branches of uterine arteries on both ipsilateral and contralateral side to CL was significantly higher (p less than 0.001) compare to ovarian artery of the same side. It is concluded that absorption of 3H-PGF2 alpha from uterine lumen into venous blood as well as its counter current transfer in area of broad ligament vasculature were reduced on the side of uterine horn with active CL probably as an effect of estrogen:progesterone ratio on vascular constriction in area of uterine vasculature.

Counter current transfer of PGF2 alpha in the mesometrial vessels as a mechanism for prevention of luteal regression in early pregnancy.

A new concept has been presented on the mechanism protecting the corpus luteum during oestrous cycle, early pregnancy and pseudopregnancy induced by oestrogens. The concept is based on the recently discovered mechanism of back transfer of prostaglandin F2 alpha from the broad ligament vasculature into the uterus and on the participation of oestrogen in this process. The morphological facilitates for counter-current transfer of PGF2 alpha in the area of mesometrial vasculature and ability the uterus to bind PGF2 alpha were presented. It has been concluded that the process of PGF2 alpha back-transfer from mesometrial vasculature into the uterus may reduce in uterine venous blood the amplitude of PGF2 alpha pulses and by this way may reduce the penetration of prostaglandin into subovarian area and from there to the corpus luteum.

Role of mesovarium and mesosalpinx in counter current exchange of hormones.

On the base of own studies with counter current transfer of steroid hormones and PGF2 alpha and the data taken from the literature it is suggested that two parts of broad ligament of the uterus i.e. mesovarium and mesosalpinx are not only morphological structures keeping the ovary, oviduct and ovarian vasculature, but that they may take part in hormonal regulation of the ovarian function.