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V Zbuzek

Publications and source records attributed to V Zbuzek.

14 recordsLinked to original sources
PubMed1999

Effect of pre- and postnatal nicotine exposure on vasopressinergic system in rats.

Timed pregnant Sprague-Dawley rats were infused subcutaneously either with nicotine (NIC, 6 mg kg-1 day-1; n=17) or saline (control, n=15) on the 3rd day of gestation, via Alzet osmotic pumps, for 28 days. After the parturition, the pups of both, control and NIC infused dams, were each randomly divided into 2 groups and placed to be nursed as following: (1) control dams nursing pups born to control mother (control group); (2) control dams nursing pups born to NIC-infused mother (prenatal NIC group); (3) NIC-infused dams nursing pups born to control mother (postnatal NIC group); (4) NIC-infused dams nursing pups born to NIC-infused mother (pre- and postnatal NIC group). Vasopressin (VP) was measured by RIA in plasma, neurointermediate lobe (NIL) and hypothalamus (HT) in the pups of both sexes, at the following age: 0 (within 24 h after birth); 1, 2, 3, 4 and 6 weeks. At the age of 3, 4 and 6 weeks, the isolated NILs were individually superfused and VP was measured as a basal release and the response to a 10-min 56 mM potassium stimulation. A marked suppression in the activity of VP-ergic system was observed in both sexes of offspring exposed to NIC prenatally, being first detectable at the age of 3 weeks, when the HT-NIL system becomes fully developed. However, the significant changes were observed at the age of 6 weeks: decreased serum VP concentration, lower VP contents in the HT and NIL, and suppressed VP release, basal and stimulated, from the isolated NIL. Postnatal exposure to nicotine was ineffective.

Aging↗
PubMed1991

Age-related differences in concomitant hormone release from the superfused rat adenopituitary.

We screened the concomitant release of five adenopituitary (AP) hormones, in vitro, at basal and stimulated conditions, in young and aged (2-3 and 25 months old, respectively) male Fischer 344 rats. The APs of aged rats exhibited significantly higher basal and total release of prolactin, but lower release of luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone and growth hormone than those of young rats. The APs of aged rats did not respond to high K+ depolarization by an increased release of any of the studied hormones, whereas the APs of young rats did release a significant amount in all instances. The results indicate marked age-related alterations affecting the release of the hormones, detectable even in the isolated AP alone.

Aging↗
PubMed1988

Neurohypophyseal aging: differential changes in oxytocin and vasopressin release, studied in Fischer 344 and Sprague-Dawley rats.

We had previously shown that the hypothalamo-neurohypophyseal vasopressin secreting system is suppressed in aged rats. In the present study, using aged (26 months) male Fischer 344 (F344) rats, we showed that in contrast to vasopressin, oxytocin plasma concentration and hypothalamic content were unaltered in comparison with young (2-3 months) rats; however, based on data from our past and current studies, the neurohypophyseal concentrations of both hormones were found to be decreased in aged rats. We also compared the effect of aging on the oxytocin and vasopressin in secretory functions. Superfusion technique was employed to examine oxytocin and vasopressin release from isolated neural lobes of young (2-3 months) and old (26 months) male F344 and young (2-3 months), middle-aged (12 months) and old (30 months) Sprague-Dawley (SD) rats. Aging affected basal release of oxytocin and vasopressin in a differential manner. Expressed per gland, basal release of oxytocin increased in aged rats of both strains; whereas vasopressin release decreased in SD, and did not change in F344, old rats. The vasopressin responses to electrical stimulation, 56 mM K+ and initial traumatic release were decreased in aged rats; whereas oxytocin responses were either unaltered or decreased much less. All age-related changes were more pronounced in SD than in F344 rats. Thus, while the aging process is associated with a significant impairment in the vasopressin secretory function, the oxytocin secretory function is much less affected by that process. Significant strain differences were observed in the effects of aging on oxytocin and vasopressin release.

Aging↗
PubMed1987

Age-related differences in the incorporation of 3H-arginine into vasopressin in Fischer 344 rats.

We studied the effect of aging on the incorporation of 3H-arginine into vasopressin (VP) molecule in the hypothalamus (HT) and the rate of its transport into the neurohypophysis (NH) of male Fischer 344 rats of different ages: 2-3 months (young, n = 28), 11-13 months (adult, n = 30) and 30 months (old, n = 27). 3H-arginine was injected in a single dose through a permanent cannula into the lateral ventricle of an awake animal. The rats were decapitated 1, 6, and 24 h after the injection. VP was extracted from individual HTs and NHs (without pars intermedia), purified in a chromatography column and determined by RIA. Hypothalamus: One hour after the injection the 3H-activity was highest in the young, lower in the adult and lowest in the old rats, whereas the specific activity (cpm/pg VP) was similar in all age groups, reflecting endogenous VP content to be highest in the young, lower in the adult and lowest in the old rats. In the young rats both activities decreased 6 and 24 h after the injection. The adult rats also exhibited declining activities, whereas in the old rats the activities remained unchanged from 1 to 24 h after the injection. Neurohypophysis: One hour after the injection of radioactive label 3H-activity and specific activity were significantly lower in the NH of the old than in those of young and adult rats. The activities increased 6 h after the injection in all age groups with the lowest values in the old rats. After 6 h, both activities in the old rats reached only the 1-h values of the young and adult rats suggesting a delay of at least 6 h in the axonal transport of newly synthetized VP in aged rats. Twenty-four hours after the injection both activities increased in all age groups exhibiting no difference among the age groups, indicating a decreased release of the newly synthetized VP from the NH of aged rats. These data demonstrate an age-related decrease in the rate of incorporation of 3H-arginine into VP, in the rate of its axonal transport and in the release of newly synthetized VP from the NH of Fischer 344 rats.

Aging↗
PubMed1986

Decremental vasopressin release after repeated stimulation of superfused neurohypophyses of Fisher 344 rats of different ages.

We studied the effect of aging on the decline in vasopressin (VP) release from the rat neurohypophyses (NH) as evoked by repeated stimuli with high K+ (56 mM) Locke's solution in vitro. Isolated NHs, without pars intermedia, of 2-, 12- and 30-month-old male Fisher 344 rats arbitrarily labeled as young, adult, and old were individually superfused with synthetic medium TC 199. Following the initial traumatic release, the glands were stimulated three times for 10 min each with recovery periods of 35 min between stimulations. VP was measured by radioimmunoassay. Expressed per mg NH, basal VP release in the old rats, and stimulated VP release in both the adult and old rats, was decreased. The gradual decline (slope) of VP release following subsequent stimuli with high K+ was proportional, however, in all age groups. Thus, decreasing response of VP release to repeated stimulation is a function of the initial response but is not age related. These findings suggest that only some components of the chain of events involved in the release mechanisms are impaired in aging animals, whereas others may remain unaffected.

Age Factors↗
PubMed1984

Vasopressin release from individually superfused neurohypophyses decreases in aged rats.

We studied the effect of aging on vasopressin (VP) release from isolated neurohypophyses (NH) individually superfused with synthetic medium TC 199 with Hanks' salts. The superfusion technique is described in detail. Male Fisher 344 rats 2 months (young, n = 17), 12 months (adult, n = 14) and 30 months (old, n = 17) of age were used. VP was measured by radioimmunoassay (RIA). The age-related VP release was analyzed as follows: initial traumatic release, basal release, VP release evoked by electrical stimulation (10-second trains every 20 s of matched biphasic stimuli, 0.2 ms width, 8 mA, 30 Hz), by chemical stimulation (56 mM K+) and total release for the entire superfusion period. When VP release was expressed per milligram NH, it was significantly lower under all conditions in the old rats than in the young ones. In the adult rats, traumatic, basal and total release values were similar to those of the young rats, whereas their responses to chemical and electrical stimulation were similar to those of old rats. Residual VP content expressed per whole NH was significantly higher in the old and adult rats, reflecting a larger glandular size, but when expressed per milligram NH tissue, it was low in the old rats. The percent of VP released during the entire superfusion period relative to the residual VP content was significantly lower in the old than in the young and adult rats. The magnitude of the maximal VP release exceeding the basal release, in response to electrical and chemical stimulation, was similar in young and old rats. However, in the adult rats it was significantly lower than in both the young and old following chemical stimulation. A significantly larger number of old and adult NHs exhibited a more delayed response to chemical, but not to electrical stimulation, than did the young NHs. These data demonstrate an age-related decrease in VP release in Fisher 344 rats. Since the traumatic and basal VP release in the adult rats is similar to the release in the young rats, while the stimulated release in the adult rats resembles the response of the old animals, the results suggest that an impairment of stimulated VP release occurs at an earlier stage of the aging process than does an impairment of spontaneous (traumatic and basal) release.

Aging↗
PubMed1983

The effect of microwave irradiation on vasopressin in plasma and hypothalamo-neurohypophyseal system.

Radioimmunoreactive vasopressin was measured in plasma, neurohypophysis and hypothalamus of the rats after different procedures of killing: a) microwave irradiation; b) decapitation; c) decapitation following a stress induced by immobilization in a restrainer. Vasopressin content in the neurohypophysis and hypothalamus was much lower in microwave irradiated than in both decapitated and stressed decapitated rats. In addition, the data from microwave technique were inconsistent with a large scatter. Plasma vasopressin concentration was elevated in both the microwave irradiated and stressed decapitated rats, demonstrating that restraining of the animals induced an excessive stress. Microwave irradiation technique including the necessary manipulation of the animal proved to be less suitable than decapitation technique for the measurement of vasopressin. It is likely that vasopressin in the hypothalamus and neurohypophysis is relatively resistant against post-mortem proteolysis.

Animals↗
PubMed1983

The effect of aging on vasopressin system in Fisher 344 rats.

Vasopressin (VP) was measured by RIA in the plasma, neurohypophysis (NH) and hypothalamus (HT) of young (2 months), adult (12 months) and old (30 months) male Fisher 344 rats, ten of each age. Plasma VP concentration was significantly lower in old compared to adult and to young rats. VP content in the NH expressed per mg weight was similar in all three groups, while the hypothalamic VP content was decreased in the aged rats. This suggests that reduced synthesis and release and/or increased degradation of VP occurs in aged rats. These data are in an agreement with our previous results obtained with Sprague-Dawley rats indicating that these differences are not strain-related. In a pilot experiment, we further studied VP release from isolated perifused NH of young and old rats. Two glands of each age were simultaneously perifused in individual microchambers with medium TC 199 and subsequently stimulated by Locke's medium containing 56 mM K+. Both, the initial and the basal VP release from the NH of the old rats, as well as the response to high K+, were about a half that of the young rats. Thus, a decreased VP release may contribute to the findings of lower plasma VP concentration in aged rats.

Aging↗