Inhibition of Angiotensin II receptors during pregnancy induces malformations in developing rat kidney.

Evidence suggests that Angiotensin II plays an important role in the complex process of renal organogenesis. Rat kidney organogenesis starts between E13-14 and lasts up to 2 weeks after birth. The present study demonstrates histologic modifications and changes in receptor localisation in animals born from mothers treated with Angiotensin II, Losartan or PD123319 (1.0 mg/kg/day) during late pregnancy. Angiotensin II-treated animals exhibited very well developed tubules in the renal medulla in coincidence with higher AT(1) binding. Control animals exhibited angiotensin AT(2) binding in the outer stripe of the outer medulla, while in the Angiotensin II-treated animals binding was observed to the inner stripe. In Angiotensin II-treated 1-week-old animals, the nephrogenic zone contained fewer immature structures, and more developed collecting tubules than control animals. Treatment with Losartan resulted in severe renal abnormalities. For newborn and 1-week-old animals, glomeruli exhibited altered shape and enlarged Bowman spaces, in concordance with a loss of [(125)I]Angiotensin II binding in the cortex. Blockade with PD123319 led to an enlarged nephrogenic zone with increased number of immature glomeruli, and less glomeruli in the juxtamedullary area. Autoradiography showed a considerable loss of AT(1) binding in the kidney cortex of PD123319-treated animals at both ages. The present results show for the first time histomorphological and receptor localisation alterations following treatment with low doses of Losartan and PD123319 during pregnancy. These observations confirm previous assumptions that in the developing kidney Angiotensin II exerts stimulatory effects through AT(1) receptors that might be counterbalanced by angiotensin AT(2) receptors.

Neonatal superior ovarian nerve transection disturbs the cyclic activity of the female rats.

The neural pathway most related with ovarian steroidogenesis has been identified as the superior ovarian nerve (SON). This work constitutes the first study of the effects of early ovarian SON transection, which was performed in rats of 4 days of age (SON-t rats) to magnify the effects of the denervation. The rats were studied at the prepubertal (30 days), peripubertal (41 days) and adult cyclic in dioestrus (60 days) reproductive stages. The SON-t rats showed a delay of vaginal opening, a notable disruption of oestrous cyclicity, and a large number of corpora lutea. In all the stages, the circulating levels of FSH, prolactin and growth hormone were lower in SON-t rats than in controls, whereas LH did not vary. Serum androstenedione levels were higher in SON-t rats at 30 days and lower at 41 days, compared with control animals while no difference was observed at 60 days. Serum progesterone levels did not differ between control and SON-t, but serum oestradiol concentrations were higher in SON-t rats in all of the stages. At the peripubertal stage, there were fewer ovarian beta-adrenergic receptors in SON-t ovaries, associated with a rise in the ovarian content of norepinephrine, but no changes were observed in SON-t rats at 30 and 60 days with respect to the controls. The release of progesterone in vitro from luteal cell in SON-t rats at 60 days was reduced in basal condition and under ovine LH or FSH stimulation, when compared with control animals; while no difference was observed in presence of isoproterenol or androstenedione in the culture medium. In corpora lutea of SON-t rats at 60 days, no change was observed in the activity of 3beta-hydroxysteroid dehydrogenase (3beta-HSD), but the activity of 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) was reduced, suggesting abnormal luteolysis in spite of the large number of corpora lutea. The interruption of innervation at an early age by SON transection is very important in the regulation of ovarian development in prepubertal and cyclic rats. The functional changes observed in the ovary suggest a possible alteration in the hypothalamic-hypophyseal axis.

Adrenomedullin and its receptors are expressed in the zona glomerulosa of immature and adult rat adrenals: evidences of upregulation of ADM system in immature glands.

Evidence has been provided that adrenomedullin (ADM) stimulates the proliferative activity of adult rat adrenal zona glomerulosa (ZG). However, the selective ADM receptor antagonist ADM(22-52), although being able to block ADM effect, was per se ineffective. In contrast, in the companion paper, we showed that ADM(22-52) depresses the proliferation rate of ZG in 20-day-old rats, suggesting the involvement of endogenous ADM system in adrenal maturation. Hence, we investigated by semiquantitative reverse transcription-polymerase chain reaction and radioimmune assay the expression of ADM system in adult and immature rat ZG. ProADM mRNA and ADM-immunoreactivity were both more elevated in immature- than adult-rat ZG. Plasma ADM concentration did not show significant age-related differences. ADM acts via two subtypes of ADM(22-52)-sensitive receptors: the L1 receptor (L1-R) and the calcitonin-receptor-like-receptor (CRLR), the latter behaves as selective ADM receptor only in the presence of the receptor-activity-modifying proteins (RAMPs)2 and 3. L1-R expression was enhanced in immature rat ZG, while CRLR and RAMP(2,3) expression did not display significant differences. It is concluded that the endogenous ADM system located in the ZG is upregulated in immature rats, and plays an important autocrine-paracrine role in the maintenance of the elevated growth rate during adrenal maturation.

Adrenomedullin and its receptors are expressed in the zona glomerulosa of human adrenal gland: evidence that ADM enhances proliferation and decreases apoptosis in cultured ZG cells.

Adrenomedullin (ADM) is a hypotensive peptide, that derives from the proteolytic cleavage of pro(p)ADM and acts through two subtypes of receptors, called L1-receptor (L1-R) and calcitonin receptor-like receptor (CRLR). CRLR may function as a calcitonin gene-related peptide or a selective ADM receptor depending on the expression of the subtype 1 or the subtypes 2 and 3 of a family of proteins, named receptor-activity-modifying protein (RAMPs). Reverse transcription (RT)-polymerase chain reaction (PCR) consistently allowed the detection of pADM mRNA in zona glomerulosa (ZG), but not zona fasciculata-reticularis (ZF/R) cells of eight human adrenal cortexes. Despite the rather high level of pADM mRNA, immunocytochemistry and radioimmunoassay showed that the expression of ADM as protein in the ZG was weak. However, ZG cells expressed peptidyl-glycine alpha-amidating monooxigenase, the enzyme converting immature ADM to the mature peptide, thereby suggesting their potential ability to produce active ADM. RT-PCR demonstrated the presence in ZG, but not ZF/R cells of the specific mRNAs of L1-R, CRLR and RAMPs1-3. Semiquantitative PCR showed that L1-R expression was higher than that of CRLR, while the level of expression of the three RAMPs was nearly the same. ADM (10(-8) M) inhibited both angiotensin-II (10(-9) M)- and K(+) (10(-2) M)-stimulated aldosterone secretion from cultured ZG cells, without affecting basal production. ADM (10(-8) M) also increased proliferative activity and lowered apoptotic deletion of cultured cells. All the effect of ADM were reversed by the ADM-receptor antagonist ADM(22-52). In conclusion our study provides evidence that i) human ZG cells express ADM and ADM receptors of both L1 and CRLR/PAMP2,3 subtypes; and ii) through the activation of these receptors, ADM exerts an aldosterone antisecretagogue action and a growth promoting effect on cultured ZG cells, the latter an effect which includes both stimulation of proliferation and inhibition of apoptosis. Taken together, these findings make it likely that endogenous ADM system plays a potentially important role in the paracrine/ autocrine regulation of human adrenal cortex.