Being tryptophan (TP) the precursor of biogenic amine and neurotransmitter serotonin (5-HT), an ontogenetic and endocrinological study has been designed on developing rats in utero of mothers Tryptophan (TP) deprived (TF) at day 1 (exp 1) and 14.5 (exp 2) after conceptus in order to verify the supposed determining role of the serotonergic system (SS) in sexual differentiation in mammals. TF-feeding has been pursued uninterruptedly in the litter after birth, during lactation and postnatal development. TF pregnant rats were obtained by withdrawal of TP sources from chow composition. In both exp 1 and 2 the litter showed at birth a significant physical underevolution, that worsened, during post-natal development, to a much more marked dwarfism in exp 1 pups. At 30 days postnatal age, whereas the female exp 1 rats showed a right-timed onset of puberty, neither descensus of the testes nor spermatogenesis could be observed in the male rats of the same experiment. Endocrinologically the males showed a significant reduction of plasma FSH levels, but also a slight increase of those of LH. Moreover: a marked hypoandrogenism and a severe hypoprolactinaemia (PRL: 0.35 +/- 0.05 and 0.35 +/- 0.06 vs. 13.05 +/- 2.18 and 13.90 +/- 2.28 ng/ml of the controls at 30 and 53 days p.n. age, respectively) characterized the males of this group. Hypoprolactinaemia was the major docrinological finding also in the female litter, which, however, at 30 days p.n. age showed the typical histological patterns of a cycling ovary, i.e. growing secondary follicles with scattered antral spaces, and thus a right-timed pubertal maturation, in spite of the significant lower plasma levels of pituitary gonadotropins and sex steroids. When mothers were tryptophan deprived at day 14,5 of pregnancy (exp 2), the litters showed a less marked dwarfism, persistent, severe hypoprolactinaemia as in exp 1 rats, but a normal right-timed onset of puberty in both male and female rats. Taken together these findings confirm on the one hand the close relationship between SS and PRL. On the other hand they suggest a major, crucial role of PRL played in the male rat before day 14,5 of intrauterine development, presumably intervening in the synthesis of LH receptors sites by the maturing Leydig cells in the male gonads.

Pre and postnatal sexual morphogenesis and maturation in truptophan deprived rats during ontogeny. Postulated control in the male by a serotonin-prolactin system

IMBESI, Rosa;
1995-01-01

Abstract

Being tryptophan (TP) the precursor of biogenic amine and neurotransmitter serotonin (5-HT), an ontogenetic and endocrinological study has been designed on developing rats in utero of mothers Tryptophan (TP) deprived (TF) at day 1 (exp 1) and 14.5 (exp 2) after conceptus in order to verify the supposed determining role of the serotonergic system (SS) in sexual differentiation in mammals. TF-feeding has been pursued uninterruptedly in the litter after birth, during lactation and postnatal development. TF pregnant rats were obtained by withdrawal of TP sources from chow composition. In both exp 1 and 2 the litter showed at birth a significant physical underevolution, that worsened, during post-natal development, to a much more marked dwarfism in exp 1 pups. At 30 days postnatal age, whereas the female exp 1 rats showed a right-timed onset of puberty, neither descensus of the testes nor spermatogenesis could be observed in the male rats of the same experiment. Endocrinologically the males showed a significant reduction of plasma FSH levels, but also a slight increase of those of LH. Moreover: a marked hypoandrogenism and a severe hypoprolactinaemia (PRL: 0.35 +/- 0.05 and 0.35 +/- 0.06 vs. 13.05 +/- 2.18 and 13.90 +/- 2.28 ng/ml of the controls at 30 and 53 days p.n. age, respectively) characterized the males of this group. Hypoprolactinaemia was the major docrinological finding also in the female litter, which, however, at 30 days p.n. age showed the typical histological patterns of a cycling ovary, i.e. growing secondary follicles with scattered antral spaces, and thus a right-timed pubertal maturation, in spite of the significant lower plasma levels of pituitary gonadotropins and sex steroids. When mothers were tryptophan deprived at day 14,5 of pregnancy (exp 2), the litters showed a less marked dwarfism, persistent, severe hypoprolactinaemia as in exp 1 rats, but a normal right-timed onset of puberty in both male and female rats. Taken together these findings confirm on the one hand the close relationship between SS and PRL. On the other hand they suggest a major, crucial role of PRL played in the male rat before day 14,5 of intrauterine development, presumably intervening in the synthesis of LH receptors sites by the maturing Leydig cells in the male gonads.
Ontogenesis; Puberty; Serotonin; Sexual differentiation
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/47400
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