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Effects of neonatal thyroidectomy on the development of the vomeronasal organ in the rat
206
Developmental Br, in Re.vearch. 5 {19~;2~ 2()1", :Zq}:-:
Flsevier Biornedica! PI'~'~,
Effects of neonatal thyroidectomy on the development of the vomeronasal organ in the rat S. SEGOVIA, M. C. R. DEL CERRO and A. GUILLAMON* LaboratoHo de Psicobiologia, Departamento de Morfologia, Facultad de Medicina, Universidad Autonoma de Madrid, Madrid-34 ( Spaht )
(Accepted June 29th, 1982) Key words: vomeronasal organ - - hypothyroidism
The effects of postnatal thyroidectomy (on day 8 after birth) and 13tI treatment (on day 10) on the development of the vomeronasal organ (VO) has been studied in the rat. Thyroidectomized rats showed decrements in the overall VO volume, volume of the neurosensorial epithelium, neuronal population and nuclear size of neurons. These results in VO paralleled those reported in the central nervous system after thyroideetomy. It is well known that neonatal hypothyroidism induces morphological, physiological and biochemical alterations in the central nervous system (CNS)a,6, s, tl. Furthermore, behavioral deficits have also been described in the cretinous rat 4. At a morphological level it was shown that a perinatal deficiency in thyroid hormones induced decrements in neuronal size 9, t5 and volumetric development of the CNS 13,14,16, retarded myelinization of the brain and decreased rate of cell acquisitionS, is. However, to our knowledge, no attention has been paid to the possible effects of neonatal thyroidectomy on sensory receptor organs. In the present work, these effects were studied in the vomeronasal organ (VO) or Jacobson's organL The VO is an olfactory receptor organ implicated in sexual and maternal behaviors 1°,17 in whose development other hormonal systems (i.e. gonadal hormones) participate (S. Segovia and A. Guillam6n, submitted for publication). Three pregnant female Wistar rats were purchased from ICAL(Daganzo, Spain). Maleoffspring (n ~ 4) were thyroidectomized when 8 days old 7 and on day 10 they were injected intraperitoneally (i.p.) with 100 #Ci of 131 [ dissolved in 2 ml of saline. Control animals (n = 4) were sham-operated and injected i.p. with a similar volume of saline. In order * To whom reprint requests should be addressed 0165-3806/0000-0000/$02.75 © 1982 Elsevier Biomedical Press
to monitor the effectiveness of thyroidectomy and 13t 1 treatment, all animals were weighed weekly. Two months later the animals were killed by decapitation and the VOs were dissected out and placed into 10% formalin for 10 days, decalcified for 3 days • in a solution containing 5o/0 formic acid, 0 0 •., formalin and 85 % distilled water, and embedded in paraffin. Sections 6 /zm thick were serially c u t through the VO and stained with cresyl-violet. By means of a Leitz microscope, camera lucida (magnification ×192.5) and planimetric techniques, according to Donfeld et al. 5 and K6nigsmark 12, the volume of VO and its neurosensorial epithelium was determined (Fig. 1). The neuronal population was calculated following standard cell counting procedures 1,1~. In each subject, 300 nuclei of the neural receptors were measured (magnification ~: 1000). The area of the ellipse was calculated according to the formula S = (~/4) ab; where a represents the greater nuclear diameter and b the vertical diameter. Unilateral measurements were performed in all these parameters and the data were submitted to parametric (nuclear size) and non-parametric (total and neurosensorial epithelium volume and neuronal population) analyses.
207
Fig. 1. A coronal section of the vomeronasal organ (magnification4 × 10) of the rat in which are seen: a, neurosensorial epithelium, b, lumen of VO, c, respiratory epithelium; d, the nuclei bands of supporting cells; e, bipolar neurons; and f, the laminae basalis.
As can be observed in Table I, neonatal thyroidectomy and lali treatment induced a dramatic decrease in all the parameters studied. These results observed in VO paralleled those found in cerebral and cerebellar cortices by other authors. It has been reported that neonatal hypothyroidism induced decrements in: (a) volume of cerebral and cerebellar cortexg,14; (b) neuronal population irt cerebellum
and olfactory bulb a,13; and (c) nuclear size in the hippocampus 15. Thus, it could be suggested that the presence or absence of thyroid hormones during the neonatal period plays an important role in the development of the VO in the rat as it does in the CNS. The fact that the development of a sensory receptor organ such as the VO depends upon the neonatal levels of thyroid hormones and gonadal steroids (S.
TABLE I Effects of neonatal thyroidectomy on the development of the vomeronasal organ (VO)
Data show mean ± S.E.M. Treatment
VO volume (mm 8)
Neurosensorial epithe- Neuronal Rum volume (mm 3) population
Nuclear size of neurons (l~m~)
Control Thyroidectomized
1.1672 ± 0.079 0.6836 ± 0.049*
0.1390 4- 0.024 0.0859 ± 0.003*
24.66 ! 0.11 18.95 ± 0.I0"*
* P < 0.05, Mann-Whitney Test. ** P < 0.001, t-test.
35112 ± 1588.65 23746 4- 2141.29"
208 Segovia an d A. G u i l l a m d n , submitted for publi-
A h o r r o s de M a d r i d and C o m i s i d n Ases~w~: ( ief~.-
cation) stresses the p a r t i c i p a t i o n o f peripheral varia-
tifica y T6cnica (M EC, Spain). T h a n k s are duc to i)r.
bles in the b e h a v i o r a l and C N S alterations seen after
C. A v e n d a f i o and
n e o n a t a l h o r m o n a l deprivation.
their criticism o f the m a n u s c r i p t and for o r g a m z i n g
Professor
R i e n o s o - S u a r c z for
research facilities, and to Miss D e b o r a h Shapiro f,)r This w o r k was s u p p o r t e d by grants f r o m C a j a de
I Abercrombie, M., Estimation of nuclear population from microtome sections, Anat. Rec., 94 (1946) 239-247. 2 Allison, A., The morphology of the olfactory system in the vertebrates, Biol. Rev., 28 (1953) 195-244. 3 Bal~izs, R., Effect of thyroid hormone and undernutrition on cell acquisition in the rat brain. In G. D. Grave (Ed.), Thyroid Hormones and Brain Development, Raven Press, New York, 1977, pp. 287-302. 4 Davenport, J. W., Gonzalez, L. M., Hennies, R. S. and Hagquist, W. W., Severity and timing of early thyroid defiency as factors in the induction of learning disorders in rats, Hormone Behav., 7 (1976) 139-157, 5 Donfeld, E. J., Slater, D. W. and Seheffe, N., A method for accurate determination of volume and cell numbers in small organs, Anat. Ree., 82 (1942) 255-259. 6 Eayrs, J. T., Influence of the thyroid on the control nervous system, Brit. med. Bull., 16 (1960) 122-127. 7 Eayrs, J. T., Age as a factor determining the severity and reversibility of the effects of thyroid deprivation in the rat, J. Endoerinol., 22 (1961) 409-419. 8 Eayrs, J.T., Developmental relationships between brain and thyroid. In R. P. Michael (Ed.), Endocrinology and Human Behaviour, Oxford University Press, London, 1968, pp. 239-255. 9 Eayrs, J. T. and Taylor, S. N., The effect of thyroid deficiency induced by methylthiouracil on the maturation of the central nervous system, J. Anat., 85 (1951) 350-358. 10 Fleming, A., Vaccarino, F., Tambosso, L. and Chee, Ph., Vomeronasal and olfactory systems modulation of maternal behavior in the rat, Science, 203 (1979) 372-374 11 Ford, D. H. and Cramer, E. B., Developing nervous
her editorial help.
12
13
14
15
16
17
18
system in relation to thyroid hormones. In G. D. Grave (Ed.), Thyroid Hormones and Brain Development, Raven Press, New York, 1977, pp. 1-18. K6nigsmark, B. W., Methods for the counting of neurons. In W. J. M. Nauta and S. O. E. Ebesson (Eds.), Contemporary Research in Neuroanatono,, Springer, New York, 1970, pp. 315-340. Lauder, J. M., Effects of thyroid state on developmewJtof rat cerebellar cortex. In G. D. Grave (Ed.), Thyroid Hormones and Brain Development, Raven Press, New York, 1977, pp. 235-254. Lauder, J. M., Altman, J. and Krebs, H., Some mechanisms of cerebellar foliation: effects of early hypo- and hyperthyroidism, Brain Res., 76 (1974) 33-40. Moskovin, G. N. and Marshak, T. L., Thyroid hormones in CNS development: effect of hypo- and hyperthyroidism on early postnatal maturation of the rat hippocampus. In G. D6rner and M. Kawakami (Eds.), Hormones and Brain Development, Elsevier/North-Holland Biomedical Press, Amsterdam, 1978, pp. 235--240. Nicholson, J. L. and Altman, J., Synaptogenesis in rat cerebellum: effects of early hypo- and hyperthyroidism, Science, 176 (1972) 530-532. Powers, J. B. and Winans, S. S., Vomeronasal organ: cr;tical role in mediating sexual behaviors of male hamster, Science, 187 (1975) 961 963. Rosman, N. P. and Malone, M. J., Brain myelinization in experimental hypothyroidism: morphological and biochemical observations. In G. D. Graves (Ed.), 770'roid Hormones and Brain Development, Raven Press, New York, 1977, pp. 169 198.
Developmental Br, in Re.vearch. 5 {19~;2~ 2()1", :Zq}:-:
Flsevier Biornedica! PI'~'~,
Effects of neonatal thyroidectomy on the development of the vomeronasal organ in the rat S. SEGOVIA, M. C. R. DEL CERRO and A. GUILLAMON* LaboratoHo de Psicobiologia, Departamento de Morfologia, Facultad de Medicina, Universidad Autonoma de Madrid, Madrid-34 ( Spaht )
(Accepted June 29th, 1982) Key words: vomeronasal organ - - hypothyroidism
The effects of postnatal thyroidectomy (on day 8 after birth) and 13tI treatment (on day 10) on the development of the vomeronasal organ (VO) has been studied in the rat. Thyroidectomized rats showed decrements in the overall VO volume, volume of the neurosensorial epithelium, neuronal population and nuclear size of neurons. These results in VO paralleled those reported in the central nervous system after thyroideetomy. It is well known that neonatal hypothyroidism induces morphological, physiological and biochemical alterations in the central nervous system (CNS)a,6, s, tl. Furthermore, behavioral deficits have also been described in the cretinous rat 4. At a morphological level it was shown that a perinatal deficiency in thyroid hormones induced decrements in neuronal size 9, t5 and volumetric development of the CNS 13,14,16, retarded myelinization of the brain and decreased rate of cell acquisitionS, is. However, to our knowledge, no attention has been paid to the possible effects of neonatal thyroidectomy on sensory receptor organs. In the present work, these effects were studied in the vomeronasal organ (VO) or Jacobson's organL The VO is an olfactory receptor organ implicated in sexual and maternal behaviors 1°,17 in whose development other hormonal systems (i.e. gonadal hormones) participate (S. Segovia and A. Guillam6n, submitted for publication). Three pregnant female Wistar rats were purchased from ICAL(Daganzo, Spain). Maleoffspring (n ~ 4) were thyroidectomized when 8 days old 7 and on day 10 they were injected intraperitoneally (i.p.) with 100 #Ci of 131 [ dissolved in 2 ml of saline. Control animals (n = 4) were sham-operated and injected i.p. with a similar volume of saline. In order * To whom reprint requests should be addressed 0165-3806/0000-0000/$02.75 © 1982 Elsevier Biomedical Press
to monitor the effectiveness of thyroidectomy and 13t 1 treatment, all animals were weighed weekly. Two months later the animals were killed by decapitation and the VOs were dissected out and placed into 10% formalin for 10 days, decalcified for 3 days • in a solution containing 5o/0 formic acid, 0 0 •., formalin and 85 % distilled water, and embedded in paraffin. Sections 6 /zm thick were serially c u t through the VO and stained with cresyl-violet. By means of a Leitz microscope, camera lucida (magnification ×192.5) and planimetric techniques, according to Donfeld et al. 5 and K6nigsmark 12, the volume of VO and its neurosensorial epithelium was determined (Fig. 1). The neuronal population was calculated following standard cell counting procedures 1,1~. In each subject, 300 nuclei of the neural receptors were measured (magnification ~: 1000). The area of the ellipse was calculated according to the formula S = (~/4) ab; where a represents the greater nuclear diameter and b the vertical diameter. Unilateral measurements were performed in all these parameters and the data were submitted to parametric (nuclear size) and non-parametric (total and neurosensorial epithelium volume and neuronal population) analyses.
207
Fig. 1. A coronal section of the vomeronasal organ (magnification4 × 10) of the rat in which are seen: a, neurosensorial epithelium, b, lumen of VO, c, respiratory epithelium; d, the nuclei bands of supporting cells; e, bipolar neurons; and f, the laminae basalis.
As can be observed in Table I, neonatal thyroidectomy and lali treatment induced a dramatic decrease in all the parameters studied. These results observed in VO paralleled those found in cerebral and cerebellar cortices by other authors. It has been reported that neonatal hypothyroidism induced decrements in: (a) volume of cerebral and cerebellar cortexg,14; (b) neuronal population irt cerebellum
and olfactory bulb a,13; and (c) nuclear size in the hippocampus 15. Thus, it could be suggested that the presence or absence of thyroid hormones during the neonatal period plays an important role in the development of the VO in the rat as it does in the CNS. The fact that the development of a sensory receptor organ such as the VO depends upon the neonatal levels of thyroid hormones and gonadal steroids (S.
TABLE I Effects of neonatal thyroidectomy on the development of the vomeronasal organ (VO)
Data show mean ± S.E.M. Treatment
VO volume (mm 8)
Neurosensorial epithe- Neuronal Rum volume (mm 3) population
Nuclear size of neurons (l~m~)
Control Thyroidectomized
1.1672 ± 0.079 0.6836 ± 0.049*
0.1390 4- 0.024 0.0859 ± 0.003*
24.66 ! 0.11 18.95 ± 0.I0"*
* P < 0.05, Mann-Whitney Test. ** P < 0.001, t-test.
35112 ± 1588.65 23746 4- 2141.29"
208 Segovia an d A. G u i l l a m d n , submitted for publi-
A h o r r o s de M a d r i d and C o m i s i d n Ases~w~: ( ief~.-
cation) stresses the p a r t i c i p a t i o n o f peripheral varia-
tifica y T6cnica (M EC, Spain). T h a n k s are duc to i)r.
bles in the b e h a v i o r a l and C N S alterations seen after
C. A v e n d a f i o and
n e o n a t a l h o r m o n a l deprivation.
their criticism o f the m a n u s c r i p t and for o r g a m z i n g
Professor
R i e n o s o - S u a r c z for
research facilities, and to Miss D e b o r a h Shapiro f,)r This w o r k was s u p p o r t e d by grants f r o m C a j a de
I Abercrombie, M., Estimation of nuclear population from microtome sections, Anat. Rec., 94 (1946) 239-247. 2 Allison, A., The morphology of the olfactory system in the vertebrates, Biol. Rev., 28 (1953) 195-244. 3 Bal~izs, R., Effect of thyroid hormone and undernutrition on cell acquisition in the rat brain. In G. D. Grave (Ed.), Thyroid Hormones and Brain Development, Raven Press, New York, 1977, pp. 287-302. 4 Davenport, J. W., Gonzalez, L. M., Hennies, R. S. and Hagquist, W. W., Severity and timing of early thyroid defiency as factors in the induction of learning disorders in rats, Hormone Behav., 7 (1976) 139-157, 5 Donfeld, E. J., Slater, D. W. and Seheffe, N., A method for accurate determination of volume and cell numbers in small organs, Anat. Ree., 82 (1942) 255-259. 6 Eayrs, J. T., Influence of the thyroid on the control nervous system, Brit. med. Bull., 16 (1960) 122-127. 7 Eayrs, J. T., Age as a factor determining the severity and reversibility of the effects of thyroid deprivation in the rat, J. Endoerinol., 22 (1961) 409-419. 8 Eayrs, J.T., Developmental relationships between brain and thyroid. In R. P. Michael (Ed.), Endocrinology and Human Behaviour, Oxford University Press, London, 1968, pp. 239-255. 9 Eayrs, J. T. and Taylor, S. N., The effect of thyroid deficiency induced by methylthiouracil on the maturation of the central nervous system, J. Anat., 85 (1951) 350-358. 10 Fleming, A., Vaccarino, F., Tambosso, L. and Chee, Ph., Vomeronasal and olfactory systems modulation of maternal behavior in the rat, Science, 203 (1979) 372-374 11 Ford, D. H. and Cramer, E. B., Developing nervous
her editorial help.
12
13
14
15
16
17
18
system in relation to thyroid hormones. In G. D. Grave (Ed.), Thyroid Hormones and Brain Development, Raven Press, New York, 1977, pp. 1-18. K6nigsmark, B. W., Methods for the counting of neurons. In W. J. M. Nauta and S. O. E. Ebesson (Eds.), Contemporary Research in Neuroanatono,, Springer, New York, 1970, pp. 315-340. Lauder, J. M., Effects of thyroid state on developmewJtof rat cerebellar cortex. In G. D. Grave (Ed.), Thyroid Hormones and Brain Development, Raven Press, New York, 1977, pp. 235-254. Lauder, J. M., Altman, J. and Krebs, H., Some mechanisms of cerebellar foliation: effects of early hypo- and hyperthyroidism, Brain Res., 76 (1974) 33-40. Moskovin, G. N. and Marshak, T. L., Thyroid hormones in CNS development: effect of hypo- and hyperthyroidism on early postnatal maturation of the rat hippocampus. In G. D6rner and M. Kawakami (Eds.), Hormones and Brain Development, Elsevier/North-Holland Biomedical Press, Amsterdam, 1978, pp. 235--240. Nicholson, J. L. and Altman, J., Synaptogenesis in rat cerebellum: effects of early hypo- and hyperthyroidism, Science, 176 (1972) 530-532. Powers, J. B. and Winans, S. S., Vomeronasal organ: cr;tical role in mediating sexual behaviors of male hamster, Science, 187 (1975) 961 963. Rosman, N. P. and Malone, M. J., Brain myelinization in experimental hypothyroidism: morphological and biochemical observations. In G. D. Graves (Ed.), 770'roid Hormones and Brain Development, Raven Press, New York, 1977, pp. 169 198.