Elsevier

Neuroscience

Volume 100, Issue 2, 14 September 2000, Pages 327-333
Neuroscience

Reduced number of neurons in the hippocampus and the cerebellum in the postnatal guinea-pig following intrauterine growth-restriction

https://doi.org/10.1016/S0306-4522(00)00271-2Get rights and content

Abstract

Intrauterine growth restriction is a risk factor for neurological and behavioural deficits in children although the precise underlying biological correlate for this is unclear. The present study shows that animals with intrauterine growth restriction, induced by a period of reduced placental blood flow during the second half of pregnancy, demonstrate reduced numbers of neurons in the hippocampus and the cerebellum in conjunction with retarded dendritic and axonal growth within these structures.

Intrauterine growth restriction was induced at 30 days gestational age by unilateral uterine artery ligation in pregnant guinea-pigs. At one week of age, the total number of CA1 pyramidal neurons in the hippocampus and the Purkinje neurons in the cerebellum were determined using the combined fractionator/optical disector technique. The Cavalieri Principle was used to determine the volume of specific regions within the hippocampus and cerebellum. The body weight of animals that were classified as intrauterine growth-restricted was reduced by 42% (n=8) compared with control animals (n=8, P<0.001), while there was a smaller effect on brain weight (16% reduction, P<0.01). Estimates of the total number of neurons showed a reduction in CA1 pyramidal neurons in growth-restricted animals (4.19±0.43×105) compared with control (5.20±0.44×105, P<0.01), and the volume of the stratum oriens layer above the CA1 region, which contains the apical dendrites of the CA1 pyramidal neurons, was reduced by 21% (P<0.01) in growth-restricted animals. In the cerebellum there was a reduction in the number of Purkinje neurons in growth-restricted animals (3.97±0.50×105) compared with control (5.13±0.52×105, P<0.01), and in the volume of the molecular layer (17%, P<0.05), the internal granular layer (22%, P<0.01) and in the volume of the cerebellar white matter (23%, P<0.01).

These results show that a period of placental insufficiency during the second half of pregnancy can effect brain development in a way which could lead to neurological and behavioural deficits in the postnatal animal.

Section snippets

Surgery

Plug-mated females were housed under standard conditions in a 12-h dark/light cycle, fed ad libitum with rabbit/guinea-pig pellets and water. Surgery was performed on 13 pregnant Dunkin–Hartley guinea-pigs from Monash University, at 28–30 days of gestation (term ∼ 68 days). Chronic placental insufficiency was induced by unilateral ligation of the maternal uterine artery as previously described.31 Briefly, the mesometrium of the right uterine horn was exposed via a midline incision and the

Neuronal counts

The optical fractionator44 was used to obtain estimates of total number of pyramidal neurons in the CA1 region of the hippocampus and Purkinje neurons in the cerebellum. This unbiased stereological method combines fractionator sampling and optical disector counting. Using this technique the number of neurons are systematically counted with the optical disector technique,17 within a known fraction of the selected brain region. For each animal, sections are selected at predetermined uniform

Development of the hippocampus and cerebellum in the fetus at 30 days gestation.

At the time of uterine artery ligation (30 days gestation) fetuses weighed 6.71±1.00 g and brain weights were 0.56±0.02 g, representing 5% and 16%, respectively of the weights at birth in the normal guinea-pig. The cerebellum appeared extremely immature and consisted predominantly of densely packed undifferentiated neurons (Fig. 1A). A band of cells, five to six cells in width, containing mitotic figures, comprized the external granular layer. A second band, three to four cells thick, was evident

Discussion

This study has demonstrated, using modern unbiased stereological techniques, that a period of reduced placental blood flow during the latter half of pregnancy can affect neuronal numbers in the hippocampus and the cerebellum in postnatal animals. Animals with growth restriction showed a reduction in the total number of CA1 pyramidal neurons in the hippocampus and in Purkinje neurons in the cerebellum. Furthermore, the volumes of specific fibre layers within these structures were reduced

Acknowledgements

The authors thank Jillian Craigie for her excellent assistance with preparation of histological sections and volume measurements in the hippocampus and Prof. John Bertram for his advice on stereology. This study was supported by the National SIDS Foundation of Australia and The Mental Health Research Institute, Melbourne.

References (47)

  • S. Rees et al.

    The structural and neurochemical development of the fetal guinea pig retina and optic nerve in experimental growth retardation

    Int. J. devl Neurosci.

    (1992)
  • S. Rees et al.

    The effects of intrauterine growth retardation on the development of the Purkinje cell dendritic tree in the cerebellar cortex of fetal sheep: a note on the ontogeny of the Purkinje cell

    Int. J. devl Neurosci.

    (1988)
  • S. Rees et al.

    The vulnerability of the fetal sheep brain to hypoxemia at mid- gestation

    Dev. Brain Res.

    (1997)
  • A. Represa et al.

    Development of the cholinergic system in control and intra-uterine growth retarded rat brain

    Devl Brain Res.

    (1989)
  • P.B. Toft et al.

    Volumetric analysis of the normal infant brain and in intrauterine growth retardation

    Early Hum. Dev.

    (1995)
  • M.J. West

    Stereological studies of the hippocampus: a comparison of the hippocampal subdivisions of diverse species including hedgehogs, laboratory rodents, wild mice and men

    Prog. Brain Res.

    (1990)
  • G.K. Vollmann-Honsdorf et al.

    Chronic psychosocial stress does not affect the number of pyramidal neurons in tree shrew hippocampus

    Neurosci Lett.

    (1997)
  • M.C. Yu et al.

    Effect of hypoxia on cerebellar development: morphologic and radioautographic studies

    Expl Neurol.

    (1980)
  • B.B. Andersen et al.

    A quantitative study of the human cerebellum with unbiased stereological techniques

    J. comp. Neurol.

    (1992)
  • K.S. Bedi

    Effects of undernutrition during early life on granule cell numbers in the rat dentate gyrus

    J. comp. Neurol.

    (1991)
  • K.S. Bedi et al.

    A fractionator study of the effects of undernutrition during early life on rat Purkinje cell numbers (with a caveat on the use of nucleoli as counting units)

    J. Anat.

    (1992)
  • J. Bernal et al.

    Thyroid hormones and brain development

    Eur. J. Endocrinol.

    (1995)
  • C. Beyer

    Estrogen and the developing mammalian brain

    Anat. Embryol.

    (1999)
  • Cited by (0)

    View full text