1. Joy Garrett Katy Lenz Aaron Wilber
Effects of Maternal Care on Spinal Cord Development and Reproductive Behavior in Male Rats
Joy Garrett
Katy Lenz
Aaron Wilber

2. Maternal Licking Behavior
During first 2 postnatal weeks
Anogenital Licking
Dams lick male pups more than female pups
Important for brain development and behavior, including stress reactivity, emotionality, learning and memory, and sexual behavior

3. Maternal licking influences adult male sex behavior
Reducing maternal licking produces deficits in male copulatory behavior:
Longer latency to ejaculation
Longer post-ejaculatory intromission latency
Longer inter-intromission intervals

4. Spinal Nucleus of the Bulbocavernosus (SNB)
Sexually dimorphic
Hormone sensitive
Controls penile reflexes during copulation
Development is activity-dependent
Dendritic development is biphasic:
outgrowth until P28
retraction from P28 until P49

5. Maternal licking alters SNB motoneuron number
Graph from Moore et al. (1992)

6. Adult dendritic length is affected by maternal licking
Control
Reduced Licking
Adult dendritic length per motoneuron is regionally reduced by
approximately 50% in the reduced licking offspring

7. Experimental Set-Up
Zinc sulfate reduces maternal licking by reducing olfactory acuity
P1, 2, 3, 5, 8, 11, 14
ZINC SULFATE
SALINE
1)HRP injection: P28 or P49
2)Hormone Assay: P1, P7, or P14
3)Immunohistochemistry: P49
4)Gene Array: P49

8. 1. Neuroanatomy
Already know adult dendritic length is affected. We will also look at an earlier developmental timepoint (P28) to see if dendritic outgrowth is affected versus dendritic retraction
Horseradish peroxidase (HRP) retrograde labeling allows visualization of SNB motorneuron morphology
Use Neurolucida to reconstruct dendritic arbor across the population of motoneurons

9. 2. Hormone Assay
Deprivation of maternal care is a stressor: causes increases in both ACTH and CORT
SNB motoneurons highly express glucocorticoid receptors (GR)
Stress also suppresses the HPG axis production of testosterone (T), and SNB motoneuron dendrites depend on T
Perform an EIA on the plasma of control and licking-deprived rat pups on days 1, 7, and 14, to look at T and CORT levels

10. 3. Immunohistochemistry
It is possible that licking-induced changes in steroid hormone receptor expression could control the effects of licking on SNB dendritic morphology.
Both GR and androgen receptors (AR) of receptors are expressed highly in the SNB
On P49, perform immunohistochemistry on control and licking-deprived rats to look for differences in GR and AR expression
Photomicrograph taken from
Blanco et al. (2003)

11. 4. Gene Array
Other molecular factors affect dendritic arborization of SNB motoneurons (e.g. ciliary neurotrophic factor (CNTF) and brain derived neurotrophic factor (BDNF)). Many of these factors are target-derived.
Perfrom a gene microarray on purified RNA of the SNB muscle tissue both during the maternal licking period and in adulthood (P49)
This will demonstrate which
genes are up- or down-
regulated by maternal care