Unusual Reproductive Pattern of Mole rats

C.Vamsee Krishna01st Feb, 2008

Eusocial behaviour

1. Reproductive division of labour 2. Caring of young ones 3. Overlapping generations

- Non-chordates: Arthropods- Honey bees- Ants

- Queen - Drones - Workers

Hierarchy of the colony

- 8-10 cm long; 30-35 g - Poor eyesight - No fur - Sensory whiskers - No sexual dimorphism- >20 years life span- 65- 300 per colony

Naked mole rats- Heterocephalus glaber

- Kenya, Ethiopia and Somalia

- Savannah - grasslands

- Reproductive suppression-Aggressive, dominant queen- Hormonal suppression

- High O2 affinity- Sustain drought- Cold blooded- No substance P- Homocoprophage

Phenotypic plasticity in female naked mole-rats after removal from reproductive suppression

L4 was used as the representative vertebra as it provides a reliable index of vertebral lengthening independent of changes in the size of intervertebral spaces

- 12-18 month old rats are considered- 3 animals per cohort (originated from same litter

J Exp. Biol (2007), 210,4351-58

ZA = Zygomatic arch

Fig.·6. (A) Measurements of total lumbar length over the course of the 50-week study. Means (± s.e.m.) for each of the 5-week blocks of the study are plotted on the x-axis. Baseline corresponds to the 5-weekperiod prior to colony separation; the dotted line indicates the time of colony separation, and the remaining data blocks correspond to 1- 45·weeks after removal from reproductive suppression. Significantdifferences between the paired females (N=2) and males (N=2) or controls (N=2) are noted with an asterisk (P<0.05). (B) Percent mean gain in total lumbar spine length over the course of the 50-week study.Inset numbers on bars indicate the exact percent gained in lumbar spine from baseline to 45·weeks after colony separation for each of the experimental conditions. Data from cohorts CC1 and CC2 are included.

Baseline corresponds to the 5-week period prior to colony separation; the dotted line indicates the time of colony separation, and the remaining data blocks correspond to 1–45·weeks after removal from reproductive suppression. Significant differences between the paired females and males or controls are noted with an asterisk.

Social control of brain morphology

Bed nucleus of strai terminalis (BSTp) Paraventricular nucleus of hypothalamus (PVN)Medial nucleus of amygdela (MeA) Ventromedial nucleus of hypothalamus (VMH)Suprachaismatic nucleus (SCN) Anterior cortical amygdaloid nucleus (ACo)

PNAS (2007), 104, 10548-10552

-Low circulating GnRH-Quiescent hpg axis

-Low LH in males- Low serum testosterone levels

- Social stress reduce fertility in mammals

- Chronic pain – Substance P

Studies in context to humans