Hypertension and pregnancy are accompanied by an increase in sympathetic nerve activity (SNA) to regions of the cardiovascular system. The paraventricular nucleus of the hypothalamus (PVN) has previously been shown to be a critical centre for control of the sympathetic nervous system and there is evidence to suggest the PVN plays a role in the sympathoexcitation noted in these states1. Evidence indicates there is an increased glutamatergic influence within the PVN of heart failure (HF) and hypertensive animals1,2. Within the PVN of rats in HF, there is an increased expression of the NR1 subunit of the NMDA receptor that is correlated with sympathoexcitation1. Studies in pregnant animals are yet to confirm whether NMDA plays a role in sympathoexcitation. We hypothesise the sympathoexcitation observed in hypertension and pregnancy is a result of an alteration in NMDA receptor subunit expression that may confer a functional consequence. All experiments were performed in accordance with the Animals (Scientific Procedures) Act, 1986. A total of 12 animals were used in these studies (4 female Wistar (200g), 4 pregnant Wistar (E19) and 4 female SHR (14 weeks)). Animals were humanely killed with sodium pentobarbital (60mg/kg). The brains were removed and frozen in iso-pentane and stored at -80°C. The PVN was located3 and bilateral punches were taken. Tissue was dissolved in sample buffer and frozen at -20°C. Quantitative immunoblotting was performed using SDS-PAGE (10% acrylamide gel). Immunoblots were probed with 1μg/ml of either rabbit anti-NR1 or rabbit anti-NR2A (2 days, 4°C) followed by incubation with anti-rabbit IgG and then normalised against β-actin4. Results were quantified based on their optical densitometry using imageJ. We have confirmed the presence of the NR1, NR2A, NR2B and NR2C/D subunits within the PVN of normotensive, hypertensive and pregnant rats. For the SHR and pregnant animals, there was no change in expression levels for the NR1 and NR2A receptor subunit compared with the normotensive controls. This is the first demonstration that expression levels of the NR1 and NR2A subunits are not altered in the SHR or pregnant animal. This data suggests these NMDA receptor subunits may not contribute to the increased SNA observed in pregnancy and hypertension. In relation to NR1 subunit expression, this data differs from that reported in the PVN of heart failure animals1. However it is the NR2 subunits which confer receptor functionality. Further investigation is required to determine the significance of these findings with respect to receptor function and sympathetic over activity.