Detection of the N-Methyl-D-Aspartate Receptor Subunit-1 (NMDAR-1) in the Hypothalamus of the Sheep by Western Blot Analysis.

The excitatory amino acids (EAAs), L-glutamate and aspartate, are considered the major endogenous neuroactive substances involved in excitatory neurotransmission. The N-methyl-D- aspartate receptor (NMDAR) is one of the main excitatory amino acid receptors. Exogenous activation of the NMDAR results in the release of gonadotrophin-releasing hormone (GnRH) from the hypothalamus and subsequent release of luteinizing hor- mone (LH) from the anterior pituitary. The present study had two aims: to standardize the optimal amount of total protein required to identify the NMDAR subtype-1 (NMDAR-1) in the hypothala- mus of the sheep; to determine whether a difference exists in the distribution of NMDAR-1 in different hypothalamic regions (dorsal-rostral, ventral-rostral, dorsal-caudal, and ventral-caudal quadrant) in male sheep. The optimal amount of total hypotha- lamic protein required to visualize the NMDAR-1 was 100 µg. There was an effect of quadrant on the expression of NMDAR-1 in the hypothalamus of the intact male sheep. In particular, dorsal-rostral quadrant (31.5567 optical density ± 13.0831) ex- pressed more receptor than ventral-caudal quadrant (17.1517 optical density ± 13.0831; P<0.05) and ventral-rostral quadrant (16.4683 optical density ± 13.0831; P<0.05). These data sug- gest that NMDAR is more expressed in the rostral area of the hypothalamus, where the cell bodies and axons of the GnRH neurons are localized. Thus, these data allow suggest that glu- tamatergic pathway potentially is involved in modulating the re- productive activity in the ovine.