Please review the following:

Developmental and cell type-specific expression of the neuronal marker NeuN in the murine cerebellum

Anja Weyer andKarl Schilling*

Journal of neuroscience research, 2003 - Wiley Online Library

Subpopulations of GABAergic neurons containing parvalbumin, calbindin D28k, and cholecystokinin in the rat hippocampus

A. I. Gulyás1,2, K. Tóth1,4, P. Dános2,3 andT. F. Freund1,2,*

Journal of Comparative …, 1991 - Wiley Online Library

Calbindin-D28k Immunoreactivity is a Marker for a Subdivision of the Sexually Dimorphic Nucleus of the Preoptic Area of the Rat: Developmental Profile and Gonadal Steroid Modulation

Sickel andMcCarthy

Journal of neuroendocrinology, 2000 - Wiley Online Library

strengths: many of the antibodies against both proteins are quite specific and good.  Weaknesses: it depends on why you are using these and what species is being examined.  For Calbindin, good rabbit polyclonals enable clean and strong staining.  However it must be recognized that these proteins only label a sub set of GABA neurons.  For mice it is quite good (see Entezam A, Biacsi R, Orrison B, Saha T, Hoffman GE, Grabczyk E, Nussbaum RL, Usdin K. Regional FMRP deficits and large repeat expansions into the full mutation range in a new Fragile X premutation mouse model. Gene. 2007 395(1-2):125-34. PMID: 17442505).  For NeuN, one must recognize two features that impact its usefulness:  1) the best antibodies are mouse monoclonals and these do not work well on mouse tissue.  Rather, chemicon's biotinylated anti-NEUN should be used and followed by a goat anti-biotin that then serves as the primary antibody.  We found one with a titer of 1:100,000 that worked well when the biotinylated anti NeuN was used at 1:10,000-20,000.  Use of just avidin and enzyme or fluorescence is going to reduce substantially the effective titer of the NeuN antibody (already low due to biotinylation). 2) it must be recognized that the Purkinje cells do not express NeuN but other cells of cerebellum do.

If you are planning on looking in areas such as the preoptic area, the examination of NeuN and calbindin can be influenced by the sex of the animal and age. Young tissue can require a different concentration of antibody if the antigen is of lower concentration than would be needed in adults. NeuN in areas such a hypothalamus is not expressed in all cell populations or is very low even in adults (magnocellular system, some of the arcuate neurons, and in the sexually differentiated regions, expression in periventricular populations is lower than other nearby populations.  One size does not fit all.

Thank you for valuable answers! I should have added the following: 

Primary antibodies: mouse anti-NeuN (1:300), and rabbit anti-Calbindin-D28k (1:1500). Incubated over night in appropriate serum. Secondary antibody was anti-mouse (1:200). ABC method with DAB for chromogenic visualization.

I'm only working with the piriform cortex (olfaction).

I would be sure to retitrate the primary antibodies (the Calbindin we have worked with at around 70,000 with ABC); the NeuN as I mentioned with 1:20,000 for the biotin anti Neun and then 1:100,000 for anti biotin (both at 48 hrs),  We have now done extensive comparisons of 24 vs 48 hr 1˚ incubation and the latter enables about 3x less primary for the same staining.  If you are not following our protocol, take a look at it and see if it gives cleaner results with less primary. Piriform cortex should be easy once you solve the mouse on mouse problem