Substance P regulates PTH secretion through the neurokinin-1 receptor

Expression of neural receptors in mouse meibomian gland

PURPOSE

To investigate gene and protein expression profiles of neural receptors found in the mouse meibomian gland. RNA and protein levels were determined for neuropeptide Y (NPY) receptor, vasoactive intestinal peptide (VIP) receptor, substance P (SP) receptor, and muscarinic cholinergic receptor (mAChR) subtypes M1-M5 in the mouse meibomian gland.

METHODS

Frozen sections of Balb/c mouse eyelids were subjected to laser capture microdissection to isolate pure samples of meibomian gland ductal and acinar cells. Real-time polymerase chain reaction, immunolabeling, and Western blot analysis for SP receptor, VIP receptor, NPY receptor, and mAChR subtypes M1-M5 were performed on meibomian gland ductal and acinar cells.

RESULTS

Expression of NPY1 receptor, VIP receptor 1, SP receptor, and all 5 mAChR subtypes was found in all meibomian gland ductal and acinar cells analyzed by real-time polymerase chain reaction. Immunolabeling and Western blot analysis confirmed the presence of NPY1 receptor, VIP receptor 1, SP receptor, and all 5 mAChR subtypes in the meibomian gland. The levels were variable with the duct showing greater levels of NPY1 receptor, SP receptor, and mAChRs 1, 2, 4, and 5 than with the gland.

CONCLUSIONS

VIP receptor 1, SP receptor, NPY1 receptor, and mAChR subtypes may be involved in the regulation of meibomian gland secretion. Laser capture microdissection in conjunction with gene expression analysis provides an excellent approach for studying meibomian gland cells about which relatively little is known at the molecular level.

Tachykinin family genes and their receptors are differentially expressed in the hypothyroid ovary and pituitary

Plasma tachykinin levels are known to be altered with sexual acyclicity and loss of reproductive function. Ovulatory dysfunction, as seen in postmenopausal women, is also often encountered in hypothyroid patients. To know the involvement of different tachykinin genes in hypothyroidism-associated reproductive disorders, we performed DD-PCR with the pituitary RNA of control and hypothyroid rats to see the differentially expressed gene profile. Subsequently, we selected a few clones, tachykinin being one of them. Since its expression was up regulated in hypothyroidism as it does in the sexually acyclic females, we wanted to correlate these two phenomena with hypothyroidism associated reproductive disorders. We observed differential expression of tac2 along with other tk genes and their receptors in rat pituitary and ovary, which suggests that hypothyroidism affects the expression of these genes in these tissues. The experiments were repeated in ovarian tissue obtained at surgery from hypothyroid human patients, which showed similar expression pattern of TAC3 (equivalent to rat tac2) and their receptors as in rat ovary. Significant reduction of tac2 expression in reproductively less active rat ovary suggests the association of tac2 with reproductive senescence. Our results suggest that decline in reproductive function in hypothyroidism is associated with altered expression level of tac2 and its receptors. Further investigation in this area could elucidate the possible mechanism of tachykinins' involvement in loss of sexual cyclicity and other reproductive disorders associated with hypothyroidism.

Intrastriatal dopamine D1 receptor agonist-mediated motor behavior is reduced by local neurokinin 1 receptor antagonism

Recent evidence suggests that striatal neurokinin receptors modulate dopamine (DA)-induced motor behaviors. To further examine this, we studied the effects of intrastriatal neurokinin 1 receptor (NK1R) antagonism on motor behaviors induced by direct infusion of the full DA D1 receptor agonist SKF 82958. Adult male Sprague-Dawley rats received bilateral intrastriatal 0.8-mul infusions of the NK1R receptor antagonist LY 306,740 (0, 27, or 54 nmol/side) followed by intrastriatal infusions of SKF 82958 (0 or 24 nmol/side) into the dorsal striatum. Following each infusion, rats were placed into automated activity monitors for the quantification of horizontal activity, total distance traveled, movement bouts, and stereotypy counts. As expected, SKF 82958 increased motor activity on all behavioral measures. More importantly, whereas 27 nmol was without effect, prior infusion of 54 nmol LY 306,740 significantly reduced most aspects of behavior. The results of this study suggest that functional NK1Rs within the striatum play a permissive role in the motor behaviors induced by D1R stimulation.