A Clinical Review of the Psychiatric Sequelae of Primary Hyperparathyroidism

Despite one-quarter of patients with primary hyperparathyroidism (PHPT) experiencing psychiatric symptoms, there remains a dearth of literature regarding the diagnosis and further management of psychiatric sequelae in PHPT. We aim to review the literature pertaining to the epidemiology, disease presentation, pathophysiology, diagnostics, and therapeutics regarding psychiatric sequelae of PHPT with an emphasis on clinical pearls for practicing psychiatrists. A literature search was conducted using the US National Library of Medicine’s PubMed resource using the following keywords in various combinations: primary hyperparathyroidism, neuropsychiatric, calcium, psychosis, mania, depression, catatonia, delirium, parathyroidectomy, and psychotropic medication. We discuss in depth all aspects of the diagnosis and management of psychiatric sequela in PHPT. We have also identified epidemiological trends, discussed the most common clinical presentations, and postulated possible mechanisms for psychiatric symptoms in PHPT. Psychiatrists should maintain diagnostic suspicion for PHPT in older adult female patients presenting with new-onset psychiatric illness. Several mechanisms involving the following may explain the variety of psychiatric symptoms in PHPT: tyrosine hydroxylase, parathyroid hormone, interleukin-6, monoamine oxidase, calcium, and the sodium-potassium adenosine triphosphatase transporter. We recommend psychiatrists take a symptom-oriented approach to management. Treating a patient’s psychosis, mania, depression, catatonia, delirium, or eating disorder pathology via conventional therapeutics seems like a rational approach despite the underlying medical etiology. Only parathyroidectomy has been proven to be definitive in the complete amelioration of psychiatric symptoms.

Skin/Muscle Incision and Retraction Induces Evoked and Spontaneous Pain in Mice

Background

Surgery is a frequent cause of persistent pain. Unrelieved chronic postsurgical pain causes unnecessary patient suffering and discomfort and usually leads to psychological complications. The rat model of skin/muscle incision and retraction (SMIR) with decreased paw withdrawal thresholds developed by Flatters was usually used to investigate the underlying mechanism of chronic postsurgical pain.

Objectives

The aim of our study was to develop a new mice model of SMIR for further investigation with transgenic mice and so on and to evaluate the analgesic effects of clonidine and gabapentin on pain behavior with this new mice model.

Methods

Male C57BL/6 mice were anesthetized, and a 1.0-1.3 cm incision was made in the skin of the medial thigh approximately 3 mm medial to the saphenous vein to reveal the muscle of the thigh. The paw withdrawal threshold (PWT) to mechanical stimuli and the paw withdrawal latency to heat stimuli were measured before and after SMIR. Furthermore, the PWT to mechanical stimuli and conditioned place preference (CPP) was measured before and after the systemic injection of clonidine and gabapentin.

Results

SMIR-evoked mechanical hypersensitivity in mice began on day 1 after the procedure, prominent between days 1 and 10 after the procedure, persisted at least until day 14, and disappeared on day 18 after the procedure. However, the mice model of SMIR did not evoke significant heat hypersensitivity. Systemic injection of clonidine and gabapentin raised the PWT in the SMIR mice dose-dependently. Compared with the mice that underwent the sham operation, mice of SMIR spent a longer time in the clonidine-paired chamber than those of NS, while the gabapentin-paired chamber has no difference with that of NS in the CPP paradigm.

Conclusion

These data suggested that the mice model of SMIR demonstrated a persistent pain syndrome, including evoked pain and spontaneous pain. Clonidine and gabapentin could relieve mechanical hypersensitivity dose-dependently simultaneously. However, clonidine but not gabapentin could alleviate the spontaneous pain of SMIR in the mice model.

Voltage-gated calcium channels and disease

Voltage-gated calcium channels are a family of integral membrane calcium-selective proteins found in all excitable and many nonexcitable cells. Calcium influx affects membrane electrical properties by depolarizing cells and generally increasing excitability. Calcium entry further regulates multiple intracellular signaling pathways as well as the biochemical factors that mediate physiological functions such as neurotransmitter release and muscle contraction. Small changes in the biophysical properties or expression of calcium channels can result in pathophysiological changes leading to serious chronic disorders. In humans, mutations in calcium channel genes have been linked to a number of serious neurological, retinal, cardiac, and muscular disorders.

Drug targets in the voltage-gated calcium channel family: why some are and some are not

The L-type calcium channel antagonists have been, and continue to be, a very successful group of therapeutic agents targeted at cardiovascular disorders, notably angina and hypertension. The discovery that the voltage-gated calcium channels are a large and widely distributed family with important roles in both the peripheral and central nervous systems has initiated a major search for drugs active at other calcium channel types directed at disorders of the central nervous system, including pain, epilepsy, and stroke. These efforts have not been therapeutically successful thus far, and small molecule equivalents of the L-type blockers nifedipine, diltiazem, and verapamil directed at non-L-type channels have not been found. The underlying reasons for this are discussed together with suggestions for new directions, including fertility control, oxygen-sensitive channels, and calcium channel activators.