~~Apocrine sweat glands are involved in thermoregulation via evaporative heat loss in the bovine and are most active at temperatures above thermoneutral. We have previously shown that serotonin (5-HT) receptors 5-HT 1b, 2b, 4, and 7 are found in whole skin, apocrine sweat glands, and epithelial cells, while 5-HT 2a is present in whole skin and epithelial cells. It has been shown that prolactin (PRL) plays a role in lactational homeostasis, because mammary glands are modified apocrine sweat glands, we hypothesized that PRL receptors would be present in sweat glands. Additionally, we looked at adrenergic (ADR) receptors, as epinephrine is known to influence sweating response. The present study was conducted to determine if the 5-HT, PRL, and ADR systems are involved in thermoregulation by examining the cDNA expression of receptors through conventional PCR in bovine whole skin, apocrine sweat glands, and epithelial cells. For the 5-HT system, brain was used as control and additional isoforms classified were 5-HT 1a, 1d, 1f, 5a, and 6. We identified isoforms 5-HT 1d, 1f, and 5a in whole skin, apocrine sweat glands, and epithelial cells, whereas 5-HT 1a is present in whole skin and epithelial cells, and 5-HT6 is present in whole skin and apocrine sweat glands. For the PRL system, bovine mammary epithelial cells (BMEC) were the control and 2 isoforms were identified: PRL receptor long (PRLr-L) and PRL receptor short (PRLr-S) which differ in their intracellular domain length and sequence. We found PRLr-S in whole skin, apocrine sweat glands, and epithelial cells, while PRLr-L is in whole skin only. For ADR receptors, BMEC and liver were used as control, and we found α1 ADR 1a, α2 ADR, β1 ADR, and β2 ADR receptors in whole skin, apocrine sweat glands, and epithelial cells. α1 ADR 1b was only present in BMEC and liver, while α1 ADR 1d was only in BMECs. The presence of these receptors in the apocrine glands and epithelial cells indicates that the 5-HT, PRL, and ADR systems are involved in regulation of apocrine sweat gland function.